The Simplicity of Movement (Action)
There are only two things one needs to teach (condition) one's muscles to do: Achieve fullest contraction, and achieve fullest relaxation of that (any) muscle -- and every movement, will fall between those extremes.
That lesson is best taught by the premier muscle of the body -- which is the heart, because it always works so unfailingly, or life is no longer possible. But the objective of exercise (conditioning) is not simply to make the heart work harder and faster, but to enlist the other voluntary (skeletal) muscles of the body in aiding that critical function of circulation -- because the flow is only meaningful when one considers the end destination, and the complete circuit -- and not just the action at the heart, without any movement anywhere else.
However, such action is frequently seen in people kept alive by extraordinary life support technologies as is now possible -- initially conceived for temporary usage to make a full recovery possible -- but now also employed when recovery is not possible, and often to prolong vital signs to extraordinary lengths beyond the consciousness and enjoyment of life -- which a few insightful pioneers regard as the definition of a viable, sustainable and meaningful life -- which undoubtedly will be discussed at greater length and depth in the forthcoming years.
But way beyond that, one can ask the question, what meaningful actions (movements) can one take, that significantly enhances the optimal functioning of the human body -- not just to do trivial things, or the obvious things -- but to enhance functioning at its most critical level that underlies everything we are, and everything we do (health) -- that is largely taken for granted that we already do, when in fact, we have never even begun to carefully consider them.
Thus, we still have the arguments between those who should know better and those who don't, of whether exercise is good or bad, and moving beyond that (if possible), what would be the nature of the most productive manner of exercise -- not just to run faster, jump higher, and lift more weights, etc., but to do all those things -- when the brain functioning on its highest level of challenge, deems those maximal attempts and resources need to be employed appropriately, efficiently and effectively -- and not merely squandered as though it is an unlimited resource, and the more one uses, the more one gets.
Nothing in the real world works that way -- of unlimited use, leading to a further expansion of the resources, rather than its (premature) exhaustion -- so that in the learning (conditioning), one has to also calculate the proper reward-to-risk ratios. Preferably, that would mean jumping out of a plane with a parachute rather than without one, and cycling with a helmet rather than without one, following the advice of those who boldly proclaim, that what one does that doesn't kill them, will make them stronger.
So the problem of beneficial movements, is not whether one can achieve one extreme of muscular state (contraction or relaxation) to the exclusion of the other, but in one's ability to enhance the greatest articulation (expression) of that full range, while also increasing that range at its accustomed limits (extremes) -- as the fundamental measure of that change, and ability to produce it -- as deemed appropriate and necessary.
There are some who teach that the only action of the muscle, is to produce a relaxation response -- as in yoga, chi gung, relaxation and stretching (only) techniques, while others believe, that all one aims to achieve is muscular contractions at all times, not surprisingly accompanied with hypertension -- because the heart must pump into that unrelenting resistance. On the other hand, the perpetually relaxed muscles at the extremities particularly, do nothing to aid the circulatory process with its own alternating rhythmic contraction-relaxation phase -- that would effectively push the fluids back towards the heart more expeditiously, which is the beneficial health effect.
So it is not enough just to make the heart alone work more vigorously while the skeletal muscles remain largely inert, but more sensibly, to get the muscles that are not engaged, performing the most useful actions they can contribute to the basic maintenance of the healthful operation of that individual -- which is enhance the flow of nutrients to the extremities of their critical functioning at the head, hands and feet, while also removing the waste products that are the results of such exertions, in the release of that energy to move.
The problem in exercise, is that while moving, one may not be aware that the ultimate objective, is to achieve that awareness of that state of muscular contraction one is in -- because the state is not only determined by position, but also resistance. That is to observe, that even when 500 lbs is resting on one's chest rather than at arm's length -- that is not a state of relaxation and rest, because the resistance doesn't go down to zero -- but has to remain minimally, at 500 lbs. "Resting" at the top, is also 500 lbs. The difference between those two positions, is the power needed to move from the lower to the higher position -- but the lower position is not fully relaxed, nor the top necessarily fully contracted.
Despite the apparent movement, there is very little change in the muscular state -- usually beginning with contraction, and maintaining that contraction throughout -- despite apparent movement -- which is not the desired change of desired states from full relaxation to full contraction -- and back again, for a sustained period indicating that aerobic nature. That is the problem with doing benchmark movements such as chinups or parallel bar dips even without additional weights; that weight never goes to zero -- at any point during that set of repetitions. There is no resting (relaxation) phase -- but rather a prolonged anaerobic effort until one fails -- not because of muscle failure, but first because that lack of circulatory effectiveness is detected first by the brain, that will cease all further operations and efforts, until a healthful reserve can be restored to the brain -- which overrides every other functioning, movement and activities.
That was the rationale in the development of the Nautilus and other variable resistance machines -- that they would allow one to go from zero to 100% (and back repeatedly) -- but it also has to be used with that understanding, and not defeated by exerting twice as much effort against that natural relaxation phase -- which then prevents any relaxation from occurring and predictably, making failure inevitable and faster -- which is the last thing one would actually want to do, in any real world challenge, or more importantly, in real life -- which is also the problem of aging.