# Acute Effects of Combined Hypoxia and Fatigue on Balance in Young Men
## 4 Discussion  
In this study, we assumed that the two factors analyzed (fatigue and hypoxia) would differentially affect the sensory organization of balance maintenance. Furthermore, we expected a summative effect of their interaction. The above hypotheses were confirmed to a limited extent. Effort in normoxia and hypoxia impairs balance most strongly under reference conditions on a stable platform and with eyes open (ES 1). However, the combined effect of these stimuli does not exacerbate the impairment. Balance maintenance under dynamic conditions is enhanced by both normoxia and hypoxia conditions. Exercise only and effort in hypoxia under conditions requiring visual input (ES 4, ES 6) worsen postural stability. In dynamic conditions, the hierarchy of sensory inputs changes depending on the disturbing factor. Participants in hypoxia rely more on visual (VIS) and vestibular (VEST) information. Exertion in hypoxia increases the demand for somatosensory (SOM) and vestibular (VEST) information. An analysis of the changes in balance strategies indicates a decreasing role for the ankle joint strategy and an increasing role for the hip strategy under static conditions after exercise (also in hypoxia). In dynamic conditions, hypoxia, in turn, promotes a slight increase in the role of the ankle joint (ES 4, ES 5, ES 6) in postural stability. The process of maintaining balance is realized by integrating information from three sense organs (receptor inputs): vision, the proprioceptor system and the peripheral vestibular organ. The integration of this information both statically and dynamically allows the nervous system to refer to one of the three strategies described by [PERSON] and [PERSON] [29] to maintain balance: the ankle joint strategy, the hip joint strategy, the stride or a combination of these. Dynamic posturography allows an objective analysis of the participants' balance under dynamic conditions and is more suitable for young, healthy and athletic persons. It allows the assessment of the participants' use of vestibular, visual or somatosensory information. The assessment was carried out in six conditions. In the first \begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Variable [\%]** & **Group** & **Baseline Me \(\pm\) QD** & **Post Me \(\pm\) QD** & \(p\) & \(\eta^{2}\) \\ \hline SOM & C & 97.50 \(\pm\) 1.50 & 98.00 \(\pm\) 1.50 & 0.51 & \\  & H & 97.00 \(\pm\) 1 & 98.50 \(\pm\) 1 & 0.06 & \\  & F & 99.00 \(\pm\) 2.00 & 99.00 \(\pm\) 2.00 & 0.10 & \\  & FH & 96.00 \(\pm\) 1.00 & 99.00 \(\pm\) 1.00 & 0.002 & 0.69 \\ \hline VIS & C & 94.00 \(\pm\) 3.00 & 96.00 \(\pm\) 1.50 & 0.12 & \\  & H & 90.50 \(\pm\) 5.5 & 94.00 \(\pm\) 2.5 & 0.03 & 0.38 \\  & F & 93.00 \(\pm\) 4.50 & 96.00 \(\pm\) 5.50 & 0.66 & \\  & FH & 94.00 \(\pm\) 7.00 & 93.00 \(\pm\) 3.50 & 0.98 & \\ \hline VEST & C & 72.50 \(\pm\) 6.00 & 78.50 \(\pm\) 6.00 & 0.03 & 0.34 \\  & H & 70.00 \(\pm\) 5.5 & 78.50 \(\pm\) 6.5 & 0.02 & 0.36 \\  & F & 73.00 \(\pm\) 6.50 & 79.00 \(\pm\) 8.50 & 0.08 & \\  & FH & 68.00 \(\pm\) 8.50 & 80.00 \(\pm\) 7.00 & 0.02 & 0.34 \\ \hline VIS PREF & C & 103.00 \(\pm\) 2.00 & 104.50 \(\pm\) 2.00 & 0.58 & \\  & H & 100.50 \(\pm\) 6.5 & 97.00 \(\pm\) 5 & 0.15 & \\  & F & 96.00 \(\pm\) 5.00 & 96.00 \(\pm\) 4.00 & 0.44 & \\  & FH & 103.00 \(\pm\) 6.50 & 94.00 \(\pm\) 6.00 & 0.13 & \\ \hline \hline \end{tabular} SOM: somatosensory; VIS: visual; VEST: vestibular; VIS PREF: visual preference; C: control group; H: hypoxia-treated group; F: fatigue induced by anaerobic exercise; FH: fatigue induced by anaerobic exercise in hypoxia; Me—median; QD—quartile deviation; \(\eta^{2}\)—effect size.  
\end{table} 
Table 5: Effect of maximal effort in hypoxia and normoxia on the sensory organization of balance. three conditions, the ground (platform) was stable despite changing visual stimuli: eyes open, eyes closed and center of gravity (COG)-dependent movement of the visual surround.