Motor strategy during postural control is not muscle fatigue joint-dependent, but muscle fatigue increases postural asymmetry

Abstract

The aim of this study was to investigate the effects of ankle and hip muscle fatigue on motor adjustments (experiment 1) and symmetry (experiment 2) of postural control during a quiet standing task. Twenty-three young adults performed a bipedal postural task on separate force platforms, before and after a bilateral ankle and hip muscle fatigue protocol (randomized). Ankle and hip muscles were fatigued separately using a standing calf raise protocol (ankle fatigue) on a step and flexion and extension of the hip (hip fatigue) sitting on a chair, at a controlled movement frequency (0.5Hz), respectively. In both experiments, force, center of pressure, and electromyography parameters were measured. The symmetry index was used in experiment 2 to analyze the postural asymmetry in the parameters. Our main findings showed that muscle fatigue impaired postural stability, regardless of the fatigued muscle region (i.e., ankle or hip). In addition, young adults used an ankle motor strategy (experiment 1) before and after both the ankle and hip muscle fatigue protocols. Moreover, we found increased asymmetry between the lower limbs (experiment 2) during the quiet standing task after muscle fatigue. Thus, we can conclude that the postural motor strategy is not muscle fatigue joint-dependent and a fatigue task increases postural asymmetry, regardless of the fatigued region (hip or ankle). These findings could be applied in sports training and rehabilitation programs with the objective of reducing the fatigue effects on asymmetry and improving balance.

Effects of Physical and Mental Fatigue on Postural Sway and Cortical Activity in Healthy Young Adults

“…Nonetheless, our results are in line with previous research, which reported fatigue-related impairments for balance performance and, thus, postural control resulting in significant increases in postural sway ( Sadowska and Krzepota, 2016 ; Penedo et al, 2021 ), sway velocity ( Zech et al, 2012 ), sway area ( Bedo et al, 2020 ; Moon et al, 2020 ; Penedo et al, 2021 ), as well as decreases of the stability index ( Cooper et al, 2020 ) during stable and unstable bipedal and unipedal stance in healthy young adults. For instance, Zech et al (2012) investigated the effects of a localized fatigue versus a general fatigue protocol on static and dynamic balance in male handball athletes.…”

“…Accordingly, they assumed that there might exist different sensorimotor control mechanisms within the postural control system responsible for static and dynamic balance which are affected differently by the applied fatigue protocols. Moreover, Penedo et al (2021) examined the effects of local PF on postural sway and lower limb muscle activation in healthy young adults. While postural sway increased, no changes in muscle activation were observed after PF.…”

“…While postural sway increased, no changes in muscle activation were observed after PF. The authors suggested that impairments in postural control emerge from deteriorated proprioception as well as from changes within the peripheral and central systems ( Penedo et al, 2021 ).…”

Sex differences in the effect of muscle fatigue on static postural control under different vision and task conditions

“…In addition, a fatigue-induced shift of the mean ML COP position to the right was found during the QS-EO task in the present study (shift to a more positive value indicating a shift to the right; Fig 2B ), possibly suggesting a fatigue-induced asymmetry of posture. This would be consistent with the results of a recent study showing an increased asymmetry index between preferred and non-preferred legs (based on muscle activation during quiet standing) with ankle and hip muscle fatigue, possibly indicating a shift in the control of posture towards the preferred leg [ 42 ]. This suggests that the contribution of a more reliable leg to control posture could increase with fatigue.…”

Analysis of the Stability of the Body in a Standing Position When Shooting at a Stationary Target―A Randomized Controlled Trial

“…This definition is used to describe a temporary decline in the ability to perform physical activities [ 63 , 64 ]. As reported in the literature, muscle fatigue reduces postural stability, regardless of the tired muscle area, and the asymmetry of the load on the lower limbs increases [ 65 , 66 ].…”