Body fatness, insulin sensitivity and muscle oxygen supply in adolescents

Muscle blood flow can be reduced in insulin-resistant states. The present study examined the importance of body fatness and insulin sensitivity as variables that may be associated with muscle oxygen supply. We studied 38 adolescents (22 males, 16 females; age 15.3–18.6 years; body mass index 17.7–34.7kg/m²) and used near-IR spectroscopy to measure the muscle re-oxygenation rate after ischaemic finger flexion exercise. Total body fat content was estimated by bioelectrical impedance analysis, and insulin sensitivity was assessed by homoeostasis model assessment. Regional lipid compartments were also assessed for potential associations with muscle oxygen supply. Abdominal adiposity (visceral and subcutaneous) was assessed by magnetic resonance imaging, and soleus intramyocellular lipid levels were determined by magnetic resonance spectroscopy. Total body fat content (r = 0.67, P<0.001), abdominal subcutaneous fat area (r = 0.78, P<0.001), abdominal visceral fat area (r = 0.54, P<0.001) and intramyocellular lipid levels (r = 0.68, P<0.001) were significantly related to forearm re-oxygenation half-time. After adjusting for insulin sensitivity, both total body fat content (r = 0.395, P = 0.02) and abdominal subcutaneous fat area (r = 0.543, P = 0.001) remained positively associated with relatively reduced muscle oxygen supply in adolescent subjects. After adjusting for body fat content, abdominal subcutaneous fat area (r = 0. 511, P = 0.002) was significantly associated with muscle oxygen supply. Thus muscle oxygen supply is associated with body fat content, and certain fat compartments may be more influential than others.