השוואת שיטות

	מדד החוזק הריאקטיבי	פרופיל כוח-מהירות
תחום	מדעי הספורט	מדעי הספורט
משפחה	Hypothesis test	Hypothesis test
שנת המקור	1987	2007
הוגה השיטה	Marteen Bobbert	Biomechanics Research Group
סוג	elastic response test	mechanical profiling
מקור מכונן	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.	Bampouras, T. M., Comyns, T. M., Daly, D. J., & Deighan, M. A. (2007). Comparison of the Wingate test and an isokinetic anaerobic test in recreationally active children. British Journal of Sports Medicine, 41(12), 822-825.
כינויים	RSI, stretch-shortening cycle, elastic response	FVP, force-velocity curve, power profile, strength-speed balance
קשורות	3	5
תקציר	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.	The force-velocity profile characterizes an individual's mechanical properties across the force-velocity spectrum, revealing whether strength advantage lies in maximal force production or high-velocity power output. Formalized by Samozino and colleagues (2012), the FVP is derived from multiple load-velocity measurements (typically sprint starts, jumps, or push-off movements at various resistances) and mathematically modeled as a linear inverse relationship between force and velocity, anchored by maximal power. Athletes differ markedly in their FVP: some excel at moving heavy loads slowly (force-dominant), while others excel at moving light loads fast (velocity-dominant). Profiling identifies these phenotypes and informs targeted training interventions.