Acceleration effects on neck muscle strength: pilots vs. non-pilots.
BACKGROUND
Conditioning of neck muscles, if any, due to repeated exposures to +Gz forces has received little research attention.


OBJECTIVE
This study was conducted to evaluate and compare the neck muscle strength of test volunteers representative of the general populations of fighter aircraft pilots and non-pilots.


METHODS
The tests were performed using a special attachment device on a computerized dynamometer. Ten pilots and ten non-pilots volunteered as test subjects. Each individual's maximal isometric neck muscle strength was evaluated in the extension, flexion, and left and right lateral bending directions in a single day. Peak values from the measurements were used for data analysis. Overall neck strength was calculated as the mean values for the four directions in each group.


RESULTS
The overall muscular strength of the necks of pilots did not differ significantly from that of non-pilots, nor did exposure to +Gz forces lead to specific changes in isometric muscle strength across any of the four principal directions. Neck muscle strength in the four measured directions pooled across the two subgroups were statistically significant. The widespread practice of adopting protective head-positioning strategies to minimize neck strains, coupled with results from this research study, suggest that the neck muscles are subjected to reduced in-flight strengthening workouts during exposures to +Gz forces.


CONCLUSIONS
To maximize in-flight performance and minimize +Gz-induced neck injuries, fighter pilots should be encouraged to perform on-land neck muscle strengthening exercise and in-flight head-positioning techniques. More research is needed to fine-tune this countermeasure strategy against cervical spine injury.
Seng
Kok-Yong
KY
Human Effectiveness Lab, Defence Medical Research Institute, Defence Science and Technology Agency, Singapore. kyseng@dsta.gov.sg
Lam
Pin-Min
PM
Lee
Vee-Sin
VS
D000328:Adult; D000337:Aerospace Medicine; D001696:Biomechanical Phenomena; D006257:Head; D006801:Humans; D018471:Hypergravity / Q000009:adverse effects*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D009333:Neck / Q000502:physiology*; D019838:Neck Injuries / Q000517:prevention & control; D010809:Physical Fitness; D011187:Posture