ELECTROMYOGRAPHIC INDICES OF MUSCLE FATIGUE DURING SIMULATED AIR COMBAT MANEUVERING

Authors
  1. Bain, B.
  2. Jacobs, I.
  3. Buick, F.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
Abstract
Pilots exposed to high levels of headward (+Gz) acceleration must perform voluntary muscle contractions in order to maintain head-level arterial pressure. To study the possibility that muscular fatigue can limit human +Gz duration tolerance, elctromyographic (EMG) activity and EMG indices of muscular fatigue were measured during a simulated air combat maneuvering (SACM) centrifuge profile. Eight experienced male volunteers were exposed to a +4-7 Gz centrifuge profile until volitional fatigue. Electrical activity (EMG) was recorded from 7 muscles: biceps brachii (BB), latissimus dorsi (LD), pectoralis major (PM), rectus abdominis (RA), vastus lateralis (VL), biceps femoris (BF) and gastrocnemius (GN). EMG and force during isometric contractions of the same muscles were also recorded at 1 G. Root mean square (RMS) and mean power frequency (MPF) were calculated for each second of EMG data. G-tolerance time averaged 256 plus or minus 33 s (mean plus or minus SD). RMS activity was expressed relative to activity during a maximal muscle contraction. The mean val ues (%) for each muscle during the 7 Gz plateaux were: RA, 30.8; BB, 26.4; LD, 4 4.0; PM, 48.5; VL, 43.4; BF, 31.4; GN, 39.3. The estimated level of contraction relative to a MVC (%) was: RA, 36.6; BB, 30.5; LD, 43.9 and PM 61.4. There was n o significant difference between contraction levels for any of the muscles studi ed. TRUNCATED
Keywords
Muscle fatigue;AGSM (Anti-G straining maneuver)
Report Number
DCIEM-92-33 — Reprint
Date of publication
01 Jun 1993
Number of Pages
6
Reprinted from
Aviat Space Environ Med, vol 65, 1994, p 193-198
DSTKIM No
94-02662
CANDIS No
141436
Format(s):
Hardcopy;Originator's fiche received by DSIS

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