Comparison of VO₂max Estimations for Maximal and Submaximal Exercise Tests in Apparently Healthy Adults

Due to limited accessibility, direct measurement of VO₂max is rarely performed in clinical settings or sports centers. As a result, regression equations have been developed and are currently used during exercise tests to provide an indirect estimation. The American College of Sports Medicine (ACSM) has recommended a regression equation for running to provide an indirect estimation of VO₂. However, significant differences have been observed between these estimations and directly measured VO₂max. Additionally, since submaximal assessments may be more convenient for both athletes and sedentary/diseased individuals, they were included in the analysis. This study aimed to evaluate the accuracy of VO₂max estimations provided using the ACSM running equation when used during both maximal and submaximal exercise tests among adult runners. A total of 99 apparently healthy and active adults (age: 39.9 ± 12.2 years; VO₂max: 47.4 ± 6.0 mL O₂/kg∙min^-1) participated in this study. Two types of submaximal estimations were performed to predict VO₂max: one based on age-predicted maximal heart rate (HRmax) (ACSM_submax,Fox), and the second using the actual HRmax measured during the exercise test (ACSM_{submax,measured}). The measured VO₂max was compared to these estimations obtained from a single exercise test. Both maximal and submaximal exercise tests significantly overestimated VO₂max (ACSM_max: +9.8, p < 0.001; ACSM_submax,Fox: +3.4, p < 0.001; ACSM_{submax,measured}: +3.8 mL O₂/kg∙min^-1, p < 0.001). However, the submaximal estimations were closer to the measured VO₂max (p < 0.001). This analysis demonstrated that the included methods overestimated the true VO₂max. Nonetheless, the submaximal exercise tests provided a more accurate prediction of VO₂max compared to the maximal exercise tests when using the ACSM running equation.