Sprint speed sells. Athletes ask for it, parents pay for it, and every combine measures it. The countermovement jump is the fastest way to find out whether an athlete has the explosive power that speed requires.
A jump predicts a sprint
Jumping and sprinting draw on the same qualities: force production, rate of force development, and coordination. Research by Loturco and colleagues found a strong correlation between CMJ height and sprint times. An athlete who jumps high produces force fast, and that same quality drives acceleration and top speed. The movement itself mirrors sprinting, too. The athlete dips at the knees and hips, then pushes off hard, the same pattern as each stride's drive phase.
What the jump tells you that a stopwatch can't
A 40-yard time tells you an athlete is slow. It doesn't tell you why. CMJ testing isolates the cause:
- Deficits in force production or rate of force development
- Neuromuscular fatigue, before it shows up as a bad session
- Whether power training is transferring to sprint performance
Test monthly and you get a trendline instead of a guess.
Measuring it without force plates
Force plates cost thousands and live in labs. Demotu measures jump height, landing mechanics, and movement efficiency from a phone camera, then flags the weaknesses holding sprint speed back so you can pick corrective work from data.
Track the jump, train the deficits it exposes with explosive strength work and plyometrics, and retest. Sprint mechanics improve because the engine behind them got stronger.