Low Appendicular Lean Mass Index and Associations with Metabolic and Demographic Parameters in Wheelchair Athletes with Spinal Cord Injury.

Abstract

People suffering from spinal cord injury (SCI) undergo metabolic and physical disturbances that target the skeletal muscle, causing a progressive loss of muscle mass. To estimate the appendicular lean mass index (ALMI) in athletes with traumatic (T-group) and non-traumatic (NT-group) SCI, and its association with metabolic and demographic parameters. Wheelchair athletes with SCI aged 18 to 52 years old were included (n = 62). From DEXA assessment, we estimated the ALM index (ALMI = appendicular lean mass/height2) and classified participants according to the degree of muscle loss (ALMI < 2 SD from the reference populations). Fasting blood was assayed for glycaemia, insulin, cortisol, and IGF-1 serum levels. Data were compared by T-test and Fisher's Exact Test; predictors of ALMI were investigated by linear regression models. The frequency of low ALMI was 63% in overall sample, 55% T-group and 71% NT-group. Low ALMI had no significant association with the origin of injury (X2 = 1.1, p = 0.29). Linear regression analyses showed significant association, in the whole sample, between ALMI and serum levels of IGF-1 (Beta = 0.69; p < 0.001), age (Beta=-5.8; p < 0.001), percentage fat mass (Beta=-0.26; p = 0.001), and energy intake (Beta = 0.32; p = 0.02). These significances were not maintained in the NT-group sub-analyses. Low ALMI was very frequent in our SCI participants, despite exercising and independently of the type of injury. Metabolic and demographic variables associated with low ALMI were different according to the origin of injury, which possibly relies on physiopathology particularities. More studies are necessary to clarify our findings.