What it measures
Reactive Strength Index (RSI = jump height ÷ ground contact time). Indexes how efficiently an athlete converts a high-velocity eccentric pre-load into concentric output. Highly relevant for sprinters and field-sport cutting.
Equipment
- Plyo box (30, 40, or 50 cm) — most labs default to 40 cm
- Contact mat or force plate for ground-contact-time measurement
- Optional: high-speed camera (120+ fps) as backup
Protocol
- Athlete stands on the box, hands on hips.
- Athlete steps off (does not jump up off) the box, dropping straight down.
- On contact with the ground, immediately rebound as high as possible — minimize ground contact time.
- Coach reminds athlete: 'jump as high as you can, on the ground as briefly as possible.'
- 60 s between trials. Best of 3 successful attempts.
Scoring
RSI = jump height (m) ÷ ground contact time (s). Higher is better. Performance House also stores raw jump height and ground-contact-time separately.
Typical ranges
Elite sprinters: RSI 3.0–4.0. NCAA male field sport: 2.0–3.0. Untrained adults: 0.8–1.5.
Practical notes
- Box height matters — go with 40 cm as the default; higher boxes test different physiological qualities and complicate cross-athlete comparison.
References
- Schmidtbleicher D (1992). Training for power events. In: Strength and Power in Sport (Komi, ed.).
Use this test in Performance House
Performance House supports Drop Jump as a built-in test metric — log results from any device, see longitudinal trends, and contribute the result to the athlete's Performance Index automatically. Free for up to 5 athletes on the Starter plan.
Browse the full protocol library for related tests, or jump to one of the related protocols below.