The reliability and validity of the Astrand nomogram and linear extrapolation for deriving VO2max from submaximal...

Area of Science:

• Exercise Physiology
• Cardiorespiratory Fitness Assessment

Background:

• VO2max testing is the gold standard for aerobic power but is highly demanding and poses practical/ethical challenges for non-athletic and patient populations.
• Existing alternative methods like the Astrand-Ryhming nomogram and linear extrapolation have limitations in equipment and sample size.
• A need exists for a reliable and accessible method to measure aerobic power in diverse populations.

Purpose of the Study:

• To evaluate the accuracy and reliability of linear extrapolation of submaximal heart rate/oxygen uptake data compared to VO2max.
• To assess the Astrand-Ryhming nomogram as a predictive tool for aerobic power.
• To determine a practical alternative for aerobic power assessment in non-athletic and clinical settings.

Main Methods:

• Twenty-five healthy subjects completed 52 trials using the Bruce treadmill protocol under stringent VO2max criteria.
• Respiratory gases were measured using a portable gas analyzer with a five-second sample period.
• Data analysis focused on comparing the reliability and validity of linear extrapolations (to three heart rate maximum estimates) against the Astrand nomogram prediction.

Main Results:

• Linear extrapolation demonstrated high reliability, with an intraclass correlation coefficient (ICC) of 0.9433, comparable to observed VO2max (0.9443).
• The extrapolation method showed a minimal bias of -1.1 ml x min(-1) x kg(-1), indicating a 2.19% underestimate of aerobic power.
• Extrapolation proved preferable to the Astrand-Ryhming nomogram in this study.

Conclusions:

• Submaximal data extrapolation is a reliable method for aerobic power assessment, suitable for clinical monitoring and research.
• The use of portable equipment and submaximal testing expands research possibilities in various populations and non-laboratory settings.
• This study provides empirical support for using linear extrapolation as a valid alternative to VO2max testing.