Can Everybody Benefit From Exercise?

Ain’t that a click-bait title? (Slightly above 1.600 words, estimated reading time: about 8 min.)

I am by education an analytic philosopher and a logician. Analytic philosophy is really glorified common sense. It may not always be useful but even when it’s not it on occasion be entertaining.

Logic is more specific and is concerned with statements featuring every or some, if… then…, and, or and not, a well as therefore and true and false. So consider the following statement:

(A) Everybody can benefit from some exercise program

Logic and analytic philosophy common sense are all we need to discuss (A) and answer the titular question, but I’m going to throw in some science in the mix because it’s always better than just philosophy.

As always with philosophy, the journey matters more than the destination. Eventually, the titular question will remain open. But bear with me and enjoy the ride, and you will be rewarded for your time.

Or not.

Logic

If some program is an arbitrary program chosen from a menu of available options, the logical form of (A) is:

For all x and y,
if x is a person and y an exercise program in the menu, then x can benefit from y

and (A) really means:

(A1) Everybody can benefit from any exercise program in the menu.

If the menu encompasses all possible options, counterexamples to (A1) abound. Any exercise program for competitive athletes in any sport would wreck havoc on a beginner. Conversely, a beginner’s program would not even maintain a competitive athlete’s skills and condition. Thus, (A1) is obviously false (at least if the menu is not suitably restricted).

A more acceptable logical form would be:

For all x there is a y such that
if x is a person and y an exercise program, then x can benefit from y

and means something like:

(A2) Everybody can benefit from some exercise program or another

(A2) seems intuitively more plausible than (A1) — after all, even bed-ridden accident victims can benefit from exercising any limb they can move. And yet, proving it would require ruling out all possible exceptions. An analytic philosopher could probably devise a thought experiment contradicting (A2). Thus, odds are that (A2) is false as well even if it is only by virtue of highly hypothetical cases.

Common sense (I)

Jane Average is not an analytic philosopher, but a forty-something who is now working a full-time desk job, has a family, etc. She was reasonably fit in high school, but she has little time to exercise nowadays.

Until recently, she did not think much about it, but when the elevator at her workplace stopped working for a day or two, she had to climb the stairs and began to breathe heavily much sooner than she would have expected.

That day, Jane had an epiphany: she needed to get back in shape.

Jane does not care whether (A2) is true in general. Jane wants to know which y would make (A2) true when x = Jane.

Unfortunately, (A2) only assumes that x is a person. And there is much more to know about x to choose y. Like, for instance, x‘s current baseline level of physical activity, strength, and conditioning.

If Jane heads to the nearest commercial gym or hires a personal trainer, she might be proposed a test, assessment, or whatnot, of her current ‘general fitness level’. But there’s an issue that she might be unaware of: every fitness test is skill-dependent.

The consequence of this is marvelously illustrated by Pavel Tsatsouline in a short discussion of the overhyped notion of work capacity. In 1947, a Swedish study measured the Physical Work Capacity (PWC) of ore smelting workers by testing their performance on ergometers (stationary bikes). As Tsatouline comments,

A bicycle racer would leave a blue-collar worker in the dust. Then the latter would invite the former to hang with him for a shift at the steel mill.

The upshot is that the PWC test is a good proxy for bicycling work capacity, but not for ore-smelting work capacity. Or for Jane’s general fitness level, for that matter.

And yet, nowadays, VO2 max tests — which are really standardized version of the 1947 PWC test — are routinely used to assess ‘general’ fitness level, as my gym does (it’s in Swedish, but Google Translate does an OK job on that one).

Now, if we know that Jane has a hard time with stairs, do we really need to know her VO2 max?

VO2 max measures the tolerance to specific loading parameters (the resistance of a stationary bike or the speed of a treadmill over a given time interval), but these loading parameters are of little relevance relative to Jane.

Knowing how many stories Jane can climb before she begins to breathe heavily would be enough of a proxy for VO2 max for choosing a cardio protocol suitable for her. But there are other loading parameters that should be considered before designing an exercise program for her.

And if Jane joins my gym, they won’t.

Biomechanics

The notion of tolerance to load was introduced in biomechanics by Dr. Stuart McGill, and is derived from the notion of engineering tolerance.

The tolerances of a physical system engineered to perform a given function represent the amount of disruption the system can tolerate before it becomes unable to perform the function it was designed for.

This may sound very abstract but is easily illustrated with the example of a suspended bridge crossing a river.


The structure must be capable of withstanding, in addition of its own weight, winds (blowing against the cables, suspenders, and towers), traffic on the deck, water current (against the towers).

All of the above induce cumulated vibrations that the construction as a whole is capable of damping, that is, of distributing and dispersing over cables, suspenders, towers, and anchorages. How much vibration the suspended bridge can damp depends on how much vibration each of its parts can withstand on its own, before it has to offload some to a neighboring part.

Simplifying somewhat, the amount of vibration that a part can withstand on its own determines the tolerance of that part. The tolerances of the whole bridge is thus a function of the tolerances of its parts.

If the tolerances of each of the individual parts were met or exceeded at the same time, the structure would become unable to disperse the cumulated vibration. The oscillation of the deck would make traffic impossible, and the bridge could not perform its function. A historical example of this phenomenon is the collapse of the Tacoma Narrows bridge in 1940.

Spinal load

Human beings are not bridges, but biomechanics looks at the human musculoskeletal system in the same way as an engineer would look at a bridge.

Of particular importance is the biomechanics is the spine. Issues that have their origins in the spine often have manifestations in the limbs and vice versa. Unfortunately for many, spinal issues and limb issues often reinforce one another, resulting in positive feedback that increases their magnitude.

If you don’t follow the link, here’s the skinny: ‘positive’ does not mean ‘good’ but ‘increasing’. For instance, positive feedback is responsible for the collapse of the Tacoma Narrows Bridge. Similarly, positive feedback reduces the spine’s tolerance to failure, as illustrated in Fig. 2.

Tolerance_Failure_1

As the caption makes clear, the discrete loads being moved (here, boxes) are well below initial baseline tolerance. But under fatigue failure tolerance decreases. Eventually, the initially safe load becomes sufficient to induce failure (e.g. herniation). In the above particular case, poor movement mechanics (a flexed spine) accelerates the process.

Tolerance_2

Fortunately, baseline tolerance to spinal load responds well to training. Furthermore, because of the relation between the spine and the limbs, improving the spine tolerance has a positive impact on the musculoskeletal system as a whole.

Common sense (II)

One the one hand, determining Jane’s VO2 max or even a close approximation would be overkill. On the other hand, it makes the PTs look like they know their exercise science, and it may motivate Jane to stick with the program they’ll hand her.

But Jane’s VO2 max is much less relevant for program-design purposes than her tolerance to spinal load. Or the stability under load of her ankles, knees, and shoulders. If the PTs at Jane’s gym are like the PTs at mine, they do have a proxy for some of the above that they call ‘functional fitness test’ and involves Bosu and Swiss balls.

Unfortunately, biomechanics teaches us that stability has little to do with balance. In fact, training on unstable surfaces may actually precipitate tolerance failure if one’s baseline tolerance to spinal load is too low.

And Jane’s probably is, if she sits, drives or commutes a lot. And so are her tolerances to knee, ankle and shoulder loads. If it is low enough, she would actually be better off not following the routine the PTs gave her. Merely trying to climb stairs and carry grocery bags more often would be enough.

Conclusion (for today)

If you are a casual gym goer, Jane shares some characteristics with you. Conclusions that apply to her also apply to you. In short: ditch stability training, climb stairs more often, and make loaded carries a staple of your training. Learning some biomechanics won’t hurt, either.

If you are a professional athlete, you may be tortured with ‘functional training’. Joe De Franco has a thing or two to say about it that I don’t need to repeat here. Check it out but be warned: it may cause you to reconsider your relationship with your coach.

If you are a more seasoned gym goer or even a serious amateur strength athlete, and you have managed to steer clear of nonsensical exercises, pat yourself on the back.

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Image credit

[Fig. 1] Robert Lamb & Michael Morrissey “How Bridges Work” 1 April 2000. HowStuffWorks.com. Retrieved 15 June 2017.

[Fig. 2 & 3] Dr. S. McGill Lower Back Disorders: Evidence-based Prevention and Rehabilitation, 2nd ed., 2007, p.13 & 14.

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