The association between regional body composition and metabolic outcomes in athletes with spinal cord injury

Abstract

Study design: Cross-sectional study comparing athletes with spinal cord injury (SCI) and age and body mass index matched able-bodied controls (AB). Objective: To examine the impact of exercise training on the relation between whole body, regional and intermuscular adipose tissue (IMAT) and glucose tolerance, insulin action and lipid profile. Setting: University Research Laboratory, USA. Methods: Fourteen college-aged athletes with SCI (seven men; duration of injury 16.575.7 years, level of injury T5-L5) and 17 sedentary AB (eight men) were assessed for body composition via dual-energy X-ray absorptiometry (DXA) and magnetic resonance imaging. Insulin sensitivity index (ISI) was determined via 2-h oral glucose challenge; standard lipid profile was determined from fasting blood samples. Results: Although ISI was 30% higher in SCI, there were no significant differences between groups in glucose and insulin responses or in lipid measures. Adjusting for absolute and relative thigh IMAT area, fasting insulin (13.875.3 mIU, 16.375.6 mIU; Po0.05; SCI vs AB respectively) and ISI (4.071.4, 3.171.3; Po0.05) were significantly better among SCI athletes compared to AB. Measures of adiposity did not correlate with glucose response or most lipid measures. Within SCI and AB, respectively, ISI correlated strongly (all Po0.05) with absolute (r ¼ À0.70, À0.54) and relative IMAT (r ¼ À0.54, À0.50), than with trunk (r ¼ À0.62, À0.64) and whole body fat mass (r ¼ À0.61, À0.64). Conclusion: Habitual physical activity can maintain insulin sensitivity in SCI compared to sedentary AB controls. Total body fat mass, central adiposity and thigh IMAT appear to impact risk for metabolic disease in SCI individuals with IMAT playing a larger role in SCI than AB.

Effect of Exercise on Disorders of Carbohydrate and Lipid Metabolism in Adults With Traumatic Spinal Cord Injury: Systematic Review of the Evidence

“…Only 3 subjects were assigned to each group, and no control group was included for comparison. There were 12 studies that reported carbohydrate-related outcomes (9,10,(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) (Table 1) and 15 that reported lipid-related outcomes (9,10,26,27,30,(35)(36)(37)(38)(39)(40)(41)(42)(43)(44) (Table 2). Only 1 study included cardiovascular morbidity as an endpoint (Table 2), and this was assessed using a survey instrument with variable levels of sensitivity and specificity when tested in able-bodied populations (45).…”

“…Of the 3 survey studies, one identified a statistically significant inverse correlation (r 5 20.53; P , 0.05) between reported levels of physical activity and fasting serum glucose (9). Another identified an inverse correlation (r 5 20.40) that was not statistically significant (10), whereas the third found no difference in glucose levels between athletes with SCI and a sedentary, able-bodied population (35).…”

“…However, the latter study did identify a statistically significant inverse correlation (r 5 20.79; P , 0.01) between physical activity and 2-hour postload insulin (10), whereas the former study did not (r 5 20.155). The third survey identified no significant differences in fasting plasma insulin levels, insulin area under the curve, or in insulin sensitivity index between athletes with SCI and a sedentary, able-bodied population (35).…”

“…We identified 16 studies involving 369 individuals that reported lipid- (9,10,26,27,30,(35)(36)(37)(38)(39)(40)(41)(42)(43)(44) or cardiovascular-(45) related outcomes ( Table 2). The overall quality of SCI-specific evidence supporting exercise as a therapy for lipid metabolism disorders was low (46,47).…”

“…Of these, only 2 considered baseline glucose or insulin measures in analysis or discussion (32,33). Three survey studies assessed the association between self-reported physical activity and carbohydrate-related measures (9,10,35). The most commonly assessed carbohydrate-related measures involved oral glucose tolerance tests (OGTTs), measuring post-oral load levels of glucose and insulin.…”