Understanding the Fatigue-Recovery Cycle in Team Sport Athletes

Abstract

Identifying and understanding the fatigue response of athletes following intensive training and competition is necessary to avoid injury, performance decrements and overtraining. There is an abundance of tests and monitoring tools that have been used to describe the fatigue response of both individual-and team-sport athletes. These tests typically include measures of neuromuscular function, subjective questionnaires, blood and salivary markers, or physical performance tests. Importantly though, the tests employed must be valid, reliable and practically convenient in applied settings. Investigators have commonly assessed fatigue measures during tournament competition [1-3] or over subsequent days following competitive matches [4-6] in an attempt to identify the time course of the fatigue-recovery cycle. This provides an understanding of how an athlete recovers from competition and guides training loads and recovery practices when athletes may be most vulnerable to non-functional overreaching and injury. Measures of neuromuscular function have commonly been used to examine the fatigue response following team sport activities and have been suggested to be reliable indicators of low-frequency fatigue [7,8]. Neuromuscular function has been assessed using jumping protocols, sprinting performance, and isokinetic and isointertial dynamometry. Perhaps the most commonly utilised are jumping tests, as they incorporate the stretch-shortening capability of the lower body musculature and are easy to administer. Measures of both upper-and lower-body neuromuscular function such as mean power and force production, time to peak force and jump height and have shown acceptable reliability and day-to-day variability making them useful measures to assess fatigue over a training mesocycle or playing season [9-11]. Team sport athletes competing in contact sports such as rugby football can show severe reductions in both upper-and lower-body neuromuscular function following match-play suggested to be caused by reductions in contraction velocity associated with increased muscle damage [12-14]. Other studies examining neuromuscular fatigue in low or non-contact team sports have questioned the sensitivity of jumping-derived measures [1,15]. However, the degree of jump performance decrement has been associated with match activities such as maximal decelerations that likely cause exercise-induced muscle damage and increases in general muscle soreness in these sports [1]. Further, decreased jump performance has been associated with reduced physical and technical performance during subsequent match-play suggesting that jump-derived measures provide a valid assessment of neuromuscular fatigue for team sport athletes [1,16,17]. Subjective questionnaires are another simple and cost-effective tool to assess the fatigue-recovery cycle following competition and training activities. There are a number of questionnaires that have been used in the literature such as the POMS, RESTQ-Sport and DALDA questionnaires [8,18]. Studies have shown alterations in perceptual