Year of Publication


Date of Thesis


Document Type


Degree Name

Master of Science


Exercise and Sport Sciences


Background: Testing is used by coaches to evaluate and identify program direction, identify player potential and to monitor fatigue. The countermovement jump (CMJ) test is commonly used to measure and monitor athletes’ power production. To interpret change, coaches need to establish the expected level of variability in athlete tests performance. Research indicates different populations exhibit different levels of variability in test scores. Thus, coaches must understand the variability of the team / athletes being tested before drawing conclusions from test results. Objective: The purpose of this study was to measure the reliability of CMJ performance in collegiate athletes with and without the use of an arm swing. Methods: Eight athletes (5 female and 3 male) of Ithaca College’s varsity athletics program completed six CMJs (3 allowing arm swing and 3 without arm swing) on two separate days. Jumps were recorded on participant’s personal cellular phone and uploaded online for the research team to analyze. Movement time (MT) and flight time (FT) were measured with the mobile application My Jump 2 (XCode 5.0.5 for Mac OSX 10.9.2; Apple, Inc., USA). Jump height (JH) and the modified reactive strength index (RSImod) were calculated from MT and FT. Statistical Analysis: A 2-by-2 repeated measures analysis of variance was completed to examine differences in jump variables between jump conditions and between days. Intraclass correlation coefficients (ICC), 95% confidence intervals of the ICC and coefficients of variation were used to identify reliability between the two test days for MT, FT, JH, and RSImod. Results: Data showed FT to be significantly larger in the countermovement jump with an arm swing relative to the countermovement jump without an arm swing condition. Examination of reliability indices showed weak reliability for MT, FT, and JH in the countermovement jump without an arm swing condition. MT, FT, and JH exhibited poor reliability in the countermovement jump with and arm swing condition. RSImod exhibited poor reliability under both jump conditions. Conclusion: The results suggest that FT is the only variable to produce a statistically significant difference when completing the two jump conditions. Based on the current study’s results, the My Jump 2 phone application does not appear to be a reliable device to measure variables of CMJ performance for athletes remotely.



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