Assessing the Validity of Two Non-Exercise Regression Equations for Predicting Maximal Oxygen Consumption

ABSTRACT

Purpose: This study aimed to develop two regression equations to predict maximal oxygen consumption (VO_2max) using non-exercise data from a substantial cohort of healthy Iranian adult males. Additionally, this study sought to examine the predictive accuracy of these equations across four different levels of physical activity. Methods: A total of 126 participants (age: 34.9 ± 11.3 years, body mass index [BMI]: 24.9 ± 2.7 kg/m², and body fat percentage [BF%]: 18.3 ± 4.9) completed a maximal graded exercise test to measure VO_2max, with a mean of 45.0 ± 3.4 ml.kg⁻¹.min⁻¹. Participants also provided information on age, current physical activity rating (PA-R), and either BMI or BF% to estimate VO_2max using Jackson and colleagues’ regression equations. The PA-R was assessed via a standardized questionnaire and categorized into four levels: sedentary, low, moderate, and high. Results: The key findings from this study indicate that both original models significantly underestimated actual VO_2max in a large cohort of Iranian adults (both, p < .001 and mean differences exceeding 2.19 ml.kg⁻¹.min⁻¹). Nevertheless, these models provided accurate predictions for VO_2max among individuals with moderate levels of physical activity (both, p > .08 and mean differences between 0.51 and 1.03 ml.kg⁻¹.min⁻¹). Furthermore, the models demonstrated moderate validity, as evidenced by an intraclass correlation coefficient (ICC) of 0.841 and a coefficient of variation averaging 10.9%, with a range from 8.5% to 13.6%. Conclusions: While Jackson’s two non-exercise models showed limited accuracy in predicting VO_2max among Iranian healthy male adults, they exhibited reasonable precision, particularly among moderately active men.

KEYWORDS:

• Non-exercise model
• physical Activity
• questionnaire
• validation
• VO_2max

Acknowledgments

The authors would like to thank our enthusiastic participants.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authorship contributions

All authors met the criteria for full authorship. Mahmoud Nikseresht: Methodology, Validation, Formal Analysis, Investigation, Writing—Original Draft, Writing—Review & Editing, Project Administration. Carlo Castagna and Mehdi Nikseresht: Validation, Investigation, Writing—Review & Editing.

Availability of data and material

Data and material are available on reasonable request to the corresponding author.

Cover letter

The authors confirm the above work is original research, has not been previously published, and has not been submitted for publication elsewhere while under consideration.

Ethical approval

This study was approved by the Research Ethics Committee of the Faculty of Exercise Physiology at the Islamic Azad University, Ilam Branch. All subjects gave written informed consent.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.