Cardiorespiratory Responses to a Maximal Graded Exercise Test on a Treadmill Versus All-Extremity Non-Weight-Bearing Ergometer in Healthy Older Adults

Treadmill exercise (TE) is widely used in graded exercise testing protocols to evaluate cardiorespiratory fitness. However, individuals with lower body musculoskeletal complaints and balance impairments, particularly older adults, may not tolerate TE. All-extremity non-weight-bearing exercise (ANE) on an air-braked ergometer eliminates weight-bearing concerns, allows compensation for unilateral or bilateral lower extremity weakness or fatigue while activating a large amount of muscle mass in the legs, arms and trunk. Thus, ANE may allow a larger portion of older adults to undergo graded exercise testing. A previous study has shown that cardiorespiratory fitness was similar in response to a TE vs. ANE maximal graded exercise test in middle-aged healthy adults, but in older healthy adults this has not been investigated. Therefore, the purpose of this study was to investigate the hypothesis that cardiorespiratory responses to a TE vs. ANE graded exercise test are similar in healthy older adults. Twenty-one sedentary, healthy older adults (mean±SD: 67±5 yrs) completed a maximal graded exercise test on a treadmill and an ANE air-braked ergometer, on separate visits at least two weeks apart. Cardiorespiratory fitness was determined using oxygen consumption via open circuit spirometry. We found no significant difference in maximal test duration (mean±SE: 12.5±0.5 vs. 12.3±0.6 min, P=0.8), maximal heart rate (158±3 vs. 154 ±3 beats/min, P=0.1), and maximal rate of perceived exertion (18.6±0.3 vs. 19.0±0.2, P=0.2) in the TE vs. ANE tests. However, cardiorespiratory fitness was higher in response to the TE test (25.8±1.1 vs. 23.6±1.2 ml/kg/min, P=0.001). In conclusion, despite comparable maximal test duration, heart rates and perceived exertions between the two exercise modalities, a higher cardiorespiratory fitness level was attained during the maximal graded exercise test on the treadmill. The mechanisms underlying the attenuated cardiorespiratory fitness in response to a maximal graded exercise test on an ANE air-braked ergometer merits further investigation. This work was supported by the National Institute of Aging grant AG063143. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.