Helicopter cockpit seat side and trapezius muscle metabolism with night vision goggles

Introduction: Documented neck strain among military helicopter aircrew is becoming more frequent and many militaries use helicopters that provide pilots with the option of sitting in the left or right cockpit seat during missions. Purpose: The purpose of this study was to use near infrared spectroscopy (NIRS) to investigate the physiological changes in trapezius muscle oxygenation and blood volume during night vision goggle (NVG) flights as a function of left and right cockpit seating. Methods: There were 25 pilots who were monitored during NVG flight simulator missions (97.7 +/- 16.1 min). Bilateral MRS probes attached to the trapezius muscles at C7 level recorded total oxygenation index TOI, %), total hemoglobin (tHb), oxyhemoglobin (Hb(O2)), and cleoxyhemo-globin (HHb). Results: No significant differences existed between variables for pilots seated in the right cockpit seat as compared with the pilots seated in the left cockpit seat in either trapezius muscle (pTOI = 0.72; ptHb 0.72; pHb(O2) = 0.57; pHHb = 0.21). Conclusion: Alternating cockpit seats on successive missions is not a means to decrease metabolic stress for helicopter pilots using NVG. This suggests that cockpit layout and location of essential instruments with respect to the horizontal and the increased head supported mass of the NVG may be important factors influencing metabolic stress of the trapezius muscle.