Posture and Helmet Load Influences on Neck Muscle Activation

Area of Science:

• Aerospace Medicine
• Human Factors Engineering
• Occupational Biomechanics

Background:

• Night vision goggles (NVG) are associated with increased neck muscle strain and pain.
• Counterweights (NVGcw) are proposed to alleviate these symptoms.
• Understanding the biomechanical effects of NVGs and counterweights is crucial for aircrew safety.

Purpose of the Study:

• To investigate the effects of different helmet loads and head postures on neck muscle activation in helicopter aviators.
• To determine if counterweights effectively reduce muscular response compared to NVGs alone.

Main Methods:

• Sixteen male helicopter aviators (pilots and flight engineers) participated.
• Subjects assumed nine head postures under four load conditions (no helmet, helmet only, NVG, NVGcw).
• Neck muscle activation was measured using electromyography (EMG) on four bilateral muscle groups.

Main Results:

• Neck muscle activation increased two- to fourfold with NVGs or NVGcw compared to no helmet, particularly in postures to the left.
• Smaller muscles (sternocleidomastoid, splenius capitis) showed greater activation increases than larger muscles (trapezius).

Conclusions:

• Night vision goggle counterweights did not significantly decrease neck muscle activity compared to NVGs alone.
• The effectiveness of counterweights was limited, especially when head posture was below the horizon.
• Task-specific guidelines and countermeasures are recommended to mitigate neck muscle activity and fatigue in aircrew using NVGs.