RATES AND FREQUENCIES OF MOVEMENTS
Stegeman, J. (Translated by J. S. Skinner). (1981). Exercise physiology (p. 261). Chicago, IL: Year Book Medical Publishers.
Some coaches attempt to improve the performances of athletes by having them increase the rate of cyclic activities, for example, rowers and swimmers are asked to perform higher stroke rates, and runners to increase the number of strides they take per unit of time. Such alterations may not have the desirable effects for which they are intended. Athletes have "natural" frequencies of movement that apportion their performance capabilities for particular events in an attempt to achieve the greatest economy of movement. Artificial disturbances of those movement frequencies could reduce performance economies.
In support of the concept of natural rhythms of movement Stegeman (1981) wrote ". . . subjects intuitively select the stride frequencies which are particularly economic" (p. 261). This means that there is a natural frequency of rhythmic movement that is appropriate for each athlete in each sport. Athletes should be encouraged to find that rhythm and then develop movement mechanics around that frequency. Unnatural frequencies will result in inefficient work being produced with a consequential loss in performance potential. Thus, before coaching an athlete to achieve a greater turnover rate of stroking or striding, consideration must be given to the possibility that doing an activity at an increased rate may produce an excessive cost to the movement's economy.
". . . From a physiological viewpoint, a performance composed of a low velocity and a great force is perceived to be more strenuous than a performance in which force is small and velocity high, even when the product of both factors remains constant. Relative to mechanical efficiency in cycling, the velocity of 40 to 60 crank revolutions per minute is optimal. Therefore, the frequency for which the cyclist searches is determined not by the most economic velocity but by the perception of tension." (p. 262)
There are some general features that concern rates of movements. Individuals who perform at higher rates tend to rely more on aerobic functions to energize performance. On the other hand, low-rating individuals seem to exploit anaerobic functions. Thus, the rate of turnover of cyclical movements will depend upon an athlete's performance capacities. An anaerobically endowed athlete will chose a lower rate while an aerobically endowed athlete will chose a higher rate. For example, runners with well-muscled legs will use a lower stride frequency (to exploit the greater leg strength that is associated with large muscle size) than will individuals with relatively thin legs that are muscled primarily with slow-twitch fibers. When both athletes run at the same speed, the rate of their foot strikes will differ. It is necessary for coaches to test the performance capacities of athletes to determine the relative strengths of these two capacities before suggesting changes in turnover rates of cyclical movements.
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