Neck musculature fatigue affects specific frequency bands of postural dynamics during quiet standing

Proprioceptive input from the neck is important for maintenance of upright standing. Although neck musculature fatigue has been demonstrated to impair standing balance, there is limited understanding of the underlying postural mechanisms. This study aimed to further examine the effects of neck musculature fatigue on standing by using modern analysis of center of pressure (CoP) data. Forty-eight young healthy adults stood quietly on a balance board for 1 min before and after performing repeated weight-resisted scapular elevation exercises. In a supplementary study on 20 participants, we examined (i) the effects of visual deprivation and (ii) the test-retest reliability of the traditional and wavelet-based CoP measures. Test-retest reliability of the CoP measures was moderate to good (intraclass correlation coefficients ranged from 0.58 to 0.94). With neck muscle fatigue or without vision, traditional measures of CoP velocity and standard deviation increased monotonically. Wavelet analysis revealed that CoP velocity within the ultralow (<0.10 Hz) and moderate (1.56-6.25 Hz) frequency bands increased post-fatigue. Without vision, CoP velocity increased in all but the ultralow frequency band. Our data suggest that post-fatigue, vision may be the main compensatory postural mechanism for altered neck proprioception. In conclusion, our findings reveal more nuances than the simple assertion that neck musculature fatigue increased postural sway and they advocate the use of wavelet analysis in examining postural mechanisms associated with neck proprioception.