Objective The purpose of this study was to determine if peak power output (PPO) adjusted for body mass^0.32 is able to accurately predict 40-km time trial (40-km TT) performance.

Methods 45 trained male cyclists completed after familiarisation, a PPO test including respiratory gas analysis, and a 40-km TT. PPO, maximal oxygen consumption (VO_2max) and 40-km TT time were measured. Relationships between 40-km TT performance and (I) absolute PPO (W) and VO_2max (l/min), (II) relative PPO (W/kg) and VO_2max (ml/min/kg) and (III) PPO and VO_2max adjusted for body mass (W/kg^0.32 and ml/min/kg^0.32, respectively) were studied.

Results The continuous ramp protocol resulted in a similar relationship between PPO and VO_2max (r=0.96, p<0.0001) compared with a stepwise testing protocol but was associated with a lower standard error of the estimated when predicting VO_2max. PPO adjusted for body mass (W/kg^0.32) had the strongest relationship with 40-km TT performance (s) (r=−0.96, p<0.0001). Although significant relationships were also found between absolute (W) and/or relative PPO (W/kg) and 40-km TT performance (s), these relationships were significantly weaker than the relationship between 40-km TT performance and PPO adjusted for body mass (W/kg^0.32) (p<0.0001).

Conclusions VO_2max can be accurately predicted from PPO when using a continuous ramp protocol, possibly even more accurately than when using a stepwise testing protocol. 40-km TT performance (s) in trained cyclists can be predicted most accurately by PPO adjusted for body mass (W/kg^0.32). As both VO_2max and 40-km TT performance can be accurately predicted from a PPO test, this suggests that (well)-trained cyclists can possibly be monitored more frequently and with fewer tests.