Neck muscle activity in skydivers during parachute opening shock.

Area of Science:

• Sports Medicine
• Biomechanics
• Human Physiology

Background:

• Epidemiological data suggests a link between skydiver neck pain and parachute opening shock (POS).
• Understanding the biomechanical forces and muscle responses during POS is crucial for injury prevention.

Purpose of the Study:

• To investigate skydiver neck muscle activity and activation timing during POS.
• To determine if anticipatory motor control strategies are employed to mitigate POS-related neck strain.

Main Methods:

• Observational study involving 20 experienced skydivers performing terminal velocity skydives.
• Surface electromyography (EMG) measured bilateral neck and upper shoulder muscle activity.
• Triaxial accelerometers recorded deceleration during POS; muscle activity normalized to % MVE.

Main Results:

• Neck muscle activity during POS reached mean magnitudes of 53-104% MVE.
• Activation occurred rapidly, with mean temporal onsets <50 ms after POS onset (9-34 ms latencies).
• High muscle activity, particularly in lower posterior neck and upper shoulders, indicates substantial cervical strain.

Conclusions:

• Skydivers exhibit significant neck muscle activation during POS, suggesting substantial cervical spine strain.
• Rapid, anticipatory muscle activation is a likely protective strategy against POS-induced injury.
• Findings support the need for preventative strategies to address POS-related neck pain in skydivers.