Aim: To detennine whether repetitive ann work, with a large component of static muscle contraction alters glucose metabolism and insulin sensitivity.

Methad: Euglycemic clamps (2h) were started in ten healthy individuals 15 minutes after 37 minute periods of: 1) repetitive ann work in a simulated occupational setting; 2) dynamic concentric exercise on a cycle ergometer at 60% OfVO2 max and 3) a resting regime as a control. During the experimental periods, blood samples were collected, blood pressure was measured repeatedly and electrocardiogram (ECG) wasrecorded continuously. During the clamps, euglycemia was maintained at 5 mmo1/l and insulin was infused at 56 mU/m2/min for 120 min.

Results: The insulin-mediated glucose disposal rate (M-value) for the steady state period (60- 120 min) of the clamp, tended to be lower following ann work than for both cycling and resting regimes. When dividing the steady state period into 20-minute intervals, the insulin sensitivity index, (ISI) was significantly lower for ann work compared with the resting control situation between 60-80 minutes (p=0.04) and 80-100 minutes (p=0.01) respectively.

Catecholamines increased significantly for ann work and cycling compared with resting regime. .Data from heart rate variability (HRV) me asurements indicated significant sympathetic activation during repetitive ann work test.

Canelusian: The results indicate that repetitive ann work might acutely promote insulin resistance, whereas no such effect on insulin resistance was produced by dynamic concentric exercise.