The effect of lumbar support on the effectiveness of anti-G straining manuevers.
BACKGROUND
The ability of fighter pilots to perform efficient anti-G straining maneuvers (AGSM) is vital for their G-tolerance. The aim of this study was to evaluate if the use of a lumbar support that optimizes the posture of the spine enhances the effectiveness of AGSM.


METHODS
Eleven fighter pilots performed four AGSM training sessions with 4-5 repetitions in each session, each lasting approximately 10 s. The sessions were done without lumbar support or using supports that were 7, 14, or 26 mm thick. During the sessions, the electromyogram (EMG) data were recorded from eight muscles (rectus and biceps femoris, gluteus maximus, erector spinae, rectus abdominis, obliquus externus, latissimus dorsi, and pectoralis major).


RESULTS
In a single best AGSM, average EMG (aEMG) increased 12%, 10%, and 14% and power spectrum area (PSA) increased 20%, 26%, and 44% while using 7-, 14-, and 26-mm supports, respectively, in relation to the condition without support. According to aEMG and PSA, effectiveness increased in 11 and 10 subjects, respectively, with the average increase being 12% (aEMG) and 25% (PSA). During the whole session (repeated AGSM), effectiveness was best with support in 7 subjects and without support in 4 subjects. In the total population, the average increase in the effectiveness during repeated AGSM was 6% and 11% with aEMG and PSA, respectively.


CONCLUSIONS
The use of lumbar support tended to increase the effectiveness of muscular work, especially during single AGSM, but also during repeated AGSM.
Oksa
Juha
J
Oulu Regional Institute of Occupational Health, Laboratory of Physiology, Oulu, Finland. juha.oksa@ttl.fi
Linja
Tero
T
Rintala
Harri
H
D000328:Adult; D000337:Aerospace Medicine; D004576:Electromyography; D005387:Finland; D006112:Gravitation; D006801:Humans; D008297:Male; D008889:Military Personnel; D018482:Muscle, Skeletal / Q000502:physiology; D011187:Posture; D011482:Protective Devices; D013131:Spine / Q000502:physiology*