Indirect Estimation of VO2 Max in Athletes by ACSM’s Equation: Valid or Not?


The purpose of this study was to assess the indirect calculation of VO2max using ACSM’s equation for Bruce protocol in athletes of different sports and to compare with the directly measured; secondly to develop regression models predicting VO2 max in athletes.


Fifty five male athletes of national and international level (mean age 28.3 ± 5.6 yrs) performed graded exercise test with direct measurement of VO2 through ergospirometric device. Moreover, 3 equations were used for the indirect calculation of VO2max: a) VO2max = (0.2 · Speed) + (0.9 · Speed · Grade) + 3.5 (ACSM running equation), b) regression analysis model using enter method and c) stepwise method based on the measured data of VO2. Age, BMI, speed, grade and exercise time were used as independent variables.


Regression analysis using enter method yielded the equation (R=.64, standard error of estimation [SEE] =6.11): VO2max (ml·kg-1·min-1) = 58.443 – (0.215 · age) – (0.632 · BMI) – (68.639 · grade) + (1.579 · time) while stepwise method (R = .61, SEE = 6.18) led to: VO2max (ml·kg-1·min-1) = 33.971 – (0.291 · age) + (1.481 · time). The calculated values of VO2max from these regression models did not differ significantly from the measured VO2max (p>.05). On the contrary, VO2max calculated from the ACSM’s running equation was significantly higher from the actually measured value by 14.6% (p <.05).


Our results indicated that the widely used ACSM’s running equation performing the Bruce protocol in many sport centers is not accurately predicting VO2max in athletes aged 18 – 37 years. Thus, it is verified that direct measurement of VO2max in athletes should be preferred instead. Cardiopulmonary exercise testing is the only way to directly measure VO2, but despite this, the estimation of exercise capacity based on equations will undoubtedly continue mainly due to cost effectiveness issues. In case of indirect estimation of maximal aerobic capacity, regression models in specific populations of different age and physical fitness with standard treadmill velocities and grades would be most efficient in predicting VO2max. Further studies are encouraged to develop and examine precise regression models that accurately estimate VO2max.

Koutlianos N, Dimitros E, Metaxas T, Deligiannis AS, Kouidi E.  HIPPOKRATIA 2013, 17, 2:136-140.

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