Estimating Maximal Aerobic Speed in Academy Soccer Players: A Comparison Between Time Trial Methods and the 30-15 Intermittent Fitness Test

Aerobic fitness is crucial to team sport performance and can be estimated practicallythrough field-based assessments of Maximal Aerobic Speed (MAS) in soccer players.However, method comparisons are under-explored. This study compared MASestimation via a 6-minute distance trial (6minDT), 1800-m time trial (1800mTT), and the30-15 Intermittent Fitness Test (30-15IFT) and qualitative preferences in academy soccerplayers. Twenty-six male players (age: 17.2 ± 0.6 years; stature: 178.4 ± 5.1 cm; bodymass: 71.8 ± 7.7 kg) completed a 30-15IFT, 6minDT, and 1800mTT in a counterbalancedorder. Total distance was measured via 10 Hz Global Positioning System units, with 30-15IFT MAS defined as 87% of finishing speed (vIFT), and 6minDT and 1800mTT MASdetermined as distance divided by time to completion. Pearson’s correlationscalculated associations between MAS estimates, and a robust repeated measuresANOVA estimated marginal mean differences between tests. A very large associationwas observed between performance in the 1800mTT and 6minDT (r = 0.72; 95%confidence interval, 0.46 to 0.86). Large associations were observed between the 30-15IFT and 6minDT and 1800mTT (6minDT: r = 0.65; 0.35 to 0.83; 1800mTT: 0.66, 0.37 to0.84), respectively. MAS estimated from the 30-15IFT was significantly higher than the6minDT (0.57, 0.50 to 0.65 m·s-1, p<0.0001) and 1800mTT (0.45, 0.37 to 0.52 m·s-1, p<0.0001). MAS estimated from the 6minDT was lower than the 1800mTT (-0.13, -0.21 to -0.05 m·s-1, p = 0.0002). In conclusion, while associations between 6minDT, 1800mTT,and 30-15IFT derived MAS exist, all tests provide distinct estimations of MAS.