Changes in Body Mass and Movement Strategy Maintain Jump Height Immediately after Soccer Match

A countermovement jump (CMJ) performed on a force plate is commonly applied in soccer to quantify acute neuromuscular fatigue (NMF), which may manifest immediately following soccer match play. Jump height (JH) is the main outcome variable reported for this purpose; however, it is sensitive to alterations in movement strategy, which may act to mask JH and, therefore, mask any presence of NMF. Acute reductions in body mass (BM) during match play could also lead to the maintenance of JH, but this is yet to be explored. This study sought to explore soccer-match-induced alterations to JH, movement strategy, and BM to inform future variable selection for the study of acute NMF. Fourteen male English National League soccer players performed three CMJs on a dual-force plate system immediately before and after a competitive soccer match. Differences in jump height were non-significant and trivial (p = 0.924, g = 0.03) before and after soccer match play, but there was a large post-match decrease in BM (g = 1.66). Furthermore, moderate decreases in jump momentum (g = 0.56) and countermovement depth (g = 0.72) were noted. As JH was determined by the take-off velocity, reduced BM could have augmented it (less mass to accelerate); however, reduced countermovement depth seemingly counteracted this (less distance to attain velocity). It may, therefore, be beneficial to report these variables when monitoring acute NMF via the CMJ.