Convergent Validity of the Flight Time and Impulse-Momentum Methods of Calculating Countermovement Jump Height

Abstract

The countermovement jump test is considered to be one of the best assessments of lower body power in athletic populations. Impairments in jump height have been previously shown to be indicative of acute and chronic exercise-induced fatigue. There are a number of different methods to calculate vertical jump height utilizing a force platform including the flight time and impulse-momentum methods. However, there has been limited research comparing vertical jump heights derived from either method in elite-level athletes. PURPOSE: To examine the convergent validity between flight time and impulse-momentum methods of calculating countermovement jump height in elite male soccer players. METHODS: Thirty-four collegiate Division-1 men’s soccer players (age 20.4 ± 1.5 years; height 181.7 ± 6.1 cm; body mass, 80.2 ± 8.1 kg) were assessed for vertical jump height using a force plate (Bertec AM 651x Force Plate, Bertec Corporation, Columbus, OH). Each subject completed three attempts of the countermovement jump test with 1-min rest intervals. RESULTS: No significant bias was detected between methods (mean, 0.25 cm; 95% CI, -0.11 to 0.61 cm; p > 0.05). Furthermore, there was a very strong correlation observed between methods (r = 0.93; p < 0.01). CONCLUSION: The flight time and impulse-momentum methods possess convergent validity and each provide an accurate measurement of vertical jump height in elite-level athletes. However, the flight time method may be more preferable for practical applications due to its relative simplicity.