Neck extensor fatigue: Comparing the effect of 45 degrees of neck flexion to the effect of 45 degrees of trunk flexion

Abstract

The neck muscle fatigue and subjective discomfort due to neck postural exposure was evaluated. Ten male participants were asked to hold one of the two static neck postural exposures for 30 minutes (one condition per day): 1) Neck flexion (N-45) where head and neck were flexed 45º relative to trunk while the participant was standing upright, and 2) Trunk flexion (T-45) where head and neck were not flexed relative to trunk, but trunk was flexed 45º. Surface electromyography was used to collect muscle activity of neck extensors. T-45 caused higher fatigue in neck extensor muscles (p=0.0229) and higher neck subjective discomfort (p=0.0088) compared to N-45, but the long-term effects of these two conditions are not clear because of the difference in the role of passive tissues. We recommend that work assessment tools consider both measures of neck postural exposure (neck flexion and trunk flexion) in their assessment tools.