Correlating diurnal variations in peak athleticism with buccal gene expression in youth football players

Hourly variations in athletic performance are a well-documented physiological phenomenon in individual and team sports including football. Measuring the timing of maximal performance could potentially improve performance. Evidence suggests that buccal gene expression correlates with athletic performance, yet this has not been studied in sport-specific participants. Therefore, the study aimed to (A) examine the expression of Per2 and Bmal1 genes in 45 youth football players and correlate with countermovement jump (CMJ) performance; (B) investigate the fluctuations in Per2 and Bmal1 expression levels and CMJ performance at various timepoints during a regular training day. CMJ metrics (Reactive Strength Index-Modified, Force at Peak Power, Eccentric Duration, and Peak Power) and gene expression levels were measured in 45 youth football players at 08:30 and 17:30. Exercise timing made a significant difference in each measured performance metric at the individual and squad level. Thirty-four participants displayed increases in RSI-mod (p < 0.001) over the morning measurements. This contributed to an 8% increase in overall squad performance (p = 0.0009), which significantly correlated to buccal gene expression (R2 = 0.94). Profiling player buccal gene expression could inform the timing of training and rehabilitation protocols to coincide with maximal athletic performance in football, other team sports, and individual sports