Supramaximal testing is widely used to verify VO2max attainment, yet its efficacy in sedentary subjects is unknown. The aim of the study was to test this hypothesis in men and women completing maximal cycle ergometry. Fifteen sedentary subjects (age=22.4+/-3.9 year) completed incremental exercise, and returned at least 24 h later to complete constant load exercise at 105% peak work rate (Wmax). Another group of nine sedentary men and women (age=21.8+/-5 year) completed supramaximal exercise at 115% Wmax 1-1.5 h after incremental exercise. During exercise, gas exchange data and heart rate (HR) were continuously obtained. VO2max was similar (p>0.05) between incremental and supramaximal exercise in subjects in the first (32.32+/-4.81 mL/kg/min vs. 31.80+/-5.35 mL/kg/min) and second subset (40.63+/-3.61 mL/kg/min vs. 41.66+/-5.55 mL/kg/min). Maximal HR was lower (p<0.05) with supramaximal exercise, yet respiratory exchange ratio was higher (p<0.05). Test-retest reliability (r=0.81-0.89, p<0.05) for VO2max was high during repeated bouts of supramaximal testing. Findings support use of this protocol to confirm VO2max attainment in healthy, sedentary men and women completing incremental cycle ergometry.

New approaches to inducing altitude acclimation in a relatively short timeframe are needed, as it is not practical for many soldiers and athletes to gain access to specialized training facilities. Acclimation to one environmental stressor could enhance adaptation to various other stressors in animals and humans. This phenomenon has been described as cross-tolerance and involves the activation of common protective pathways. The purpose of this review is to discuss possible mechanisms involved in the cross-tolerance between heat and hypoxia. Future data could potentially support the use of a cross-tolerance model as a means for military personnel to prepare for deployment to high-altitude environments, as well as for athletes competing at high altitude.

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