title: Neck muscle activity in skydivers during parachute opening shock.
abstract: This observational study investigated skydiver neck muscle activity during parachute opening shock (POS), as epidemiological data recently suggested neck pain in skydivers to be related to POS. Twenty experienced skydivers performed two terminal velocity skydives each. Surface electromyography quantified muscle activity bilaterally from the anterior neck, the upper and lower posterior neck, and the upper shoulders; and two triaxial accelerometers sampled deceleration. Muscle activity was normalized as the percentage of reference maximum voluntary electrical activity (% MVE); and temporal muscle activity onset was related to POS onset. Our results showed that neck muscle activity during POS reached mean magnitudes of 53-104% MVE, often exceeding reference activity in the lower posterior neck and upper shoulders. All investigated muscle areas' mean temporal onsets occurred <50 ms after POS onset (9-34 ms latencies), which is consistent with anticipatory motor control. The high muscle activity observed supports that the neck is under substantial strain during POS, while temporal muscle activation suggests anticipatory motor control to be a strategy used by skydivers to protect the cervical spine from POS. This study's findings contribute to understanding the high rates of POS-related neck pain, and further support the need for evaluation of neck pain preventative strategies.
authors.affiliation: Department of Neurobiology, Care Sciences and Society, Karolinska Institutet Huddinge, Stockholm, Sweden.
authors.forename: R
authors.initials: R
authors.lastname: Lo Martire
authors.affiliation: Department of Neurobiology, Care Sciences and Society, Karolinska Institutet Huddinge, Stockholm, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Gladh
authors.affiliation: Department of Neurobiology, Care Sciences and Society, Karolinska Institutet Huddinge, Stockholm, Sweden.|Department of Physiology and Pharmacology, Karolinska Institutet Solna, Stockholm, Sweden.|Department of Anesthesia and Intensive Care Medicine, Karolinska University Hospital, Huddinge, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Westman
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet Solna, Stockholm, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Lindholm
authors.affiliation: Department of Neurobiology, Care Sciences and Society, Karolinska Institutet Huddinge, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Nilsson
authors.affiliation: Department of Neurobiology, Care Sciences and Society, Karolinska Institutet Huddinge, Stockholm, Sweden.
authors.forename: B O
authors.initials: BO
authors.lastname: Äng
mesh_terms: D061725:Accelerometry; D000328:Adult; D001359:Aviation; D003654:Deceleration; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000502:physiology; D009334:Neck Muscles / Q000502:physiology*; D019547:Neck Pain / Q000503:physiopathology*; D012782:Shoulder / Q000502:physiology; D019415:Torque
keywords: Anticipatory; biomechanics; cervical spine; electromyography; neck pain; skydiving