Countermovement Jump To Monitor Neuromuscular Fatigue In Endurance Athletes : A correlation study between training load and CMJ-variables

Abstract: Training load monitoring is crucial to examine fatigue status. The currently available methodsshow diverse validity, and each come with their limitations. The advantages of CMJ are manyand seem to be useful within team sports, although its use on endurance athletes needs moreresearch. Using force plates is agreed to be the best method, but the uncertainty of whichvariables to use when monitoring fatigue creates difficulties, yet currently, no optimal methodis identified. The purpose of this study was to investigate the use of CMJ and its variables onendurance athletes. Ten triathletes participated in the study, performing the CMJ two times aweek for five weeks. The training load from each session was quantified using Lucia’sTRIMP. A correlation analysis between total TRIMP three days prior to testing and eightdifferent CMJ-variables were made; jump height-flight time (JH-FT), jump height-impulse(JH-IM), Reactive Strength Index-flight time (RSI-FT), Reactive Strength Index-impulse(RSI-IM), braking duration (B-DUR), braking impulse (B-IM), propulsive duration (P-DUR),propulsive impulse (P-IM). A small positive correlation was found between TRIMP and JHFT (r =0.23), JH-IM (r = 0.24), RSI-FT (r = 0.13), and RSI-IM (r = 0.13). B-DUR and B-IMhad a small negative correlation (r = -0.10, r = -0.11) while P-DUR and P-IM showed nocorrelation (r = < 0.02). No significance was found in any correlations (p > 0.05). Resultsindicated that JH may provide better information about fatigue compared to other variables.Variables from the braking phase seem more sensitive to training load compared to thepropulsive phase. Using flight time seems to provide similar results as impulse which couldsimplify fatigue monitoring. However, due to limitations of the study the results should beviewed with caution and more research is needed for further conclusions.Keywords; Jump height, Reactive Strength Index, Flight time, impulse