Cytochrome oxidase changes in trapezius muscles with night vision goggle usage

Abstract

Decreases in cytochromeoxidase (CtOx) redox state has been hypothesized as a precursor to neck pain and myalgia. We monitored CtOxredox levels bilaterally in the trapeziusmuscle of pilots flying a simulator with night vision goggles (NVG) to investigate the effects of head-worn mass on CtOx values. Twenty male helicopter pilots (age = 36.9 ± 7.7 y; helicopter flight experience = 1548.3 ± 1504.8 h flying) volunteered to perform 2 missions (1 DAY & 1 NVG helmet configuration) of approximately 100 min in a full-motion flight simulator. Near infrared spectroscopy was used to monitor right and left upper trapezius muscles metabolism. Split plot repeated-measures were used to test for significant differences between DAY and NVG missions. CtOxduring the NVG missions were significantly reduced ( p = 0.007) by approximately 150–1600% as compared to baseline while the DAY missions resulted in an increased in CtOx values of approximately 400–2100% as compared to baseline. There were significant increases in blood volume ( p = 0.047) between mission conditions. Our results suggest that the additional mass of NVG negatively impacts the trapezius muscles' ability to perform aerobic respiration despite the lack of evidence of the occurrence of occlusion to the muscle. This provides insight as to why NVG flight is commonly described as a causative factor in neck pain among military aircrew. Relevance to industry Various militaries around the world have recently begun to document and investigate a growing concern with respect to neck pain among their helicopter aircrew. This paper supports an approach in which helicopter neck strain is investigated as being the result of chronic occupational exposure.