Motor-cognitive dual-tasking under hypoxia.

Hypoxic conditions diminish motor performance and cognitive functions, especially when the motor task and the cognitive task are conducted simultaneously. Hypoxia does further increase prefrontal cortex activity which provokes a reduced capability of efficient resource utilisation. This, again, might evoke that the capacity of the limited mental resources of a dual task will be reached at an earlier stage of task complexity. The purpose of our study was to examine whether a cognitive task would increase gait variability to a higher extent under hypoxic as compared to normoxic conditions. 18 young subjects walked on a treadmill with and without performing a cognitive task under normoxic vs. normobar hypoxic conditions. The variability of stride times was calculated and a two-way ANOVA with repeated measurements was performed to compare single-task walking with a dual task under both environmental conditions. Furthermore, we compared the cognitive performance while walking in different conditions with Wilcoxon tests. An interaction effect (F 1,34 = 6.178; p = 0.018; η p2  = 0.154) was observed indicating that in the dual-task condition, there was a greater increase in gait variability in hypoxic conditions as compared to normoxic conditions. We further observed that under hypoxic conditions, each participant performed worse in the cognitive task while walking (p < 0.001). Hypoxia might decrease the ability of performing a motor-cognitive dual task. We speculate that performing a dual task under hypoxia requires a shift of resources away from prefrontal regions. However, future research should verify this assumption examining prefrontal cortex activity while dual-task walking under normoxic conditions to analyse the haemodynamic responses of the brain.