Construct validity of a new intermittent aerobic fitness field test in elite soccer players

Background: The aim of the study was to evaluate the construct validity of a novel constant-velocity Intermittent Recovery Test (IRT), designed to evaluate aerobic fitness in the field in soccer players. Methods: Eighteen elite soccer players (age: 24.0±7.2 years, body mass: 82.9±6.8 kg, height: 184.7±5.2 cm) completed the IRT test, consisting of 50-m runs at 18 km/h (10-s/50 m), interspersed by a recovery time initially set at 17 s, gradually decreased up to 2 s, and then held constant until exhaustion. The maximum oxygen uptake (VO2max) measured by means of a portable gas analyzer, and the distance covered during the test were recorded, and their relationships with a selection of physical performance indicators collected during official matches were assessed with Pearson's r correlation coefficients. Results: Small to moderate (r≤0.45), non-significant correlations (all P>0.05) were observed between VO2max and all the examined match performance variables. Conversely, the distance covered at exhaustion was largely and positively correlated (r=0.71 to 0.76) to total distance covered, average metabolic power, distance covered at high metabolic power, and acceleration/deceleration distance (all P<0.01). Conclusions: The present findings reveal good construct validity of the distance covered in the IRT to predict match physical performance in elite soccer players.