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?

MEASURING SLOW VELOCITIES

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.

TETHERS AND AXES

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. 

EQUILIBRIUM PRICING

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.

IT'S A COMPARISON, NOT A STUDY

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.

(NOT REALLY A) CONCLUSION

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?

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

A BRIEF SIDENOTE

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

INTRODUCTION

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.

Conclusion

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.