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SUMMARY
EFFICIENT STRETCH-SHORTENING CYCLE (SSC) MECHANICS RESULT IN ENERGY CONSERVATION AND ENHANCED PROPULSIVE FORCES. BASED ON THE CURRENT REVIEW OF RESEARCH, ELASTIC ENERGY THROUGH TENDON RECOIL AND AN INCREASE IN ACTIVE STATE BECAUSE OF AN INCREASE IN THE WORKING RANGE SEEM THE MOST PLAUSIBLE EXPLANATION FOR THE SSC MECHANISM. USING THE RESEARCH PRESENTED, THE SSC MECHANISM MAY BE BEST DEVELOPED USING THE PLYOMETRICS PYRAMID ENSURING THAT THE ATHLETE IS TECHNICALLY COMPETENT AT EACH STAGE BEFORE PROGRESSING IN INTENSITY AND COMPLEXITY. STRENGTH TRAINING AND SSC TRAINING SHOULD BE PERFORMED CONCURRENTLY. SSC DRILLS SHOULD BE BASED ON STRENGTH CAPACITIES AND SPORT-SPECIFIC VARIABLES.
KEY WORDS:
stretch-shortening cycle; elastic energy; tendon; stiffness; spindle; Golgi tendon organ
INTRODUCTION
It is well established that a vertical jump preceded by a countermovement (i.e., a prestretch) will increase vertical displacement above a squat jump (one with no prestretch) (10). Investigations have revealed improvements in the range of 18-20% (15) to 20-30% (13) and a difference in maximum jump height of approximately 2-4 cm (9). Moreover, by increasing the load applied and the rate of loading during the countermovement, for example, after a run-up or a depth jump, jump height may further increase (4,8,77,78). This phenomenon is a consequence of what is termed the stretchshortening cycle (SSC), which describes an eccentric phase or stretch followed by an isometric transitional period (amortization phase), leading into an explosive concentric action. The SSC is synonymous with plyometrics (37) and is often referred to as the reversible action of muscles (112). Other examples of SSC actions include the natural parts of movements such as running or walking or the wind up movement in throwing.
Aside from an enhanced concentric contraction (propulsive force), efficient usage of the SSC also affords the athlete with a reduction in the metabolic cost of movement (9,10). This may be evidenced with data suggesting that the energetic cost of running for animals with heavy limbs is about the same as those with light limbs (as heavier limbs would increase the load applied and the rate of loading) (40). In addition, Verkhoshansky (101) and Voigt et al. (102) reported that economical sprinting (i.e., efficient usage of the SSC) can recover approximately 60% of the total mechanical energy (40% being replenished by metabolic processes...