Accurate quantification of exercise volume (burden) is crucial for understanding links between exercise and cardiovascular outcomes in older endurance athletes (EA). Exercise burden, an integral of intensity and duration (MET·min), is typically determined from subjective self-reports but has uncertain accuracy. We studied 40 EAs (41 to 69 yrs., 50% female) with >10 yrs. training history, during a typical outdoor cycling training session (42 km). Subjective self-reports were related to cardiac (HR·min) and metabolic (MET·min) components of exercise burden, monitored continuously. Subjective self-reports were highly variable and underestimated objective metrics of exercise intensity. Discordance was observed between metabolic and cardiac burden as less fit individuals accrued greater cardiac (14039±2649 vs. 11784±1132 HR·min, P<0.01) but lower metabolic burden (808[plusmn]59 vs. 858[plusmn]61 MET·min, P<0.05) vs. higher fit EA. Caution is advised in interpreting MET·min estimates from self-reports, urging objective measurement of cardiac burden for further insights into the risk-benefit relationship of long-term exercise.

The authors have declared no competing interest.

Funding for this study was provided by the Canadian Institute for Health Research (CIHR), Operating Grant 130477 and from the Heart & Stroke/Richard Lewar Centres of Excellence.

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Approval for this study was provided by the University of Toronto Health Sciences Research Ethics Board (RIS RIS Human Protocol 39300).

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