Acute Effects of Combined Hypoxia and Fatigue on Balance in Young Men

The aim of this study was to determine the effects of maximal exercise and maximal exercise under hypoxic conditions on balance, the strategies of the balance-maintenance process and its sensory organization. A total of 60 men were randomly allocated to three experimental groups and a control group. All participants completed the sensory organization test for assessing balance. Participants in the experimental groups performed the same test after an hour of normobaric hypoxia (the first group), after supramaximal exercise (the second group) and after supramaximal exercise combined with 60 min of hypoxia exposure (the third group). The control group performed the test after 60 min of passive rest. Normobaric hypoxia conditions corresponded to an altitude of 2950 m (FIO2 15%). Physical effort in normoxia and hypoxia significantly impaired the participants' stability on a stable platform with eyes open (eta 2 = 0.711, p = 0.001; eta 2 = 0.583, p = 0.001, respectively). On an unstable platform, a significant improvement in stability indices was observed in the group undertaking the exercise in hypoxia (p = 0.04, eta 2 = 0.249). The experimental conditions increased the role of hip strategies in maintaining balance in the experimental groups during trials requiring somatosensory information. An analysis of sensory organization shows that maximal effort in hypoxia increases the role of somatosensory (p = 0.002, eta 2 = 0.69) and vestibular (p = 0.02, eta 2 = 0.34) information, whereas hypoxia alone increases reliance on visual (p = 0.03, eta 2 = 0.38) and vestibular (p = 0.02, eta 2 = 0.36) information. This study indicates that individuals have poorer stability after maximal exercise, which may cause difficulties in engaging in some dynamic forms of activity, especially those with a large number of visual stimuli.