This chapter describes the fatigue response after games and throughout the season identifies player's recovery and helps determine appropriate training loads to maximise performance. Heart rate variability (HRV) can be used to assess the health and training status of athletes and have been used within elite youth rugby players to report lower cardiac autonomic response, the practical limitations associated with HRV perhaps detract from its appeal as a suitable measurement tool to assess fatigue status in rugby players. Neuromuscular function in rugby players can also been assessed using isometric and isokinetic dynamometry. The combination of measured changes in neuromuscular function or performance can be employed with perceptual data to determine the fatigue status of a rugby player. A change of this magnitude, in addition to a meaningful change in neuromuscular function or performance, can be considered to be indicative of fatigue and required the initiation of rest or a given recovery strategy until measures return to values close to baseline.