Insulin resistance in paraplegics--effect of one bout of acute exercise

Insulin action was assessed in spinal cord injured (SCI) male individuals (n = 5) and compared to controls (C) (n = 5). Mean (+/-SD) age and body weight were 27.0 +/- 5.1 and 24.5 +/- 1.6 years and 68.6 +/- 3.2 and 76.6 +/- 5.0 kg for SCI and C group, respectively. Subjects performed physical activities 2-3 times/week on a non-competitive basis. Using the euglycemic clamp, metabolic clearance rate of glucose (g-MCR) was measured twice, one week apart; at a basal state and then 1 h after aerobic exercise. Exercise consisted of 60 min arm-crank at 20-25 watt and 60 rpm. During the hyperinsulinemic clamp, insulin concentration was 76 +/- 14 and 67 +/- 9 microU.ml-1, in SCI and in controls, respectively. At baseline, g-MCR was comparable in SCI and C individuals (8.1 +/- 2.4 and 8.0 +/- 2.1 ml.kg-1.min-1, respectively). After exercise, g-MCR remained at 7.9 +/- 2.0 and 8.5 +/- 2.6 ml.kg-1.min-1 in SCI and C, respectively. In spite of muscle atrophy, peripheral sensitivity to insulin was not impaired in paraplegics. No increase in insulin response to the exercise stimulus was seen in any of the groups. It may thus be suggested that the daily level of activity and the physical training performed by paraplegics, are sufficient to eliminate a state of insulin resistance, which often develops in extremely sedentary populations.