How Much Can a Few Coaching Words Change a Drop Jump?

Imagine being asked to judge two drop jumps. In one, the athlete seems to leave the floor almost immediately; in the other, the rebound looks higher. Which would you choose? You might want to know what the athlete was trying to do before you decide. 'Make it better' sounds like a clear instruction, but it leaves an important question open: what, exactly, is supposed to improve?

In a drop jump, the athlete steps off a platform, lands, and immediately jumps upward. Twenty male collegiate athletes familiar with the movement tested four instructions from a 30-centimeter platform, barefoot, with hands on hips and minimal knee bend. Shorter ground contact favored the two quick-rebound instructions. One emphasized minimizing time on the floor. Another asked them to imagine hot ground and leave quickly. Compared with an instruction to get close to the ceiling, both produced shorter contact times, the interval from landing to takeoff. Mean times were 0.181 and 0.179 seconds for the quick-contact instructions, versus 0.193 seconds for the ceiling instruction.¹

Greater rebound height favored the ceiling instruction in those same comparisons. Estimated height averaged 0.332 meters, compared with 0.313 and 0.312 meters under the two quick-contact instructions. Height was inferred from flight time rather than measured directly as vertical displacement. The paired results describe particular cue comparisons in this small sample: they do not establish that every instruction aimed at height must lengthen contact, or that every athlete faces an inevitable trade-off.¹

The reactive strength index, or RSI, combines the two measurements by dividing estimated jump height in meters by contact time in seconds. The fourth instruction also emphasized height, using the image of a spring reaching toward a roof. Across all four conditions, mean RSI values ranged from 1.74 to 1.77 meters per second, and the analysis detected no statistically significant condition difference. That ratio result does not erase the differences in its components. No equivalence test was performed, so the nonsignificant result does not establish equal performance. These were acute test performances, not a training intervention or a comprehensive assessment of reactive-strength capacity.^1,2

An assessment is more useful when 'better' has a clear meaning. For a drop jump, that means stating the goal and reading the score alongside the measurements used to calculate it. The conclusion can then stay with the performance being judged. It does not need to become a verdict on the athlete's overall ability, or a prediction about what future training will achieve.