방법 비교

	Electromechanical Delay	반응 강도 지수
분야	스포츠과학	스포츠과학
계열	Hypothesis test	Hypothesis test
기원 연도	1979	1987
창시자	Paavo Komi	Marteen Bobbert
유형	EMG-force analysis	elastic response test
원전	Cavanagh, P. R., & Komi, P. V. (1979). Electromechanical delay in skeletal muscle under normal movement conditions. Acta Physiologica Scandinavica, 106(3), 241-248.	Bobbert, M. F., Huijing, P. A., & van Ingen Schenau, G. J. (1987). Drop jumping. II. The influence of dropping height on the biomechanics of takeoff after landing. Medicine & Science in Sports & Exercise, 19(4), 339-346.
별칭	EMD, electromechanical lag, neural delay, activation delay	RSI, stretch-shortening cycle, elastic response
관련	5	3
요약	Electromechanical delay (EMD) is the time interval between electrical muscle activation (detected via electromyography) and the first detectable mechanical force output. Introduced by Cavanagh and Komi (1979), EMD reflects the physiological lag inherent in converting neural input into mechanical work. This delay arises from several sources: time for the action potential to propagate, time for calcium release, time for cross-bridge cycling to begin, and elastic recoil of muscle-tendon structures. EMD is typically 30-100 milliseconds in skeletal muscle and varies with muscle group, contraction type, and training status. Understanding EMD is important for explaining performance in rapid movements and for assessing neuromuscular function.	The reactive strength index (RSI) is a measure of lower-body reactive strength and elastic energy utilization, calculated as jump height divided by the contact time between landing from a drop and takeoff. Introduced by Bobbert and colleagues (1987), RSI quantifies the efficiency of the stretch-shortening cycle (SSC)—the ability to rapidly switch from eccentric (lengthening) to concentric (shortening) muscle contractions. High RSI indicates rapid, forceful engagement of muscles' elastic properties (tendons, contractile proteins) and is relevant in sports requiring rapid rebound (sprinting, jumping, rebounding). RSI is trainable and sensitive to plyometric training.