Relationship between the level of mental fatigue induced by a prolonged cognitive task and the degree of balance disturbance.

This study investigated the effects of mental fatigue (MF) induced by a 90-min AX-continuous performance test (AX-CPT) on balance control by addressing the issue of the heterogeneity of individuals' responses. Twenty healthy young active participants were recruited. They had to carry out two balance tasks (sway as little as possible on a stable support with the eyes open and closed) when standing on a force platform before and after performing a 90-min AX-CPT. The NASA-TLX test was used to assess the subjective manifestations of MF. Objective cognitive performance was measured using results from the AX-CPT. Inter-individual differences in behavioral deterioration due to MF were analyzed with a hierarchical cluster analysis, which categorizes participants' behaviors into subgroups with similar characteristics. The cluster analysis revealed that the achievement of the AX-CPT induced various levels of MF and balance impairments within the whole sample. A significant relationship between the level of MF and the degree of balance disturbance was observed only when participants stood with the eyes open, thus suggesting that inter-individual differences in vulnerability to MF could stem from differences between subjects in the level of engagement of visual attention and/or from differences in field dependency for balance control. These findings show that the completion of the same prolonged demanding cognitive task induces a strong heterogeneity in subjects' responses, with marked individual differences in MF vulnerability that affect balance control differently according to the sensory context.

Balance control is impaired by mental fatigue due to the fulfilment of a continuous cognitive task or by the watching of a documentary.

The aim of the present study was to evaluate the effects of mental fatigue (MF) induced by a 90-min continuous demanding cognitive task on balance control. Twenty healthy young participants were recruited. They had to perform three postural tasks (on a stable support with eyes open, with eyes closed and on a wobble board) while standing on a force platform before and after watching a documentary in a control condition or carrying out a prolonged continuous demanding cognitive task (AX-continuous performance test-AX-CPT) in a MF condition. Results showed that performing the AX-CPT generated MF since participants felt a higher subjective workload from the NASA Task Load Index after the AX-CPT than after viewing the documentary. Both the AX-CPT and the viewing of the documentary impaired balance control, mainly by affecting postural regulatory mechanisms which evolved towards a less automatic and less complex regulation mode with an increased participation of cognitive resources. MF generated by the AX-CPT affected balance control by compromising the attentional processing, while the deleterious influence of watching a documentary on postural control could stem from an adverse effect of prolonged sitting on balance control during subsequent standing.

Correction to: Voluntary and electrically-induced muscle fatigue differently affect postural control mechanisms in unipedal stance.

In the metadata of the original publication of the article.