VALIDITY AND RELIABILITY OF COUNTERMOVEMENT VERTICAL JUMP MEASURING DEVICES

D. Steinman, M. Shirley, M. Fuller, C. Reyes Linfield College, McMinnville, OR The countermovement jump (CMJ) test is a standard measure of lower body power. The jump performance in the test can be related to other aspects of athletic performance. With many tools commercially available, it can be difficult for professionals to distinguish which device provides the most accurate results for the best cost. While these devices have been previously validated individually, no past studies have concurrently examined these specific tools. PURPOSE: The purpose of this study was to determine the accuracy of four different CMJ measuring devices when compared to the gold standard of a force plate. METHODS: 31 physically-active university students were recruited for this study (21 ± 3.3 years; 176 ± 10 cm; 80 ± 17 kg; 9 females, 21 males). The participants were lead through a standardized 10-minute warm-up protocol consisting of dynamic stretching and concluding with instruction of proper jumping technique for the tests. Participants then performed 4 maximal CMJ on the force plate, which served as the gold standard for CMJ measures. Following the gold standard jumps, all participants performed an additional 4 maximal CMJ in an area where 4 other instruments were used to measure CMJ simultaneously: accelerometer-based sensor, a contact mat, a photoelectrical cell system, and a mobile device video app. The researchers measured each CMJ synchronically. A data analysis was conducted using IBM SPSS Statistics and Microsoft Excel. An analysis of variance (ANOVA) and intra-class correlation (ICC) were used to analyze the differences between devices. RESULTS: The ANOVA revealed a significant difference in mean CMJ performance between the force plate and the photoelectrical cell system and the mobile device video app (p\u3c 0.001). All devices displayed a strong correlation to the force plate with the contact mat displaying the highest ICC (r = 0.899). CONCLUSION: All four commercial devices showed strong within-device reliability and strong relationships to the force plate regarding CMJ performance. But, only the contact mat and accelerometer-based sensor measured CMJ performance closest in score to the force plate. In summary, while slightly over-estimating measurements, the commercial devices that seem to agree the closest to the gold standard force plate were the contact mat and accelerometer-based sensor