Impact of forearm fatigue on the postural response to an externally initiated, predictable perturbation

• Published in: European journal of applied physiology Vol. 114; no. 7; pp. 1473 - 1481
• Main Authors: Kennedy, Ashleigh, Guevel, Arnaud, Sveistrup, Heidi
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2014; Springer Nature B.V; Springer Verlag
• Subjects: Adaptation, Physiological; Adaptation, Physiological Anticipation, Psychological Biomechanical Phenomena Electromyography Female Forearm Hand Strength Humans Male Muscle Contraction Muscle Fatigue Muscle, Skeletal / innervation Muscle, Skeletal / physiology Posture Recovery of Function Time Factors; Anticipation, Psychological; Biomechanical Phenomena; Biomedical and Life Sciences; Biomedicine; Electromyography; Female; Forearm; Hand Strength; Human Physiology; Humans; Life Sciences; Male; Muscle Contraction; Muscle Fatigue; Muscle function; Muscle, Skeletal - innervation; Muscle, Skeletal - physiology; Nervous system; Occupational Medicine/Industrial Medicine; Original Article; Posture; Production capacity; Recovery of Function; Sports Medicine; Time Factors; Canada; Central fatigue; Anticipatory postural response; Recovery; Posture
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-014-2880-3

Purpose
The objective was to examine the impact of non-postural muscle fatigue on anticipatory postural control, during postural perturbations induced by platform translations. The experimental setup investigated the central changes caused by fatigue without the potential confounding influence of peripheral fatigue within the postural muscles.
Methods
Fatigue induced in forearm muscles by a maximal handgrip contraction has been previously shown to influence forearm force production for 10 min, reduce ankle plantarflexion force for 1 min and create measureable central fatigue for 30 s. The peak-to-peak anterior/posterior displacement of the center of mass and center of pressure (COP) and muscle activity were measured during the postural perturbation tasks performed before the fatigue protocol and for 10 min post-fatigue.
Results
The fatigue protocol decreased the peak-to-peak COP displacement from 128.0 ± 12.3 mm pre-fatigue to 81.9 ± 7.8 mm post-fatigue during the forwards platform translation (
p
 < 0.05) and from 133.8 ± 12.0 to 89.2 ± 7.9 mm during the backwards translation (
p
 < 0.05). The fatigue protocol also caused the tibialis anterior (TA pre-fatigue = −0.25 ± 0.04 s, TA post-fatigue = −0.41 ± 0.02 s,
p
 = 0.001) and medial gastrocnemius muscles (MG pre-fatigue = −0.39 ± 0.03 s, MG post-fatigue = −0.48 ± 0.02 s,
p
 = 0.028) to be recruited significantly earlier relative to the pre-fatigue condition.
Conclusion
This experimental setup ensured that peripheral fatigue did not develop in the postural muscles; therefore, a general fatigued-induced modification of the postural strategy is proposed as the origin of the postural changes and delayed recovery.