Equivalence Between Land and Water Countermovement Jump for Physical Performance Testing

Background and Purpose: Vertical jumps are widely used to assess physical performance and power. The authors believe that the countermovement jump (CMJ) test can be used as an assessment tool for healing athletes who are able to tolerate the within water impact but who cannot tolerate this test on land. To explore this, the first step is to determine whether vertical jump performance in water is equivalent to that on land. Methods: Healthy volunteers (n = 79; 28 women, 51 men; 29.58 ± 10.6 years) performed 3 valid repetitions of the CMJ on land and in water, with free motion of the upper limbs. The highest jump height from the 3 attempts in each environment was selected for analysis. Results: The average jump height in water (41.39 ± 9.94 cm) was significantly higher than on land (34.30 ± 12.76 cm). An adjusted water score was computed to facilitate equivalence analysis. The comparison of land versus adjusted water score demonstrate moderately high concordance correlation coefficient (0.80; 95% CI: 0.71-0.86) and significant equivalence ( P < .001). Discussion: Our findings indicate that the in-water CMJ exhibits strong concordance and equivalence with the on-land CMJ, supporting its validity as a tool for physical performance assessment. Conclusions: Given the unique properties of the aquatic environment, the in-water CMJ test could be a suitable alternative for evaluating physical function for recovering athletes who can tolerate this test.