BACKGROUND: Aerobic exercise capacity provides information regarding cardiorespiratory health and physical capacity. However, in many populations the ability to measure whole-body or leg aerobic exercise capacity is limited due to physical disability or lack of appropriate equipment. Clinically there is a need to evaluate aerobic capacity in individuals who cannot use their legs for locomotion. In astronauts the habitable space for exercise testing in the next generation of space exploration systems may be restricted and may not support the traditional lower body testing. Therefore, the purpose was to determine if upper body physical performance could estimate lower body aerobic capacity.METHODS: Maximal O₂ uptake (<inline-graphic xlink:href="amhp4181inf1.gif"/>o_2max), gas exchange threshold (GET), and the highest sustainable rate of aerobic metabolism [arm cranking critical power (_ACP) and lower body critical speed (_LCS)] were determined in 55 conditioned men and women during arm-cranking and treadmill running.RESULTS: <inline-graphic xlink:href="amhp4181inf1.gif"/>o_2max and GET (48.6 ± 7.6 and 29.0 ± 4.8 ml · kg⁻¹ · min⁻¹, respectively) were significantly lower during arm-cranking exercise compared to running (27.1 ± 7.6 and 13.5 ± 2.6 ml · kg⁻¹ · min⁻¹, respectively). The <inline-graphic xlink:href="amhp4181inf1.gif"/>o₂ at _ACP was significantly lower than the <inline-graphic xlink:href="amhp4181inf1.gif"/>o₂ at the _LCS (18.4 ± 5.01 vs. 39.5 ± 8.1 ml · kg⁻¹ · min⁻¹, respectively). There was a significant correlation between arm-cranking and lower body <inline-graphic xlink:href="amhp4181inf1.gif"/>o_2max, GET, and the <inline-graphic xlink:href="amhp4181inf1.gif"/>o₂ at _LCS and _ACP. Backward stepwise regression analyses revealed that arm-cranking physical fitness could explain 67%, 40%, and 49% of the variance in lower body <inline-graphic xlink:href="amhp4181inf1.gif"/>o_2max, GET, and _LCS, respectively.DISCUSSION: Results suggest arm-cranking exercise can be used to obtain an approximation of lower body aerobic capacity.Ade CJ, Broxterman RM, Craig JC, Schlup SJ, Wilcox SL, Barstow TJ. Upper body aerobic exercise as a possible predictor of lower body performance. Aerosp Med Hum Perform. 2015; 86(7):599–605.