Examining the relationship between performance, recovery, and salivary biomarkers in NCAA DI American football athletes

Abstract

NCAA American football athletes undergo extensive training and performance demands. While inflammatory and hormonal biomarkers have been linked to performance and recovery in professional and elite athletes, this relationship remains less understood in collegiate athletes across a competitive season. This study examined athletic performance (PlayerLoad and countermovement jump (CMJ) metrics), recovery (self-report soreness and sleep quality), and salivary biomarker (interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), testosterone, cortisol, and testosterone-cortisol ratio (TC ratio)) relationships throughout a competitive season (14 weeks) in NCAA Division I American football athletes (n=39). Salivary samples were collected at pre-season (Week 0), mid-season (Week 7) and post-season (Week 15). Performance and recovery measures were collected each week from pre-season initiation to post-season. Athlete recovery metrics varied significantly depending on whether the athlete consistently held a position in the starting lineup (i.e., regularly started in games, t(15.70) = -2.62, p = 0.019) and was predicted by both inflammatory and hormonal biomarker concentrations, with further variance by position type. Reported soreness decreased significantly from pre-season to in-season (t(1195.60) = -4.66, p < 0.001) while sleep quality only varied significantly following a bye week. Performance metrics varied by starting status and position type as well. Inflammatory and hormonal biomarkers predicted performance through interactions with recovery status (t(20.392) = 29.906, p < 0.001) and season phase (t(33.876) = 3.637, p = 0.001). PlayerLoad varied significantly across pre-season and in-season, trending downwards as the competitive season continued and accumulated fatigue set in. Athlete peak power and force decreased significantly immediately following pre-season training (t(938.35) = -8.13, p < 0.001) indicating a lack of supercompensation. Reactive strength index-modified (RSImod) decreased for the first half of the season, but rebounded following a bye week, indicating its regulation based on fatigue. Inflammatory biomarkers (IL-6 and TNF-alpha) decreased significantly from pre-season to mid-season, demonstrating the high training demands of pre-season training, with disruption to the fatigue-recovery balance (t(64.49) = -2.47, p = 0.042 and t(65.258) = 2.79, p = 0.019). At the onset of within-week tapering, inflammation dropped due to increased opportunities for recovery. Hormonal biomarkers (cortisol, testosterone, and TC ratio) did not vary significantly across season phases. These findings illustrate the dynamic interplay between recovery and performance metrics over the course of a season. The study underscores the significance of individual factors in interpreting athlete data, and emphasizes the value of integrating recovery measures, external load, force, power, and biomarker assessments to gain a comprehensive understanding of athlete performance.