VOLUME CHANGES IN THE LEGS OF PARAPLEGIC SUBJECTS DURING ARM EXERCISE

The purpose of this study was to examine the inability of paraplegic ( P) subjects to redistribute fluid below the spinal cord lesion during arm exercise, with emphasis on the role of the sympathetic system in t his redistribution failure. Fifteen male P and 15 male able-bodied [co ntrol (C)] subjects performed arm cranking exercise, and volume change s in the calf were measured by strain gauge plethysmography before, du ring, and after exercise. Muscle pump activity in the legs of C subjec ts was eliminated. The rate of calf volume decrease at the beginning a nd halfway points of the exercise period, the total volume decrease du ring exercise, and the volume increase during recovery were significan tly lower in P than in C subjects. Whereas completeness of the lesion had no influence on leg volume changes, the rate of calf volume decrea se at the beginning of exercise and the total volume decrease during e xercise were significantly correlated with the level of the spinal cor d lesion. This study confirms that P subjects are unable to redistribu te fluid effectively below the spinal cord injury during arm exercise, which is partly caused by a loss of sympathetically induced vasoconst riction and which appears to be independent of the completeness of the lesion but dependent on its level.