Head positioning and neck muscle activation during air combat

Area of Science:

• Aerospace Medicine
• Biomechanics
• Sports Science

Background:

• Acute neck injuries in aviation are often linked to +Gz forces, but the precise mechanisms remain unclear.
• Understanding head positioning and cervical muscle activation during air combat is crucial for mitigating injury risk.

Purpose of the Study:

• To quantify head positions adopted by aircrew during air combat maneuvers.
• To determine the levels of cervical muscle activation associated with these head positions and +Gz exposure.

Main Methods:

• Surface electromyography (EMG) was used to record neck erector spinae (ES) and sternocleidomastoid (SC) muscle activation in six fast jet aircrew.
• EMG signals were normalized to maximum voluntary contraction (MVC), and data were synchronized with in-cockpit video and +Gz acceleration.
• Subjects flew air combat sorties, and their head position and muscle activation were analyzed during engagements.

Main Results:

• Aircrew maintained non-neutral head positions (predominantly extension or rotation plus extension) for 68% of the air combat time.
• Neck extension under G resulted in 40-80% MVC in ES, reduced by 50% with canopy support.
• Significant sternocleidomastoid (SC) activation occurred during combined neck extension and rotation, with ES active >40% MVC for 25% of engagement duration.
• A 35% reduction in neck muscle strength was observed post-sortie.

Conclusions:

• Extreme head extension and rotation are prevalent during air combat, leading to substantial cervical muscle activation and fatigue.
• Findings provide a basis for developing targeted neck conditioning and positioning strategies to reduce the risk of acute neck injury in aircrew.