Effects of exercise during head-down bed rest on postural control.
BACKGROUND
The effects of exercise on postural control during walking were evaluated following exposure to head-down bed rest (BR).


METHODS
Two groups of male subjects (N = 18, mean age = 21.4 yr +/- SE 1.0) were exposed to 5 d of 6 degrees head-down bed rest. The experimental group (E) exercised 90 min.d-1 (n = 12 subjects) during the BR while the control group received no intervention (n = 6). The exercise treatment consisted of a combination of isotonic and isokinetic lower extremity exercise training. Electromyographic (EMG) activity in the tibialis anterior, gastrocnemius, vastus lateralis, and biceps femoris was measured during walking before and after BR.


RESULTS
Following BR, EMG activity increased in both test subject groups for all muscles (p < 0.05). However, there were no significant differences in EMG activity between the C and E groups either before or after BR.


CONCLUSIONS
These data suggest that the ability of the postural control system to adjust to the gravitational environment was compromised as a result of BR. In addition, we conclude that the exercise protocol used was not an effective countermeasure to the alterations in the postural control system.
Davis
J E
JE
Department of Exercise and Health Science, Alma College, MI 48801, USA.
Horwood
K E
KE
DeJong
G K
GK
D000328:Adult; D000704:Analysis of Variance; D001510:Bed Rest / Q000009:adverse effects; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D018475:Head-Down Tilt / Q000009:adverse effects; D006801:Humans; D018472:Hypogravity / Q000009:adverse effects; D007866:Leg / Q000503:physiopathology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D011187:Posture / Q000502:physiology; D012021:Reflex, Abnormal / Q000502:physiology*; D018561:Space Simulation / Q000009:adverse effects