‘Temporary fatigue’ is not apparent in elite youth soccer players
However, the use of velocity bands to characterise ‘temporary fatigue’ is a technique that might be insensitive to some high-intensity activities, which may cause transient fatigue through neuromuscular or metabolic pathways. Highintensity actions such as collisions, accelerations, decelerations, unorthodox running and turns often occur at velocities below 15 km·h-1, but these activities are metabolically taxing (Osgnach et al., 2010; Reilly and Bowen, 1984). The advancement of micro-sensor technology now enables practitioners in team sports settings to measure the frequency and magnitude of instantaneous accelerations in the anterior-posterior, medio-lateral, and longitudinal planes. The tri-axial accelerometer is typically used for estimates of physical activity and energy expenditure, therefore powerful movements and accelerations, which are absent from traditional time-motion techniques, can now be quantified during match-play in field-based settings. We postulated that the use of tri-axial accelerometer data might be a more sensitive tool to detect ‘temporary fatigue’.