Dynamic Strength Index (DSI) is the ratio of an athlete's peak force in a ballistic test (typically the CMJ on a force plate) to their peak force in an isometric test (typically the IMTP). A DSI of 1.0 means the athlete can express the same force ballistically as they can isometrically; lower values mean the athlete has "strength reserve" they aren't expressing in fast actions.
Common interpretation: DSI < 0.6 suggests training emphasis should shift toward velocity and power development; DSI > 0.8 suggests the athlete needs more maximum-strength work to lift their ceiling.
Requires a force plate or load cell — DSI isn't measurable from field tests alone.
Where it's used
S&C program design at college, professional, and Olympic levels with force-plate access.
References
- Sheppard JM, Chapman D, Taylor K-L (2011). An evaluation of a strength qualities assessment method for the lower body. J Aust Strength Cond.
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