THE FATIGUE OF STANDING

Abstract

Continuous standing is more fatiguing than walking; work performed standing produces greater fatigue than the same work sitting. The mechanism which creates this difference in fatigue is obscure. Stance oscillations are individual and repeatable. Stance oscillation data were ob-tained pre- and post-static effort of the lower extremities. Oscillation magnitude was increased, decreased, or both, reflecting individual susceptibility to fatigue. The mean locus was consistently disrupted suggesting wt. redistribution. Recumbent height and balance point were detd. by balance table pre- and post-static effort and pre- and post-continued standing. Transient lowering was induced in 96% by effort and in 94% by standing. This weight change represents considerable blood shift to lower extremity vascular reservoirs which suggests that early onset of fatigue while standing is due to cerebral hypoxia evoked through standing. The interpretation of the results of this study suggests that protracted standing evokes an excessive generation of nerve impulses, initiated through repetitious stimulation of antigravity musculature and through subacute cerebral hypoxia which lifts higher neural inhibitory control over lower equilibratory mechanisms, thus releasing excessive stimuli to antigravity muscles. The tonic antigravity musculature gives rise to volleys of sensory stimuli which produce discomfort, and find neural expression in efferent stimulation to other musculature with subsequent contraction and sensory reaction. Thus an additive sensory resultant is created impinging on consciousness as the fatigue of standing.