Acute effects of walking at moderate normobaric hypoxia on gait and balance performance in healthy community-dwelling seniors: A randomized controlled crossover study.

BACKGROUND Hiking at moderate altitude is a popular outdoor activity in seniors. Acute exercise or altitude can diminish balance performance. Thus, the present study examined the combined effects of altitude and walking on static and dynamic balance. METHODS Thirty-six healthy seniors (age: 62 (SD: 4) y; BMI: 25 (5) kg/m(2)) were examined on three days. Firstly, walking velocity was determined at 85% of the first ventilatory threshold (VT1). Therefore, a ramp walking test on a treadmill was completed. On day two or three, a 40-minute treadmill walk under sea level or normobaric hypoxia (2600m) was performed using a random, double-blind study design. Balance performance was assessed on a force-plate during single leg stance with eyes open (SLEO, 10s on a force-plate) immediately before and after walking. Spatio-temporal gait characteristics were collected during walking at 5 and 35min. RESULTS Condition×time interaction effects were not found for either parameter (0.13<p<0.60; 0.007<ηp(2)<0.07). Only time effects were observed for cadence (-1.5%, p<0.001, ηp(2)=0.29), stride time (+2.3%, p=0.007, ηp(2)=0.28), and temporal gait variability (+22.6%, p=0.01, ηp(2)=0.16). A moderate time×condition effect was observed for postural sway during SLEO (p=0.04, ηp(2)=0.11). Subseqent post hoc testing revealed difference between hypoxia and normoxia at 35min (p=0.01) and between 5 and 35min testing during hypoxia and normoxia (both p<0.001). CONCLUSION Alterations of cadence, stride time, and temporal gait variability might be attributed to fatigue-induced changes of temporal gait adjustments. Normobaric hypoxia did not acutely impair gait patterns. We assume that demanding postural standing tasks that require more central control may be affected to a greater extent by altitude exposure.