Sunday, November 5, 2017

Powerlifters Aren't Powerful, They're Forceful: a note on what we're measuring with velocity based training (spoiler: it's velocity)

  • This whole article is esoteric. This is probably as far in depth I'm going to get with power because it really isn't a huge factor for powerlifting
  • Even though there are strong correlations between barbell velocity and several other variables (load, intensity, exertion, your favorite skittles flavor, etc), you're not a Doctorate of all the Strong Things for using VBT. You're just another dude that collects numbers
  • There is no gold standard of velocity based training's metrics. It's still kind of up for debate, especially if you're using it for things like estimating power, force, work, and capacitive magnetic reactance. Please don't use your VBT device for capacitive magnetic reactance
  • Basically, the information we get from VBT, while potentially powerful, really isn't that large of a step forward than quantifying our understanding there's an inverse relationship between %1RM and the volume (sets X reps X weight). It's better than the traditional programming model (opinion), but not that much
  • There are known knowns. Things that we know that we know. There are known unknowns. Things that we know that we don't know. But there are also unknown unknowns. Things that we don't know that we don't know. And ultimately: the absence of evidence is not the evidence of absence prolly means we're guessing
  • I really don't follow up on the things that I plan to do, but here's a page worth of shit posting based on the things I've been reading. No more planned posts.


In the first post of this series, I did several comparisons of 3 different sensors for variations of the squat, bench press, and deadlift. In that post, my comparison measure was 2D video analysis. The obvious red flag here is that of all the comparison measures - 2D video analysis sucks. But this brings into question as to what's an appropriate criterion measure, or gold standard of comparison, when we talk about velocity based training devices. Also, what about the other metrics most units pull besides velocity? How about force, power, and work?

Having these criterion measures is important. For sake of explanation, hydrostatic weighing is the gold standard for body composition (technically it's potassium counting, but we fucked that up with the nuclear age). Bioelectrical impedance, waist-neck approximations (the "Navy equation"), DXA, and BodPod are all compared to underwater weighing typically when evaluating them for accuracy and reliability. You can compare one of these methods to another besides hydrostatic weighing (IE: the navy equation vs bod pod), but the comparison always relates back to the criterion measure - underwater weighing. A good criterion measure will be highly accurate and reliable. Accurate meaning it measures close to the actual value and reliable meaning it will reproduce that value with relatively low variance.

Think of it like three weather men. One is always 10 degrees warmer than he forecasts, but it's consistent. The other one is usually within 5 degrees of the actual temperature, but could be lower or higher. The last one is always 5 degrees above. While he's as accuracte as the 2nd weatherman, he's also more consistant. Actually this is a horrible analogy. No one gets their weather forecast from the nightly news anymore. Moving along
It's a common remark that all you need to know about lifting you can learn in a physics textbook. Yet the same people that say these sorts of things have "power" days in their routine that aren't necessarily powerful or are basically flying in the face of some basic mechanics. Volume is a shorthand metric we use, as is intensity. The underlying variable for volume is work, and intensity is force relative to a maximum. These things aren't necessarily intuitive though, so we shorthand volume with the number of reps by weight, distance, laps, whatever.  Likewise, peak force isn't easily quantifiable, so we just use a ratio relative to our 1 repetition maximum. There's really nothing wrong with that until you start implying that variable resistance (bands, I'm talking about bands) accelerated as fast as possible has a meaningful difference from doing a 1RM. You really wouldn't know that any more than you would you know your altitude just by feel. It might sounds like I'm taking shots at the usual suspects, but really every coach needs to make some assumptions about mechanics as they relate to training because measuring all these things aren't meaningful. And ultimately, the body's response to training isn't exactly required to make sense. Sometimes it just works, albeit sometimes in spite of and not because of the training method. We need to be honest about our instruments' and methods' limitations. I do this all the time with VBT when I talk about deadlifts. Mean concentric velocity has less meaning with deadlifts.

So this will highlight the insufficiency of certain velocity based methods.

Video Analysis as a Criterion Measure of Velocity and Power

Video analysis is probably one of the old school reliables for velocity. Not the best, but has been the mainstay since before VHS. You can record something with a ruler in the frame and use the frame rate and distance of that scale to get a general idea of the rough edges of the movement. Folks have been doing this for sprinters, weightlifters, and all sorts of olympic sports for years. Nowadays, we've opened that up to the masses through things like Dartfish, Coach's Eye, Kinovea, and Tracker. These are all entry-level tools and very valuable.

What you lose in 2D video analysis is essentially depth. You can get horizontal and vertical distance, but getting a measurement outside of your initial measurement is sketchy. An easy way of thinking about this is weight plates. An Olympic weight plate is supposed to be 0.45 meters in diameter. So when analyzing bar speed, it's a pretty easy measure to use. Here's the information lost with 2D video though:
Ian Wilson courtesy of the Hook Grip instagram account.
Both of these plates are the same size when viewed in the same depth,
but it obviously fails when viewed in this objective
The key takeaways are to analyze objects in the same plane, film horizontally and vertically perpendicular to the plane you plan to measure, and have a known unit of measure (a ruler within frame, standardized disc sizes, etc). Some other issues come up concerning video quality and frames per second. Thirty frames per second are going to lose a lot of information from frame to frame, whereas 120 is going to capture a large amount. Likewise, better video quality is going to give you clearer edges to measure. Some phones that film in slow motion are capable of capturing 240 frames per second at a lower quality, so you have to manage clarity of the video against the number of frames you need. The right way to go about this would be to buy something that puts GoPro cameras to shame, but that's not a realistic solution for coaches living in the real world.

Now it's important to note that programs like Kinovea have been validated when it comes to simple movements, and we can describe powerlifting as simple movements. We can postulate about how the bench press is a full body movement and how all three lifts hit all of the things and yada yada. It's simple. There's an upward motion and a downward motion. That's simple. We only make it complicated by focusing on the minutia. Powerlifting is stupid simple, stupid.

A step up would be 3D motion analysis. Using an array of cameras about a stage, we can track movement in three dimensions. This helps understand more complicated movements as well as sort out the axes that affect rather simple movements. Much like with 2D video analysis, you're going to have a known unit of measure within the frame during initial calibration. This helps the software understand position, length, and movement reliably. The great advantage of 3D video analysis is you can track multiple points of interest. If you're solely interested in barbell velocity, you can place a reflective marker at different points along the barbell and body to track that. So not only can you track velocity of the barbell, but you can see the angular acceleration of each joint during phases of the movement. That angular acceleration of all the joints in the movement translates to vertical and horizontal movement by the bar.

Video analysis of this scale isn't practitioner friendly. It's cost prohibitive, technically demanding, and largely just more trouble than it's worth unless you're doing research. On the research front, Lake et al have heralded the use of a force plate and video analysis as a criterion measure to determine power. The force plate measures force and the video analysis measure velocity, so you get the all the components you need. Sort of.

Let's bring it back to barbells though, since that's the sort of thing powerlifting does. The issue with barbell based VBT is that bar speed isn't necessarily the velocity of the center of mass. There's debate on how you determine that, but this shows that divergence:

Lake et al's article gets straight to the business with the title: Barbell kinematics should not be used to estimate power output applied to the Barbell-and-body system center of mass during lower-body resistance exercise. I'll refer back to this later.

But how consequential is that? Volume isn't a true measure of work and intensity isn't a true measure of force, but they have been good enough to be usable. Especially when it comes to powerlifting, the difference between system center of mass (the barbell and body system) becomes less consequential the heavier you lift. As a male, your center of mass is near your belly button, and the more plates you stack on, the closer it will move towards the position of the bar. And that center of mass is going to change not just with load, but the position of your body. When this is consequential is when we're dealing with light loads: such as those done to develop power. It's a good thing the objective of powerlifting isn't about demonstrating the most power. You're really getting a metric of barbell power with most units and rough approximations of system (bar and body) for others.

One of my favorite past-times is meme-ing fitness industry stills from YouTube

Bar Tethers

Linear position transducers (what I keep calling tethered VBT devices), are the most common measurement of bar speed. Most device validations are in comparison to other, older LPTs. Some of the most common comparisons seem to be to Optitrak, Tendo, and T-Force. Just because it's the most common doesn't necessarily mean it's the most valid though. We're essentially comparing one device's yardstick to another's and seeing how close they are to one another and the frequency that the difference is the same. As long as we can keep comparing to that same yardstick, it doesn't matter. Ideally, you want accuracy and reliability, but short of that reliability across all your feasible working intensities is most important. So if a device sucks at measuring slow things, heavy things move slow, and you lift heavy things - don't do it.

Some proponents of VBT have heralded tethering devices as the gold standard. Anyone that says that is probably trying to sell a product or obfuscate what their device is measuring. As I demonstrated in the first article, it seems to be the case that tethered devices are more accurate and reliable for measuring velocity. It does not measure power or force though. To measure those things, you need force plates. You can calculate it with known masses (bar weight, body weight, etc), but it's essentially best for velocity. Everything else is approximation and calculation, and there is certainly some drift across different ranges.

I don't know how to say this better than the original author, so here it is:
"Other studies have indicated that methods that depend only on kinematic and kinetic results have limitations when used to determine power output (Cormie et al., 2007b; Hori et al. 2007). It seems that the linear position transducer technique overestimates power due to increased force output production derived from double differentiation of bar displacement. When this technique is applied also to the mass of the subject, standard biomechanical procedures are rejected in that force is determined without considering the acceleration produced through a movement (Dugan et al., 2004). Despite this limitation, our results indicate that monitoring bar velocity is a useful procedure to control load intensity in resistance exercises, as observed by other authors (Hori et al., 2007; McBride et al., 2011)" - Garnacho-Castaño
The Cormie et al paper from 2007 cited has an interesting experimental method shown here:

The key part here is the use of a force plate. The tethers are inverse mounted and it just does trigonometry to determine position across time. Both this method and the method demonstrated by Lake involved force plates. There's really no getting around actual measures of force. To put it another way, trying to use VBT devices to measure force or power is like using a thermometer to measure rainfall. Ok, not that bad, but sort of.

Another point worth mentioning is that the trigonometry used with two tethers is achieved all the same using GymAware's technology. Rather than measuring the lengths of the side of the triangle (with one unchanging known side length) determining the angles within, GymAware measures one side and an angle which gives you a measure of vertical and horizontal position (the other two sides of the triangle). All that shade you been throwing on social about trig, and now it's actually kinda useful ain't it? Trig is useful folks. Build a staircase.

It's important to point out that Cormie et al and Lake et al's method do stand in conflict to one another. To some extent, Lake is probably right that center of mass is the "real" variable we should be measuring (kind of like how work is the "real" variable for volume). At the same time, Lake does not sufficiently explain how they determine the center of mass. This isn't necessarily impossible either if you apply something like segmental densitometry (for example, DEXA gives limb weights). Without taking sides here (Lake vs Cormie), the important parts are 1) both of them point out the necessity of a direct measure with a force plate 2) both research groups have authors that have done a lot of research on powerlifters, so they're pretty damn rad.


Accelerometers seem to bridge this gap to some extent, when the right inputs are used. The issue is Force. Force is a product of mass and acceleration. If we return to the issue as mentioned by Garnacho-Castaño et al, inertial sensors would seem a likely solution. If I haven't hammered the point home yet, while accelerometer technology has failed to perform on some fronts, it could be the missing link we're looking for. This is especially pronounced with power movements.

I've talked before about how you could theoretically determine velocity when an accelerometer is attached to a fixed point if you know the lifter's height. It's a rough approximation and relies on relatively normal proportions of limb length according to height and the mechanics of exercises being relatively comparable across a broad population. That method would require a certain amount of machine learning or constants and manual inputs of the lifter. At a minimum, I would think height and weight would be important to determine force and power. That said, if tethered devices clearly excel at measuring bar velocity, then they're probably the right tool for the right job.

Banyard et al down at Edith Cowan Uni used the same method that Cormie et al used and took GymAware and PUSH head to head in one of the most comprehensive comparisons. Again, these comparisons are made with a dual tether and force plate system:
Notice this is only figure 3 and 8. You should see the rest of them. Some have insisted that the difference between actual power and GymAware's power is only 10 watts. I'm seeing 100 watts. Follow the link.
If your main take away from this is that PUSH is hot garbage and GymAware is overpriced because it measures what it says it does, you're missing the point. The point here is that I'm not sure why these are currently two separate products. A combined approach using both a tether and an accelerometer could still be affordable (assuming GymAware doesn't set the price), you'd likely see additive value. Force plates are almost out of the question.  In order to cover the size you'd need for a simple movement like a squat, you're talking about an upfront investment of $600 minimum.
Just do the math. If the cheapest tether device is $200, and a force plate set up would cost $600, that's like 4 red competition plates you can't buy.

I haven't been paying terribly close attention to PUSH, but it would appear they're actually serving their market pretty well. They've implemented a new system that uses some video processing in combination with the sensor to collect different metrics. Again, this really doesn't matter for our purposes because, well, barbells. If you are using the PUSH as a powerlifter, one great feature they've implemented is velocity cut off notification. That makes it decent for hypertrophy work (because lighter=faster), but maybe not a strength. The only other VBT device I can think of that has attempted to add another input (IE: video, displacement, etc) is the Form Sensor. However, Form's altimeter really only helps to improve vertical velocity as far as I know.

Approximations aren't all that bad

Some accelerometer systems are getting their estimates of power based on the combined input of load and body weight. This sort of works, but we have to recognize it is an approximation. The issue with most accelerometers in the end is that they tend to be thrown off by sudden changes in direction, jarring not related to the movement, and Germanic talismen inscribed with the correct order of runic scripture. Ignoring some of the inadequacies there, approximations aren't too bad. 

A good example of combined measurement and constant (manual input) measures is the Powerlift App. When you break it down, the app functions as a video stop watch. It takes a video that you use as a visual reference point, you input a range of motion for that movement (which hopefully you measure appropriately), and choose start+end points for the concentric part of a movement. It's actually pretty good at it and has been validated in a lab. All the app does is convert the start+end point frame count to determine time, dividing the ROM by that time to determine mean velocity. You're not going to get peak velocity.
Side note: Powerlift is unlike many devices in that it actually stores correlations of load and velocity, as well as many other useful funtions. Most device manufacturers could take some tips from Carlos. Technically some do this, but is a sort of way that can only be reference manually - far from optimal. 
Again, with combined measures and inputs, you can improve this further. For example, if you were to take the average of your ROM from all loads over 90%, you could improve reliability near 1RM distance. You could also manually input your MVT in advanced options, but for sake of fidelity it's probably better to only use ROM input from another device you trust and video an MVT rep to keep it relative. 

Why it Matters: Science, Theory, and Methods

When I say the science, I really mean more of the mechanics - the sort of rules that things obey. There is something troublesome about scientific training. Firstly there's the fact the science does sort of exist in a vacuum. The protocols employed by science are commonly used to elicit a response, to tease out a marked difference or similarity of one treatment versus another. It really doesn't matter if it's a realistic training program (let's pretend that's the only kind of sports science for this), but one that emulates enough elements of real training protocols but has a magnitude large enough to elicit a response. Basically, most of these programs don't have ecological validity - they aren't programs that would be optimal.

Training theory on the other hand (not "scientific theory") is basically the rationale which we think training follows. This is a blend of what coaches have seen in practice and lab rats have evaluated in a laboratory setting. That connection from A to B isn't always a straight line. For example, the force-velocity curve is more based on the functional characteristics of muscle fibers. It's not necessarily the same thing when we're talking about movement created by multiple muscles and about multiple joints.

Lastly, the methods are how we choose to execute our training theories, hopefully based on the practical applications of the science. Using bands is one such methodology. I've beaten that dead horse long enough though, so let's use Orange Theory Fitness. Orange Theory Fitness markets itself as a science-based weight loss program. It sort of is. If we think of work (joules) as a proxy for energy expenditure (calories), then high volumes of energy expenditure are more obtained at lower intensities. I'm basically saying pure cardio. That's not exactly the Orange Theory Fitness training program. Secondly, there's a significantly greater magnitude of difference obtained through diet. So it's not all bullshit, but science did not divine the right answer to Orange Theory fitness and there's plenty of caveats. But science sells. Even diet programs use that tactic.

Everyone fails at marrying these three elements together, including your gurus, to some degree. With velocity based training, most of that fault comes from the science. I spent this whole article highlighting disagreement. The training theory failing comes from over-expansion of concepts like the force-velocity curve (IE: the training zones). An extension of that carries over into methods. Assuming the force-velocity curve can be made so specific in gross movements could be made even worse with the idea when adding variable resistance.

Putting it All Together

If you own a tether system, stop being so uppity. You have the most appropriate system for measuring velocity, and even that is still subject to error - even more so if it doesn't measure angle of pull. You could probably rig up two single axis system to improve vertical velocity measurement and maybe even track bar position throughout a movement, but there is no consumer level solution yet. Beyond the fact that tethers aren't appropriate for movements in three planes of motion, accelerometers do have additive value to help us better measure simple training metrics - like force, power, and work. We don't have those solutions yet, but that's likely the future. It might seem ridiculous to forecast the future like that, but given the relative utility of Accelerometer-GPS units for field practice, it's not too far off.

Velocity based training is supposed to be a method to quantify things we were making guesses about. Generally, something that's powerful was subjectively fast enough and light enough. I say subjectively because it has to be someone with some authority and experience in developing powerful athletes with movements that best mediate that training quality. That sense of what is powerful is largely a presumption. As much as velocity tells us, there's still plenty we can't nail down. Operating in this unknown area is fine though. We've been operating in the unknown using simple measures for decades. But you should probably stop taking VBT measures of power and force at face value.

#MaybeJustLiftWeights #ButHaveYouReadSUPERTRAINING

Sunday, August 6, 2017

VBT: Deadlifts are not your friend

If you want a how-to-deadlift guide, I suggest my favorite website. That's not what this is.

Edit 8/8/2017 - Since I posted this two days ago, my google scholar news alert pulled up a new article examining the relationship between velocity and prediction of number of reps at a given intensity (XRM)/reps in reserve (RIR). They created generalized equations to predict XRM and RIR, but found that like all things VBT, it truly needs to be individualized. Furthermore, they showed that XRM can be determined from velocity, but RIR does not appear to be identifiable. This seems to say that it is possibly less ideal to use the exertion-velocity relationship identified by practitioners like Mladen Jovanovic than it is to use velocity to determine XRM. On a practitioner level, this seems inconsequential since you can just use the velocity-XRM relationship of that individual to drive exertion. If you want 2 RIR, just perform the velocity XRM plus 2 reps.
In effect, even though I have weakly advocated the exertion velocity-relationship, it is likely more appropriate to use the velocity-XRM relationship using your individualized data. Even though I resolved this solution specifically for the deadlift, it's actually more appropriate for more movements. I'm not going to edit this to reflect this new finding.


The deadlift is a bratty kid in velocity based training. It thinks it's the center of the universe and doesn't play by anyone's rules. If you sort through many of the velocity based training research articles, you will find an overwhelming amount of information on the bench press, bench throws, squat, jumps, squat jumps, pull ups, and prone rows. Likewise, many of the principles established in the one exercise you can often apply to the other. But you don't see much for deadlifts. One possible explanation for this is it's hard to publish negative results.

Key Points:

  • Most exercises in PL have you start at a velocity and slowly bleed that velocity off with each rep. Deadlifts do not do that though.
  • Since velocity loss is a factor in auto-regulation in VBT, there has to be a reason why.
  • Nope. Not a reason I see. Maybe deadlifts just suck?
  • I have an idea of how to solve this by re-working something else Mike T does. I steal from Mike all the time

Velocity Loss Across a Set

If you take a set for the bench press and go until failure, you will see velocity start off fast and slowly drop off to grindtown. You see the same thing with the squat. This has been termed velocity loss and is talked about to at length here.

Mean concentric velocity across multiple intensities of the bench press and half squat from Izquierdo et al.

In a previous article about the future directions in VBT, I alluded to the potential for research in different variations of movements. The research has ventured here in terms of the load-velocity relationship and appears to be continuing that way. For sake of simplicity though, here's how that has looked in the past year of my experience:

A comparison of velocity loss across multiple movement types
You see the general decrease in velocity with successive reps. It appears the deadlift doesn't do that though. You have high coefficients of determination (R2) for everything except the deadlift. Moreover, if you look at the trend line for the deadlift, it's relatively flat. It's like a table that has that one leg that needs a shim. And much like that table, I also get the impression that fixing it isn't on anyone's to-do list and we'll just continue to live with it.

Velocity Across Intensities

Deadlifts aren't entirely useless in VBT. It appears velocity is useful across different intensities, but confusing across a set. Here's an example:

Velocity across different sets in the conventional deadlift. After each set, load is increased. This plotted using only the initial velocity rather than the average of multiple reps  (3 for light, 2 for moderate, and 1 for hard sets) as I have advocated in the past.
As you can see, with each successive increase in load, velocity appears to decline. The coefficient of determination seems high enough (above 0.90 would be optimal). If you were to isolate this into the %1RM that you're most likely to work with in powerlifting (for strength or hypertrophy), most sets will fall between sets four to seven.

So while we can't regulate volume within a set (and therefore exertion), we can obvious regulate load. Likewise, you could be specific about how you regulate fatigue. An example of this would be hitting 80% 1RM for as many sets as possible. Once initial velocity drops below a predetermined velocity threshold, the volume (in sets) has been achieved.

Determining Confounding Factors

There are maybe a few things that could contribute to this phenomenon, and I'm not sure what it is. I tried to identify as many potential candidates as possible and figure out a way to tease out the results.

Sumo vs. Conventional

If you pull your deadlifts sumo: 1) you eat ass 2) you're a goddamn cheater 3) you make that singlet look good. 

For sake of argument, there's nothing that makes this phenomenon unique to deadlift type. The first graph of velocity loss across sets is sumo. The second graph was sets of 3, and in each set you get a rather noisy picture in nearly every set. So that's not it. 

From a motor learning perspective, it makes more sense for me to limit this to the sumo deadlift. It's my competition deadlift. Over the past year, I've done half a dozen different variations of the sumo deadlift. In that same time period, I've only done one type of conventional deadlift. If I was regularly cycling in conventional deadlift variants, it would make sense to prefer this. In the end, the two lifts are more similar than dissimilar. Even if you don't agree with that, take your first world problems and GTFO.

Concentric Only Lift

The common thread that squat and bench share that make them differ from the deadlift is that the lifts are preceded by an eccentric movement. The running idea here is that this eccentric loading transfers some force through the stretch reflex. Even with a pause, the stretch reflex lingers for some time. This was what prompted Louis Simmons to use the box squat and unload the muscle.

There's also the argument that velocity loss across a set could be different with touch and go vs pull and reset. I wasn't seeing such a pronounced difference on a cursory survey. Also, the rationale doesn't make sense to me since I generally see concentric-only lifts (pin presses and pin squats) to be more reliable. To tease this out, I attempted to emphasize the concentric part and start the set with the eccentric portion of the movement. I basically did what all the pull-and-reset Nazis complain about and made it into something they would hate even more. I started the bar an inch below lock on an adjustable height monolift. Then I pulled the bar that final inch as the monolift swung away. At this point, I'm able to start the deadlift by lowering it. 
The natural question is "how do you finish the set?" There's two ways. You can get to lock out and try to duck walk the weight back to the monolift like an idiot or finish by putting the bar back down on the ground. I'd like to tell you I didn't learn which method the hard way. But I did. Yes. I did. I don't think this movement helps develop anything particularly better than normal deadlifts, but if you're going to do them then just end with the bar on the floor.
This emphasizes the eccentric part across the whole set - not just from the second rep and onward. Let's just call it the "sumo droplift." You heard it here first folks.

Proudly presented by Zero Sum Gains

Range of Motion and Bar Deceleration

Powerlifting often comes down to the weak range of motion. In the deadlift, that either happens off the floor or at the knees. Typically conventional deadlifts fail due to deceleration near the knees and sumo deadlifts fail to generate enough acceleration off the floor to power the move into lockout. It could be possible that acceleration from the floor to the knees or from the knees to the lockout is the confounding factor. When that irregular behavior gets mixed in with the rest of the movement, that might be what's causing the rather noisy picture of velocity across the set.

The easy way to tease this out is by separating the parts of the movement. Block pulls are a common supporting movement. I'm just going to do them as sumo block pulls, which is less common. To get the range of motion from the floor to the knees, I've decided to use spotter arms upside down. Once both sides contact the safeties, I lower the weight again. 

If the range of motion is the issue, then obviously one of these two should come out significantly cleaner than the other.

Jefferson Deadlifts

Obviously, this will show us everything we need to know about deadlifts. This is really the only deadlift you ever need. Not even in powerlifting. This is the only deadlift you need in life.

SMDH - What it looks like

Normal sumo deadlifts are flat. This particular set has a lower coefficient of determination than the one I showed in a previous graph (0.003 vs 0.3). The sumo droplift is not only flat but has the worst coefficient of determination (R2) out of all of the lifts (translation: no. Dumpster fire). Block pulls have a downward trend and half sumo to the knees have a counterposed upward trend. Just by the look of the trend lines, it would seem like half sumo to the knees are what contributes to the noise with velocity gain across a set. In reality, though, coefficients of determination (R2) of 0.03 and 0.11 are hot garbage.

I'm not sorry you read through all that bullshit just to arrive at the fact that I don't know why deadlifts for reps doesn't work. Maybe God just doesn't want you doing high rep deadlifts. High reps=cardio, right? All I can tell you is that the things I identified as potential confounders don't appear to be it. 

So why bother? Why waste your time? Everyone seems to have this idea that because VBT doesn't work because of a lack of understanding of how to use it. It's still very useful to regulate load/intensity with velocity. Don't let frustration with VBT deadlifts drive you away from VBT.

The Work-Arounds

I've harped on the idea that VBT is only one way to autoregulate training for powerlifting. If you want to blend your methods, that's something you can easily do. If you're experienced with subjective measures like RPE, you can easily integrate that. Alternatively, you could just program your deadlifts via percent of training max. You can even augment that training max at whatever frequency you want with AMRAP sets using the usual calculation Jim Wendler uses or this. Wendler's favorite:

wt. x reps x .0333 + wt.= 1RM

There is an alternative though. Let's take for example the RPE chart from Reactive Training Systems:
Not original content. See source link
We know that the load-velocity relationship works. In that same instance, the %RM-velocity relationship works. The only issue we have is obtaining the MVT. MVT is usually the last rep in the tank whether it is a 1RM or a multiple rep max. In this case, though, MVT is best obtained through testing 1RM and can be updated on occasion with reps slower than MVT that occur in training (because that happens). With that said, we can use the %RM-Velocity slope and intercept (nerd shit, go back to the "How the Sausage Gets Made" article and download the excel files) to do a reverse look up on the velocities. 

So rather than getting %RM value to use, you can use a mock up of this chart to determine what your initial velocity should be. Here's a visual:

Assuming this works, you can better control exertion/proximity to failure. Unlike bench and squat, you can't auto-regulate within a set, using a stop velocity to tell you when to terminate a set. Instead, you're working on delayed feedback. Intensity/load is still real time, but you're basically flying blind and assuming work capacity is fairly stable. If you give up the gas mid set and hit a wall, obviously the only thing determining the end of the set is subjective feedback (IE: feels heavy, bro. I be done). 

This is the streamlined way I've done this. After playing around with how to auto-regulate deadlifts, I've taken to using MyStrengthBook's personal record table screenshot below:

The menu gives you a table of your rep-maxes, which I initially used for programming. Upon realizing I could convert the raw weights into percent 1RM, it became obvious that there is a non-real time alternative to terminate sets to a predetermined exertion level using velocity. I'm not going to say it's perfect since I'm still evaluating it, but it's food for thought.

Continuing Forward

It's been a good three months since my last update. I said from the beginning that this wasn't going to be an indefinite series. Potentials on the horizon: Gym Aware included in the comparisons, Open Barbell V3 included in the comparisons, PUSH evaluated on update sumo deadlift algorithm, an RPE-VBT excel template, and VBT/RIR in typical bro exercises (depending on lit review).

Some of the things I said in the past year have been elucidated by newer research. Not anything refuting things I said (at least none I'll admit to), but I think about half of my future directions have already been knocked off the list if not currently in-process. I'm not going to re-write that. Likewise, some issues on the manufacturer side have been changed. I try to add footnotes at the beginning where appropriate, but for the most part it's hard to keep track since I primarily train with one device.

Wednesday, May 24, 2017

A Powerlifter's Guide to VBT Pt 7: RPE to VBT translator

This entry was meant to be posted quite a bit earlier, but I delayed it. In my part of rural Texas, internet service providers crash with tiny weather upset. I was not about to type this shit out on mobile just to get it done in time.


-RPE and VBT are not competing systems.

-Which system you prefer is entirely dependent on many variables. The most important one is what type of feedback you find valuable: internal subjective feedback or external objective feedback.

-The science shows strong correlations for both, but there's some issue with the noise associated with velocity.

-The exertion-velocity relationship can explain the RPE rating system in velocity measurements, helping bridge the two worlds. Or if you're lazy, and accuracy be damned, there's an equation to level the two.

-Even if you don't care much for bridging the gap between RPE and VBT, doing the exertion-velocity relationship can open a world of programming and planning strategies. 

-Why VBT=awesome-sauce and RPE=face palm. We are competing, VBT is winning, and RPE can suck it.


Most people that tend to be into Velocity Based Training (VBT) are also actively using/interested in Rating of Perceived Exertion (RPE). RPE was popularized by Mike Tuchscherer from Reactive Training Systems. Others have outlined the advantages of RPE vs VBT vs other autoregulation systems better than I have, so I'm not going to attempt to do that. Despite how some tend to put it, VBT and RPE are not mutually exclusive practices, can exist in both harmony and in conflict to one another, and each has key takeaways to aid the other. There are caveats to using both systems.

If anyone thinks VBT is innately juxtaposed against RPE, I steal most of my new ideas from RPE and try to find a way to make them work in VBT. In fact, very, very few of the ideas I've expressed so far are original. I cite most of the ideas I'm stealing. So far, it seems like few are attempting to bridge RPE and VBT. Many tend to favor one method and use the other as a footnote barometer. I tend to favor using them on an "it depends" basis. 


Looking back at my previous writing, I have seriously taken for granted that people understand RPE. Let's alleviate that by inadequately explaining it. RPE attempts to quantify subjective feeling. Here's the infographic:
A more thorough breakdown can be found here. That said, I haven't taken the time to compare and contrast Mike T's current RPE methods against his old ones, The Strength Athlete, or anyone else's. 

There's also Reps in Reserve, which operates more like an abbreviated RPE system with no half steps. I associate this more with Eric Helms' and Zourdos' work, but you could attribute both of these methods to APRE, Borg, or Confucius. You could even argue that Renaissance Periodization/Juggernaut uses an RPE method when saying 3/fail, 2/fail, 1/fail (1-3 reps away from failure). 
The common argument for RPE/RIR is that everyone instinctually uses RPE without realizing it. Everyone uses how they feel to autoregulate their training. This can involving decreasing load when they're having an "off day" or other methods of adjusting training according to perception of readiness. While they're not wrong, that's also like saying just because I pay Social Security that I'm pretty much a Communist. That argument functions as a pidgeon-holing effort that I disagree with. I see the purpose of the argument though. 
I could equally argue that since RPE proponents consider perceived and sometimes measured bar speed, they are closet VBT fetishists. I'm not claiming that.
If I were to inappropriately simplify RPE, it's something like this: say a lifter completes an 8 rep max for 6 reps, they just did 6 @8 RPE or 6 with 2 RIR (reps in reserve). I will switch between all three of those interchangeably because I'm pretty bad at self-editing. 


Obviously, VBT is king. VBT is the absolute king of ding-a-lings. No question. It's science.

Not really, but it depends. Let's start conceptually or by "attitude." If you've been using RPE for an extended period of time, then obviously RPE is better for you, at least short term. The opposite is probably true for VBT. You could argue that VBT relies on reference velocities often in the form of tables, but you could also argue that RPE relies on tables. Both of them rely on previous experience. If you introduce a novel movement someone isn't familiar with, their referent minimum velocity threshold (velocity of last rep in the tank) or RPE rating might be meaningless. 

VBT is external and objective. RPE/RIR are internal and subjective. They're not really opposites since they both serve the same function, but in terms of how the feedback is garnered, they are opposites. Different people will find a meaningful use for both/either.

If you're bad at gauging internal, subjective intensity, then RPE won't work for you. It can be frustrating to get ahold of and in the moment if feels like your navigating with a broken compass. If that sounds familiar, then troubleshoot the situation or move on. Maybe something more objectively based is more appropriate. VBT and AMRAP sets become better options in that case. Each of those has drawbacks though. I'm not going to cover AMRAPs as an autoregulation method much - but GZCL and 5/3/1 are good examples of that.

So how could external, objective feedback be worse than something like RPE? This probably would serve better with illustration. Here's an as-many-reps-as-possible set (AMRAP):

The first rep looks like an honest attempt. I would argue this rep could be a good indicator of intensity - around 80-85% of that day's 1RM. The last rep is equally a good read, and would be a good indicator of minimum velocity threshold (MVT). Again, MVT has been a good indicator of the last rep in the tank, velocity at 1RM, or what we could call RPE 10. 

The issue is reps 3 to 5. Rep 3 takes a massive nose dive, rep 4 attempts to recover that velocity, but it isn't really regained until rep 5. At rep 5, it seems to take the same incremental loss in velocity it had in reps 1-2. There's a certain amount of noise to every measurement. The problem leveled against VBT is often that it is noisy, that its measurement varies too widely from rep to rep. We try to reduce this by choosing appropriate devices (as we've shown, with the device comparisons). You'll subconsciously try to do this if you rely solely on VBT. You'll start forcing yourself to perform sets in a way that data acquisition is more optimal - often in ways conducive to the training process, but possibly in ways that hinder the training process. The upside of VBT is you often have to think less to augment your training. If your measurements are noisy though, you have to put on your coaching cap more often and determine what's a real measurement and what's an artifact of performance. Sometimes you want to work out and not pretend to be a half-decent data scientist.


RPE is king of ding-a-lings. VBT=Communism. 

Not really, but with the limited research we have comparing the two, RPE comes out on top in a few respects. Firstly, velocity is not as good at predicting 1RM based on the levels of confidence. In the tables I've used, there's a point estimate as well as the upper and lower ranges of the estimate based on 95% and 90% confidence intervals. These intervals can be fairly wide, so the point estimate should be taken with a grain of salt.

VBT needs to be individualized and varies by exercise. The general guideline is that 0.30 m/s is MVT (1RM, 10RPE, 0 RIR) velocity for normies in the squat, and 0.15 m/s in the bench and deadlift. Zourdos et al found that experienced squatters hit MVT at a slower velocity than noobs (0.24 m/s vs 0.34). Similarly, Helms et al found the same trend, with squats clocking in at 0.23 m/s, bench at 0.10 m/s, and deadlift at 0.14 m/s. But when it comes down to the nitty-gritty, here's what that looks like in the grand context:

A value of 1 or -1 is a perfect relationship. 

You have to think of this in the context of their use though. It's far easier to gauge a 1RM attempt as a 10RPE than it is completing a 10RM for 7 reps and identifying it as a 7RPE. Much the same, it's easier to determine reps in reserve closer to failure with velocity as the referent measure than it is further from failure. For intermediate lifters, both systems tend to excel closer to failure. Both studies seem to demonstrate the relationships of velocity and RPE at 1RM, but the science is chugging along for loads short of 1RM and the information is still forthcoming. Additionally, there is something to be said about framing a user's understanding in the context of VBT. If you were to anchor velocity training in the same context that you anchor RPE, and furthermore allowed a good period of evaluation of both systems, you would likely see some changes in the results. Maybe even VBT comes out worse, or maybe that RPE is strongly associated with Sovereign wing nuts.

Anchoring is essentially how you "build" your personal RPE tables. With a 1RM and an AMRAP at a given percentage (let's say 85%), you can split the difference and generate a table of best-guesses of %1RM for every given prescription of number of reps and the corresponding RPE. See the link provided earlier in the article.

Much like you really have to force yourself to be honest when using RPE, you have to move with intention with VBT - or attempt to move every rep as fast as possible while maintaining technique. At this point, you could circle back to the common assertion by both parties, that either system performs well enough, requires at least intermediate experience to gain full utility, and either could be more appropriate than the other for different individuals.

Future directions for this could be studies showing whether or not one could accurately predict 1RM based on sub-RPE10 ratings for multiple reps. Likewise, the same sort of study could be used in the VBT realm, showing whether you can predict daily 1RM based on regular fluctuations in velocity at a standardized load. Chris Duffin mentions this in a YouTube round-table about VBT and his experience using OpenBarbell before a meet. Additionally, there is no science in the works to determine reps in reserve to velocity, something termed the exertion-velocity relationship.


AMRAPs are great at getting a submaximal measure of MVT. If you run a VBT-1RM estimation without a known MVT, you're guessing. There's two ways to get that: do an AMRAP or do a 1RM test. Obviously, the second option renders the estimation useless. Also, it shouldn't be surprising if your estimate is off. 

AMRAPs are also great to determine exertion. Exertion could very simply be explained as the proximity to failure. Assuming a MVT of 0.11 m/s, a rep at 0.19 m/s requires more exertion than a rep at 0.26 m/s. But can we take that seriously when we stop short of failure? Especially with how much noise can be in that measurement? Maybe.
Two AMRAPs pictured left, then the velocities averaged across according to the reps in reserve. Notice the change in R2

Here's two sets according to their reps in reserve. One was a 4RM, another was a 6RM. Because this is ordered by RIR, it was essentially performed in reverse (RIR 5 in the 1st graph was the first rep, RIR 3 in the 2nd graph was the first rep). You can see by the data points that there is some noise. According to the regression, the first AMRAP has a higher coefficient of determination at 0.89 than the second at 0.79. A perfect fit would be 1. When we average across, that coefficient of determination kicks up to 0.93. 

A recent exertion-velocity table that helps demonstrate
AMRAP utility in VBT
The above table shows an example of how we can smooth the noise inherent in VBT across a set. Bring your attention to AMRAP set 2, particularly in the middle. The last rep (0.25 m/s) is an honest attempt, and you can see that the first can be taken seriously to (0.36 m/s). The middle two make no sense. However, when we average two sets across, we can smooth that noise out. If we plot this averaged mean velocity across two AMRAPs and correlate it to RIR, we can interpolate how many reps we have left in the tank based on final velocity. The generalized midpoints between each rep become half-steps. A half-step might be noise, so maybe it's more useful to round it, but it could be interpreted as RPE.

Another graph of successive rep velocity decrements
from a published article, not quite as noisy as mine. 

I keep talking about noise. So what's the smallest worthwhile difference to figure out noise? It likely depends person to person. I would guesstimate it's something in the neighborhood of 5% of velocity, generally speaking, but I generally operate off of +/- 0.03 m/s. I came to this conclusion based off of individual experience, so don't hold it against me too seriously. It's a ballpark.
You'd be right to point out that there is some noise in RIR 1-3. The incremental drops in velocity aren't that large, and therefore are questionable. By using the regression, we can use the slope to get an optimal read on exertion. Much like RPE though, you'll have more reliable measures the closer you get to 10 RPE or 0 RIR. Much like we don't worry about anything below 6 RPE to begin with, you do see noise in velocity at 6 RPE or lower. 
If you were to run this against a regression and estimate RPE according to velocities, you sort of force a fit, but it does ball park things for you. The main issue is when you're going for large sets in excess of 10. Larger sets are going to be more noise than they are data, so I try to keep the nRM attempts under 10 reps. It's worth pointing out that half steps in RPE might be truncated due to the size of the incremental velocity losses. Guess what fills in the gaps in this case? Subjective, internal feedback. Just like you can use VBT to spotcheck RPE, you can do the opposite.
Sounds like a bunch of hand-wavy mathemagic. Possibly. If you ask me for a peer-reviewed article that supports this assertion and I can't help you. The best I do is refer you to people that are more qualified than me. To be fair, in a previous article I did mention this as an outstanding issue that researchers need to resolve. 


I've tried to do my due diligence here. A quick search through RTS's forums will find mostly inquiries about how devices compare. One reply in particular from November of 2014 has the following equation from Mike T:
This was back in 2014 though and I'm not sure if Mike has since disregarded this. I also can't verify whether or not this matches up with my experience because I haven't used it extensively.

[Edit 8/8/2017: It would appear from an article in July from IJSSP that generalized equations don't work, however this could be due to the fact they didn't account for MVT. In a follow up article, I advocate using initial velocity to determine XRM and regulating exertion using that relationship. This appears to be back by the research in that same article.

Edit 9/03/2017: According to unpublished work by Garcia-Ramos, a single repetition to gauge daily 1RM tends to overestimate. A better method is to use 2 points to generate the estimate. That's sort of what many practitioners did anyways without so much evidence and with a bit more intuition. TBH, VBT is just gonna be one of those things where the practitioners are going to be one step ahead of the science at all times.]


Reviewing what we've done so far leading up to this article... that's a load-velocity test (which is just a fancy data-geek warm up) and two AMRAPs. The load-velocity (L-V) table becomes a %1RM-velocity (%1RM-V) relationship. The two AMRAPs give you MVT, turning to L-V into a 1RM estimate. Then the two AMRAPs averaged across gives you the exertion-velocity (E-V) relationship. This E-V relationship is transformed just like the previous relationships to give us the RPE-velocity relationship (RPE-V). Essentially three rounds of data collection to give us five different relationships. And you have to do that for every lift you plan to autoregulate. 

So if you have 15 movements to be used in a macrocycle, that's 15 movements to map out. That initial investment of time is pretty large though. In theory, you should have your competition movements repeat every macrocycle so the data could roll over with very little update. So that's 12 movements, which is still an incredible amount of investment. This is also why I introduce movements into follow on macrocycles slowly. Rather than having only 3 movements carry over, I usually have three-quarters of my movements from my last macrocycle repeat into the next one, so roughly just 4 movements. Exercise selection is a whole different argument, and I'm neither a huge believer in variety for variety's sake or hyper-specific training. Or you could use deload weeks between cycles much like I do and make them testing days since the volume is fairly low. You could cap intensity for load-velocity testing at 80%, and I doubt a single at 80% is going to be a huge hindrance to your recovery.

But really, one of the great advantages with this is you may only need this one relationship, depending on how you use it. Using just E-V, you can set a rep goal, like 8 reps with 2 RIR (or /2 fail, or a 10RM for 8 reps, or 8 RPE - pick your semantics). You can then get within the 2 reps based on the linear relationship between E-V and RIR. For heavier lifts where fewer reps are possible, it's even easier to determine what the opening velocity should be. But now it just sounds like you're doing exactly what RPE advocates always say: base your autoregulation off RPE, but adjust with external feedback like VBT.

If you're going for straight up training wheels to get you from VBT to RPE, this is probably the way to go. If you also wanted to run an RPE program as a VBT ideologue, you could transliterate the E-V data into RPE. 


Previously I mentioned using INOL to gauge the number of reps per lift in a session. This was generally my attempt to control for training stimulus regardless of intensity used. While I think INOL is quite effective in regulating intensity and volume in proportion, they really don't say much towards your proximity to failure. Three sets of five reps at 60% is regarded the same as one set of fifteen reps. Because of this, it's obvious that INOL somewhat ignores proximity to failure, or exertion.

New reader, what this? INOL attempts to gauge training stress/stimulus through an equation. It takes into account the number of reps and intensity of the lift. This gives you an arbitrary number that you can use to determine if a "volume day" is as taxing as a "heavy day." This is covered and linked to in previous articles.

Furthermore, the blending of INOL and VBT is somewhat dubious at best. INOL is more theory than substance, and any modicum of its substance is relative to percent based training, not VBT per se. This detail may be beside the point, especially if your autoregulation isn't changing load by more than 7.5%. To confound the issue even more, INOL is supposed to be a planning tool, not an autoregulation tool. Maybe you can figure out some sort of system with hand-wavey reverse look ups, but maybe you're over-complicating it. 

Regardless of intensity, I see additive value in regarding each set in the perspective of proximity to failure. RPE does exactly that, where 1x @8 RPE is essentially one rep with two left in the tank, or more concisely a 3RM done for 1 rep. Why does a rating system matter though? Why does it matter to talk in "proximity to failure" terms or RPE terms?

Mike T's recent summit at powerlifting university 2017 shined some light on this that made me take it more seriously. Much like INOL, Mike had created a system of coefficients that weighted the training stress of each set. For example, @9-10 RPE (no reps left in the tank) was 1.33, @8-9 was 1, @7-8 was 0.8, and so on. You can add all weights across a movement within a session or within a week and compare it to some ballpark guidelines. Whereas INOL weights reps according to intensity regardless of proximity to failure, Mike T's training stress index weights exertion by sets. Granted, if you're measuring by a different unit, you should create bounds for those units.

For a single movement, Mike put forth 2.5 for an easy session, 3.5 for a moderate session, and 4.5 for a hard session. Much like INOL, it operates under the "single movement" clause, whereby the training stress of bench vs that of your squat aren't lumped together. It's not clear to me whether something like touch and go bench and feet up bench are arbitrarily separated, but you could argue it either way. For a training week, good planned bounds would be 14, 20, and 26, for the same rating scheme (easy, moderate, hard).

As I said before, this is all in reference to Mike's seminar on 2017 powerlifting university summit. I'd use the pictures or talk more in depth about it, but given that it was paid-for material and it's not my idea to share, I'd rather just give you the jist and refer you to buy access.

Unlike session rating though, this is separated by movement pattern with all squat type movements lumped together, etc. I may have misunderstood this, to be fair. Much like the INOL theory though, these guidelines could vary from individual to individual. This makes sense though given it's a proxy for work capacity, and work capacity is more of a moving target than it is a fixed point.

I like this application because everyone talks about work capacity when there's seems to be little agreed upon measure, normative values, etc. Work capacity is essentially a working theory. Mike Israetel talks about maximum recoverable volume (MRV) and maximum adaptable volume (MAV), which sounds much like work capacity as well. Mike T's training stress index also meshes pretty well with MRV terms of understanding how we manage lifting schemes.


Another good reason to consider RPE methods of the E-V table is the inherent fallacy of velocity loss. I've said before that velocity loss can be misleading. At very high percentages of 1RM, the threshold of 20% velocity loss (or 40% even) is below your minimum velocity threshold, or your last rep in the tank. Following the velocity loss rules to a T guarantees one of two things: 1) blunt force adaptation or 2) getting stapled.

Velocity loss is a VBT concept that strength adaptations occur from training where only 20% velocity is lost. Training with a loss of 40% of opening velocity is better from hypertrophy. It's sort of a minomer since you can perform both 85% of your 1RM to a quarter of velocity loss or 60% of 1RM to a quarter of velocity loss - with one of those better contributing to strength development. What is really hard to do is to get 20% velocity loss at sets at 90% and above - even if you can bang out 5 reps at 90%.

Even if you think E-V tables are too much additional work (when really they can be the only VBT data you record, ignoring all others), you still have to remember your MVT for these situations and have a general sense of how much velocity you usually bleed off in your final reps. If your final rep or 1RM moves at 0.24 m/s and you hit a rep for 0.27 m/s, there might not be another rep in the tank for that set. The next velocity decrement could be below your ability to power through. Alternatively, 0.27 m/s could just be noise - and you should plan around that. The only method you have to rebut this without this information is by going by subjective opinions on whether you can complete the next rep - which sounds exactly like what RPE is trying to accomplish. 

Furthermore, E-V tables allow another programming strategy that ignores percent of 1RM. This might be useful for movements that have no real 1RM as well - like your rear foot elevated split squat or other supporting exercises. 1RM for those lifts may never be tested, may be implausible/unreliable to test, or pointless. Rather than using percentages, you can undulate by number of repetitions if you know your E-V. If you plan to hit sets of 8 with 2 reps before failure, you can use E-V to determine appropriate starting velocity.

Or you can do what I do: not really care about the autoregulation, hit a fixed number of reps and sets, and make sure it's heavy enough to be hard. It's an accessory - not existentialist theory. Just do the damn work and be done with it.

While I've so far been an advocate of autoregulated volume and intensity, you can use this to truncate your autoregulated variables or control for number of lifts (NL). 


I hope after reading through this you've understood that VBT is king of all of the dingle-dangles. Not really, but since this is a VBT-Powerlifting blog, it's sort of becoming of me to suggest it.

Others have shown a strong inverse relationship with velocity and RPE. RPE and AMRAPs are the most common autoregulation techniques. VBT can be used to augment RPE, and is most commonly used that way. Likewise, AMRAPs can be used in conjunction with VBT as well. These three methods tie together on multiple levels, providing more forms of feedback. Brandon Senn explains this process really well in his article about the Autoregulation Book of Methods.

Which system or combination of systems is best is really user dependent. Even a staunch VBT advocate should be able to see some redeeming qualities in RPE. More importantly, autoregulation training methods are more similar than they are dissimilar in their application. Even if it's not your preference to use one system to drive the training process, another system will help analyze the process. The very obvious advantage that RPE or AMRAPs have over VBT is the bar for entry. Neither have price tag implicit to the process. I still do not feel required to win you over, but I hope I've alienated and emasculated all sides in this obvious shit post. 

Saturday, April 29, 2017

Reality Check: Accelerometer Systems Aren't Useless

I feel obliged to talk about why I don't discount the accelerometer systems in all cases. Firstly, I will remind you that the intent of this blog is to provide a powerlifting perspective on velocity based training. For perspectives other than that sport, I suggest seeking out other experts that will flesh out their opinions beyond 3 main lifts. In very simple terms, I'm interested in velocity based training as it pertains to fairly slow velocities, often emphasizing velocities above 80% 1RM. Secondly, I should also remind you that my first sensor comparison article is not a definitive study. The sample size is 1 (me). And lastly, there are practical reasons for using accelerometer systems. Axes measured is an important part of that, as well as different training modalities. There's always room for growth in these devices.

Anyone that thinks I'm trying to throw a manufacturer under the bus doesn't understand that I've kind of spread it around on all parties. The last thing I want is someone to look at the sensor comparison article or any article and use it as an argument to disparage a company. All of the companies out there are bringing something unique to the table and should be recognized for that. I'm not throwing shade. I'm not trying to hamper their efforts. Each of these devices has advantages and disadvantages.

Of the three companies I've included in my original comparison, I've spoken to a representative from each (PUSH, Beast, and OpenBarbell). At one point in time, I was even a blog contributor for PUSH. If I was indeed bashing accelerometer systems, why would I ever work for PUSH?


This is the most important part of VBT for strength training. This is not the most important part for all training. Even in strength training, VBT is not the most essential way to monitor, augment, or otherwise manage your training. I've said it before:
If VBT is the most important part of your training plan, your training plan probably isn't good.
That said, if you want to use VBT for strength training, then you will certainly need a device that measures reliably at slow velocities. It does not need to measure accurately, but it must be done reliably.  Accelerometer systems seem to work best above 0.40 m/s or around 80-85% 1RM on many lifts for average folks. Tethered systems (or linear position traducers - LPT's, optical rotary encoders, etc) tend to work reliably around this range for barbell movements. That does not mean they are without fault.

I'm not an engineer, so I can't really talk with great confidence about the full range of capability of accelerometer systems. That said, I have seen systems that use hardware that plausibly should be capable of measuring velocity below 0.40 m/s. If the hardware could measure it but isn't actually returning reliable measures below that, I would surmise this could be an issue of how the signal is processed or broadcasted. All of these devices work through Bluetooth and all seem to perform better on iOS (Apple) devices because of how Bluetooth low energy works on Android (protip: at least buy an iPod if you want less Bluetooth frustration). Additionally, it seems plausible that data can be bottlenecked by the constraints of Bluetooth, limiting their full capability. If Bluetooth was the limiting factor, that's truly a sad state of affairs because 1) the manufacturers are limited by developments on the smartphone end and/or 2) future iterations of the devices must be developed to keep pace with signal broadcast if Bluetooth is the limiting factor. The upside of this is manufacturers could alter the way the signal is broadcast, providing real-time information in short bursts and transmitting extraneous detail after completion of the recording period (after your set).

The other limiting factor could be related to how frequently data is sampled and processed. If this is the limiting factor, the great hope is that manufacturers can update the software end to mitigate this. Anyone that's an early adopter knows this experience. Most devices within the first year of the commercial release act buggy. It isn't until after some time that these issues fall by the wayside. You should keep this in mind when you're looking at accelerometer device reviews on youtube from over a year ago, or even the comparison data I provided in future time.

When I fault devices for not performing well with deadlifts, the common response is some people CAN get deadlifts to work with the device. It usually involves performing the movement in a special way that is arguably too far away from the mode of training to make it feasible.  And just to be clear, I haven't talked to a single manufacturer that was satisfied with how their device was assessed for deadlifts. Maybe there isn't a good solution, maybe deadlifts behave erratically, maybe my consistency in deadlifts suck, or maybe my attempts to measure deadlifts objectively are flawed. Could be any single one, or it could be all of them.


Powerlifting barbell movements are predominantly in 1 axis, but you could argue that all movements happen in three axes enough for it to warrant attention. Even the bench press, which moves in two axes more than the others, doesn't seem to be hampered by measurement in one axis alone. Different devices measure in a different number of axes. Most devices allow for a change in configuration so you can measure in an axis/axes of your choice (floor/ceiling/horizontal mounting). S

That said, depending on what you're doing for assistance/accessories and how much VBT integration you intend to have, it might be advantageous to choose a purpose driven implementation of a VBT device. In particular, lunging in general (side, traveling, and possibly forward/reverse lunging), some types of landmine work, step ups, glute-ham raises, pull ups/chin ups, could be limited by your device selection. 


Consider how much a GymAware cost. At a price tag of $2200, that's not including a subscription. Next, pricecheck a Fitrodyne Tendo or a T-Force unit - don't forget to consider how convenient these set ups are. Last check on the tethered-unit supremacists: tell me the next estimated ship date for OpenBarbell V2. Compare this to the availability of accelerometer systems and they obviously have a leg up. Accelerometer systems have a more favorable equilibrium on both supply and demand.

Just as much as I recommend using some form of autoregulation training before jumping into VBT, I would also recommend incremental implementation of VBT devices. I would recommend trying a product out that has a solid return policy or using one from a friend/facility that already has one. Alternatively, you could minimize your losses by buying at the lower end in terms of price if you weren't sure if you wanted to take the $2200 dollar dive.


Don't assume I chose the best design method. I didn't. I went with what was practical and tolerable in order to develop a rationale for my case to implement VBT. The target was the consumer market. The only other comparison of multiple devices I've seen talk about them in generality, occurred long before the devices were well-established (IE: before they worked out the major bugs), or simply stood as opinion pieces. I don't think any of these really helped people determine which unit to buy.

If you think I'm going to toss out my PUSH now that I have an OpenBarbell, you're wrong. Depending on what I mean to do, the PUSH still comes out.

This isn't a validation study. At best, the comparisons are akin to what DC Rainmaker for cycling power meters or NotebookCheck does for laptops. At worst, it's little better than Men's Health reviews or Gizmodo.


Accelerometer systems aren't garbage in all things lifting. Accelerometer systems may not even be the worst option in all things. In the end, it's almost like asking what's a better motor vehicle: a Prius, an F150 truck, or a Formula 1 racing car? Depends. Are you focus on commuting, hauling cargo, or getting from point A to B in the least amount of time?

Friday, April 7, 2017

A Powerlifter's Guide to VBT Pt 6: Personal Preferences and Personality (or lack thereof)


I currently make no money off this blog, so there's no incentive to make regular updates. Recently my internet's been out. I live in a rural area where getting an internet technician out to fix things takes about 2 weeks. That sounds like a fine excuse, but congratulations to the North Carolina Tar Heels on their 2017 championship run #Redemption


I've nailed the point that VBT is not the best way for every given individual to train. It's my personal preference. I think there are certain ways and particular individuals that can excel at training with VBT in part or as a whole. So far as I know, I happen to be one of them. I don't think you need to be as inquisitive about your training as I have, track extraneous details of your lifts, or even be bound to a laptop and device to make your training effective. This will lay out the types of individuals who could benefit from training, based on responses to training, attitudes about training, or based who they picked in their bracket for the final four in the 2017 NCAA tournament.

The Grinder

In a phrase: suck it up, buttercup.

Good day or bad day, the bar speed doesn't lie. Just buck up and do the damn work. It helps to be passionate about your training, but it also reminds me of some Army leadership principles. Army leadership is defined dogmatically as providing purpose, direction and motivation. Apparently, motivation is really important. In a very cold manner of thinking, it also defines motivation as "getting others to do what you need them to do." At the end of the day, it doesn't matter if you enjoy your volume or intensity, but rather that you get it done. I like to think about this as being an adult about your training - not to demean other attitudes. Having your own place is nice. Paying your own bills is not. 

Greek myth toiling without end, or
strongman that sucks with atlas stones?

When we use objective measures, it's helpful to keep yourself accountable to your capabilities. You might not have slept well last night, might have personal issues at home, but if you stop feeling sorry for yourself you might be able to get under the bar and do some productive work. After working with VBT for long enough, I've found the effect size of how poorly I feel from whatever stressors have little impact in my training performance. Then again, maybe the Army made me dead inside and the only thing that phases me is not getting enough food a day.

It's easy to get into your own head and convince yourself you are ill-prepared or better prepared than you are on a normal day. Every piece of feedback helps paint a picture of your readiness. These can be objective/subjective and internal/external. No feedback system is infallible, but it helps to have more than one check on readiness and performance. 

The Breadwinner

In a phrase: earn your keep.

A coach I know had this maxim that some athletes have to train good to feel good. This has sort of a breadwinner attitude: do work, make dividends. It's hard to see what those dividends are when your progress is slow, but you can see glimmers of it through your training with velocity. If you perform well, you get to/have to do more work. If you perform poorly, you get to/have to do less work. This cuts both ways with volume and intensity. That part of getting to or having to do work more with volume or intensity depends on your perspective. You're held to a standard, and you are rewarded/punished for your performance, again depending on your perspective.

This idea can cut any which way along intensity and volume tolerance. If 80% of 1RM moves faster today than it usually does: you've earned more intensity. Maybe only somewhere near 5% more, but strike the iron while it's hot. If you keep knocking down set after set without any major declines in opening velocity, you likely have a better tolerance for volume.

The Failure Adverse

In a phrase: don't be effort adverse, just be failure adverse. Try trying.

I largely disagree with this point in general with auto-regulation training. Auto-regulation doesn't remove the potential for failing a lift. It doesn't remove the possibility of injury. Those things are still there, but auto-regulation training puts sign posts along the way. You may recognize them and avoid disaster, but you may not.

Firstly, I disagree with the common assertion that injuries in powerlifting are from max lifts and acute trauma. Anecdotally, most injuries are from cumulative stress over time, training and non-training. In many cases when you see injuries from singular events, it tends to be the straw that broke the camel's back rather than the crossing the injury rubicon.

That said, here's the sign posts I read that bad times are coming...

One thing I notice is inconsistent velocity with a lift that is usually predictable. Misgrooves are often represented in your velocity output. In a higher rep set, you'll often see a few outlier velocities. Sometimes you can chalk it up to re-taking your air for longer sets, but sometimes it's very obviously just sloppiness in your movement.

Another inconsistency in velocity loss across the set is a rapid deflation of velocity. If your set starts at 0.52 m/s, drops to 0.48 m/s on the next rep, then nose dives to 0.30 m/s, you have a number that shows your proximity to grindtown - population: you. Sometimes you know that 85% (or today's 85%) should give you X reps, but sometimes your fuel tank leaks. You'll find you don't have as many reps to carry you on as you normally do. These two examples can be measured and might prevent injury, but they're not the most likely or most useful way to prevent injury in an athlete monitoring sort of way. Chances are, you're going to get obvious, subjective indicators that tell you what's happening without velocity telling you what's what.
This reminds me of a period of time after I had a slap tear. I thought I could train around it, but it was pretty obvious it was a persistent injury. Inside of the first 3 reps of my working weight my bar velocity really dropped off. There's probably a mechanistic reason for this (something about the Golgi tendon organ inhibiting contraction, I guess), but the utility in getting that granular is meaningless if you're not willing to accept there is an issue and you need to do something about it besides work around it. Often, outcomes are easier to act upon than diagnostic criteria.
I think the better utility is in finding whether fatigue is chronic or acute. Chronic fatigue is built up over time and can be a sign of over-reaching and over-training. There are many signs to this, but many misdiagnose subjective feedback (how you feel, mostly) as the sole indicator. Many people chalk about their feelings as a sign of overtraining, which is not the case 9 times out of 10. This is probably why many people scoff at the implication of overtraining, because most only diagnose it based on internal, subjective feedback (feelings). I would think it's more helpful to have at least one objective indicator to back up the claim. If you're consistently downregulating intensity or volume with velocity, it could be a sign of a necessary deload week to allow better recovery and improvement in training quality. I guess you could use other things, like feeling tired throughout the day, sleeplessness, elevated blood pressure, or whatever criteria that varies from person to person. My preference is to again rely on outcomes, letting outcomes serve as diagnosis.

If you really wanted to understand whether your fatigue is chronic or acute, I would check standardized load velocity. In a previous article, I advised starting a session with a squat or a bench at a given load every time. Usually, I try to keep it at a light to moderate load, something I know I normally hit for 0.5 m/s on a bench press or 0.65 m/s for a squat. It's even better if you make this pinned movements (pin squat or pin press), since that removes a lot of the variability that could comes from mis-grooving or other performance confounders. You can compare your velocity against short term or long term averages (somewhere in the neighborhood of the last 10 measurements and the last 4 month's worth of measurements) and see the magnitude of difference. You could wrap this into a larger athlete monitoring program, but that's beyond the scope of this. For a cheat sheet on this, check out TRAC at Reactive Training Systems.

The Masochist

In a question: how can I drown my lifts in volume and frequency without killing myself?

Two things I love are volume and frequency. They work for me. The issue with having fluctuations in volume is the fatigue can be unpredictable depending on how your structure your program. I also love high-frequency training, especially for bench press. The great part about auto-regulation is you can scale according to how each lift is responding to adaptation. Of course, the long-term goal is to find out the right combination and amount of training variables (volume, frequency, intensity, etc), but short of having that you can just auto-regulate as necessary. 

The argument here is pretty much the same as the grinder, but the personality type is more suited to the person that looks forward to inducing fatigue. 

The Accountant

In a phrase: you're so numbers driven, you're double majoring in statistics and exercise science.

Playing with volume and intensity gets your rocks off. You have your own scheme to weight values appropriately and periodize to some statistical model. Subjective feedback is cool, but you if it's not quantitative it's not good enough for you. You won't do a workout without filming your top sets, measuring velocity, and updating your worksheet. Before you go to sleep, you think about new ways to quantify your training data and lose sleep if you don't get it started right away - unless that means you'll miss your training readiness quotas by undersleeping according to your baseline of hours slept in the last 10 days. You know all these factors has an effect size of only 2% increase in performance, but you're convinced that changing enough factors will give you the advantage you need in your next meet in the 22 kg class. 

You really don't need much more to add to your paralysis by analysis, but I know talking you out of it won't work. You don't need VBT to make gains, but you also don't need a premium google analytics account and you have that too. I'm pretty sure even your dog hates you.


There's a number of personalities and attitudes that mesh well with VBT. I don't think it makes much sense to shop around for auto-regulation methods based on personality. Chances are you can be one of Mike T's controlled-aggressive archetypes and still find success in VBT. Chances are, one of the above can describe you and you might not get much out of it. I really don't think personally factors into VBT auto-regulation that much, but I do think it's a factor for RPE.

Some people tend to emphasize the importance of increasing training arousal (getting hyped), while others tend to emphasize stimulation avoidance. I don't think being hardline on either one is important, realistically sustainable, or influences the training process significantly to any degree. In the end, I think attitudes about your training don't matter as long as you can make some use out of objective feedback.

We're nearing the end of this series. This one is mostly fluff that responds to criticisms about VBT that I think are erroneous or over-emphasize the importance of personality and mood in training. The next one will be a case study of programming with VBT in comparison to percent based/nRM based programming. I only plan on doing an RPE themed one after that, and this will slip into irregular updates.