Bone marrow metabolism is impaired in insulin resistance and improves after exercise training.

CONTEXT Exercise training improves bone mineral density, but little is known about the effects of training on bone marrow (BM) metabolism. BM insulin sensitivity has been suggested to play an important role in bone health and whole-body insulin sensitivity. OBJECTIVE To study the effects of exercise training on BM metabolism. DESIGN Randomized controlled trial. SETTING Clinical research center. PARTICIPANTS Sedentary healthy (n=28, 40-55 years, all males) and insulin resistant subjects (IR) (n=26, 43-55 years, males/females 16/10). INTERVENTION Two weeks of sprint interval training or moderate-intensity continuous training. MAIN OUTCOME MEASURES We measured femoral, lumbar and thoracic BM insulin-stimulated glucose uptake (GU) and fasting free fatty acid uptake (FFAU) using positron-emission tomography and bone turnover markers from plasma. RESULTS At baseline, GU was highest in lumbar, followed by thoracic and lowest in femoral BM (all p<0.0001). FFAU was higher in lumbar and thoracic than femoral BM (both p<0.0001). BM FFAU and femoral BM GU were higher in healthy compared to IR men and in females compared to males (all p<0.05). Training increased femoral BM GU similarly in all groups and decreased lumbar BM FFAU in males (all p<0.05). Osteocalcin and PINP were lower in IR than healthy men and correlated positively with femoral BM GU and glycemic status (all p<0.05). CONCLUSIONS BM metabolism differs regarding anatomical location. Short-term training improves BM GU and FFAU in healthy and IR subjects. Bone turnover rate is decreased in insulin resistance and associates positively with BM metabolism and glycemic control.