Ventilatory Thresholds Differences According to Aerobic Fitness Level in 1450 Males and 241 Females on Cycle-Ergometer: A Cross-Sectional Study

The aim of the study was to analyze the influence of an aerobic fitness level on the percentage of maximum oxygen consumption, heart rate, and power output (%VO_2max, %HR_max, and %W_max) at which ventilatory thresholds 1 (VT1) and 2 (VT2) occur during a ramp incremental cycle-ergometer test in males and females considering age. 1450 males and 241 females performed a ramp incremental exercise test until exhaustion to determine VT1, VT2, and VO_2max. Combining the oxygen consumption at VT1, VT2, and VO_2max by clustering analysis, males were classified as a low, medium, or high aerobic fitness level and females were classified as a low or high aerobic fitness level. Results showed VO_2max was very poorly correlated with the %VO_2max at which VT1 and VT2 occur (r ≤ 0.115), whereas oxygen consumption at VT1 and VT2 showed a stronger positive association with the %VO_2max at which VT1 and VT2 occur, respectively (r = 0.357–0.604). Furthermore, the %VO_2max at which VT1 and VT2 occur were greater the higher the aerobic fitness level (all p ≤ 0.002), observing a high heterogeneity in the %VO_2max at which VT1 and VT2 occur even stratifying the sample by sex and aerobic fitness levels. In conclusion, the percentage of maximum at which VT1 and VT2 occur are better related to oxygen consumption at VT1 and VT2, respectively, than to VO_2max. Moreover, the common strategy consisting of establishing exercise intensity as a fixed percentage of maximum might not be effective to match intensity across individuals even if sex and aerobic fitness levels is considered.

Trial Registration

NCT06246760.