Accelerative Training

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1 Accelerative Training MILO 6(1): 112-120, 1998. Steven Plisk It’s generally understood that a certain threshold of training intensity is needed to effect positive adaptation, but many athletes and coaches still believe that resistance must be sufficient that the weight can’t — or shouldn’t — be moved very fast. I intend to challenge this proposition, and to make a case for the fact that acceleration is the name of the game even when executing basic structural movements (e.g. the squat and dea
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   Accelerative Training1 AAcccceelleerraattiivveeTTrraaiinniinngg  MILO 6(1): 112-120, 1998. Steven Plisk It’s generally understood that a certain threshold of training intensity is needed to effect positiveadaptation, but many athletes and coaches still believe that resistance must be sufficient that the weight can’t — or shouldn’t — be moved very fast. I intend to challenge this proposition, and tomake a case for the fact that acceleration is the name of the game even when executing basicstructural movements (e.g. the squat and deadlift). It’s really just a simple matter of understandingthe fundamental nature of force, and of putting this concept into practice regardless of task or workload. F=m·a Revisited  At first glance, “force is the product of mass and acceleration” appears to imply that there is no force without motion (or vice-versa), but that’s not necessarily the case. For example, since gravity isexpressed as an acceleration constant [~9.8 m/sec 2 ], a vertical force of ~980 kg·m/sec 2 (orNewtons) would be required to hold a 100 kg barbell in place statically.Despite the apparent simplicity of F=m·a, the inability or unwillingness to grasp its functionalsignificance is an underlying cause of the nonsense taking place in many weightrooms. This conceptis neither contrived nor trivial, and shouldn’t be tucked away in a physics textbook until needed tosupport some abstract opinion. In fact, it’s a foundational principle upon which all motion is based(with strength training being no exception). When you consider that any movement is essentially anact of defying gravity — which itself is an accelerative force — the central issue becomes: What is being moved, and how fast? Athletes apply (or defy) gravitational acceleration through a wider range of forces than non-athletes, and their success or failure in executing a particular task is almost always determined by the ability to achieve a critical velocity or power output. Simply stated, the object must be movedthrough an optimal acceleration path within a certain time period. Powerlifting is an example of aniron game that’s close to the low-speed end of the spectrum, whereas Olympic-style weightlifting isrelatively nearer to the high-speed end. Track & Field throwing events are additional examples of high-velocity power sports. Regardless of whether or not one pursues either of these competitively or performs such movements in training, the salient point is the same for each: Maximal force(relative to one’s strength capabilities) is only generated if the object or implement is maximally accelerated. Aside from the obvious fact that heavy weights cannot be lifted as rapidly as light ones— and that some movements are inherently ballistic, where the weight or body is launched, whileothers are not — this has two other fundamental implications:    In terms of injury prevention, strength development or athletic ability, rate of forceproduction is as important — and trainable — as magnitude. Movement execution timedictates the amount of force, and in turn power output (the rate at which work is done), thatcan be generated at a particular workload. Many lifters mistakenly believe that rate of forcedevelopment is only relevant during ballistic movements, but not in basic weight trainingexercises where the bar isn’t released. As we’ll see, however, brief application of peak forcemay not be such unfamiliar territory in the weightroom after all.    In terms of training effect, it has been shown that the intent to move a weight explosively can be more important than actual velocity achieved in doing so. Full volitional effort —i.e. a deliberate attempt to maximally accelerate the resistance, even if it’s too heavy to moverapidly — yields the greatest neuromuscular activation and subsequent adaptive response.   Accelerative Training2 Lest you think that I claim to have pioneered the idea, compensatory acceleration (a termcoined by Dr. Fred Hatfield) has been a way of life in the training of European athletes fordecades without being named as such, but with obvious success. Consider the resourcesaddressing this method of training for power and rate of force development (Aján & Baroga,pp. 161-176; Hartmann & Tünnemann, pp. 138-223; Schmidtbleicher [in Komi], pp. 381-395). Admittedly it’s not difficult to find “experts” who will endorse any empirical training concept ormethod, which is precisely why fundamental principles must be used to measure their worth. Butany way you slice it, submaximal levels of force production and neuromuscular activation — which, by definition, are what occurs when a given resistance is not accelerated to the limits of one’s ability — simply don’t make sense as a viable or productive means of training. This brings me to my nextpoint. Activation Modulates Adaptation Rapid movements aren’t the only way to activate — and train — fast-twitch muscle fibers. Likewise,the notion of distinct fiber types is obsolete, since motor units (individual motoneurons and thefibers they innervate) actually exist in a spectrum; and are progressively recruited as power outputincreases. Given the virtually infinite number of force-velocity combinations possible in any movement, it’s not surprising that the neuromuscular system activates motor units (as well asmuscles) in functional task groups.It’s important to understand that force production isn’t just a matter of recruiting motor units, but also of coordinating and synchronizing them. Once again, the operative concept is task specificity. Without going overboard, I would like to make a few interrelated points: The highercenters of the neuromuscular system that govern this process are as plastic as the muscle fibersthemselves. This is all fine and good — if utterly esoteric — until one also appreciates thatadaptation is a function of activation; and that maximal effort at a given resistance is the meanstoward achieving it.Furthermore, adaptive tissue remodeling is as much a response to motoneural signals as it is asimple cellular repair process (case in point: graft the nerve of a type I [slow-twitch] motor unit ontoa type II [fast-twitch] muscle fiber, or vice-versa, and that fiber’s properties proceed to reversethemselves). Indeed, to quote Siff & Verkhoshansky (p. 4), “the fundamental principle of strengthtraining, then, is that all strength increase is initiated by neuromuscular stimulation.” However, beforewarned if you endeavor to read this book — it’s extremely comprehensive and detailed, and you’ll have to swim hard!Practically speaking, we have so many options in terms of workloads and repetitions that thepossibilities seem almost endless. Intensities ranging as widely as 50-100%, with reps from as highas 20 to as low as 1, have been successfully implemented and advocated. Yet despite all thesechoices, we’re still selling ourselves short if we:     Approach strength training exclusively in terms of weight and reps, while ignoring theaccelerative quality of force;     Assume that full activation automatically occurs whenever the bar is moving; or     Wait for the last rep of a set to trigger the desired training effect.These are particularly costly mistakes for those who abbreviate work volume to the point wherethey can’t afford anything less than extreme emphasis on training quality. The solution is tomaximize force output and neuromuscular activity on each repetition by accelerating through the   Accelerative Training3 sticking point at full power, regardless of resistance or rep count. Before proceeding to the practicalaspects of this concept, however, we need to re-examine how the sticking point figures into it. The Sticking Point Revisited It’s interesting to consider how this subject ties in with the issue of rate vs. duration of forceproduction. For purposes of discussion, let’s assume that the ascent phase of the squat or deadlifttakes about 1-2 seconds to execute (fatigue and/or 1RM attempts notwithstanding). The stickingpoint is that region in the range of motion where leverage and resistance interact to create thegreatest difficulty in moving or controlling the bar. In this case, it’s ~30° above the parallel position. As is the case with most multi-joint exercises, it occupies a small portion of the movement; but may in fact occupy a relatively larger part (perhaps as much as 1/3 – 1/2) of the time required tocomplete it, especially as resistance increases and/or exhaustion sets in. In any case, maximal effortis not required over the full distance and time through which the bar is moved. Figure 1. The classic F-V curve: the solid line indicates peak force that can be developed atvarious muscle action velocities (note concentric < isometric < eccentric F max ). Power isindicated by the dotted line, where concentric P max tends to occur at ~30-50% of both F max  and V max . Source: Åstrand P.O. & Rodahl K. Textbook of Work Physiology (3rd Edition).New York NY: McGraw-Hill, 1986.   This last fact has fueled an ongoing “control vs. momentum” debate. Without gettingsidetracked, I simply want to mention that the anti-acceleration school of thought — where velocity supposedly defeats the purpose of lifting weights — is neglecting a key fact: Gravity continues actingon the bar as it picks up vertical speed, and the athlete must continue applying force in order to keepit moving or accelerate it further. While it’s true that force output capability decreases as muscleshortening velocity increases ( Figure 1 ), the notion that momentum takes over and does the work    Accelerative Training4 at high speed is nonsensical. In fact, power production usually peaks somewhere in the 30-50%range of maximum velocity and/or force, depending on the movement. This doesn’t mean that weshould abandon heavy weights. It does mean that the range of productive training intensitiesextends well beyond the slow squeeze zone.Furthermore, this concept doesn’t just apply to competitive athletes. The recreational lifter isalso well advised to implement it, especially as he/she reaches advanced strength levels and requiresmore potent and variable stimuli. Perhaps an analogy from automotive engineering is appropriatehere: The design of a sport utility vehicle stands to benefit more from the lessons learned in off-roadracing than a race vehicle stands to gain from those learned while driving around town. Figure 2. The F-T curve: force as a function of time in a total-body extension movement.Execution time may vary from 0.1 sec (e.g. the jumping movement illustrated here) to +1sec (e.g. a squat/deadlift). Peak force varies accordingly: the shorter the execution timeallowance, the lower the force that can be produced relative to one’s absolute strength inthat movement (represented by the dotted line); hence the need to develop force rapidly.Accelerative training improves rate of force development, resulting in a steeper curve andgreater impulse production (represented by the area underneath the solid line) and poweroutput (i.e. work per unit time). Source: Hatfield F.C. & Kreis E.J. Sports Conditioning: TheComplete Guide. Santa Barbara CA: International Sports Sciences Association, 1989. The relevant idea here is that the peak force generated in the sticking point region (despite its brevity) can be considered the primary reason for doing these movements in the first place. Arguably the lesser forces applied elsewhere in the range of motion (despite their duration) aresecondary. Once again, the implication is straightforward: As a general rule, the rate and magnitudeof force development at certain point(s) in a movement are fundamentally more important than thetotal distance or duration through which it’s applied. Collectively, this flies in the face of the so-called “time under tension” theory as well as the purposefully slow training methods and techniquesthat have arisen from it. However, it has obvious significance in training for activities whereexplosive forces often must be generated within 0.1 – 0.2 sec, during which the athlete certainly doesn’t move through a full range of motion (although the wind-up or follow-through of such
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