EFFECT OF MODERATE EXERCISE ON INSULIN SENSITIVITY AND SUBSTRATE METABOLISM DURING POSTEXERCISE RECOVERY IN CIRRHOSIS

We examined whether a single bout of moderate exercise has a beneficia l effect on insulin sensitivity and fuel homeostasis in cirrhosis. Cli nically stable cirrhotic patients and age-, sex-, and weight-matched c ontrols participated in insulin clamp studies (either euglycemic hyper insulinemic or hyperglycemic hyperinsulinemic) in combination with ind irect calorimetry and [6,6-H-2(2)]glucose. Three to seven days later, studies were repeated following a single bout of exercise (30 minutes of treadmill exercise at 60% of maximal aerobic capacity), After an ov ernight fast, following exercise, both cirrhotic and control individua ls showed a shift in fuel utilization to enhanced lipid oxidation, dec reased glucose oxidation, and increased nonoxidative glucose disposal rates (i.e., glycogen synthesis in muscle) when compared with pre-exer cise rates but differences were statistically significant only in the patient group. During euglycemic hyperinsulinemia, insulin-mediated gl ucose disposal was significantly reduced in cirrhotic patients (3.43 /- 0.26 vs. 7.36 +/- 0.48 mg/kg/min, P <.01), Following exercise, gluc ose uptake increased significantly in cirrhotic patients when compared with pre-exercise levels (P <.05) but remained unchanged in the contr ol group. The increase in total body glucose disposal in cirrhotic pat ients was entirely accounted for by an increase in nonoxidative glucos e disposal (0.81 +/- 0.20 vs. 0.51 +/- 0.15 mg/kg/min, P <.05). During combined hyperglycemia/hyperinsulinemia, however, insulin sensitivity was unaffected by exercise in both patients and control individuals, In summary, in cirrhotic patients, a single bout of moderate exercise 1) causes a shift a in substrate utilization with an increase in lipid oxidation in the postexercise period that is significantly more prono unced than in controls, and 2) increases insulin sensitivity only duri ng euglycemia but not during the more physiological condition of hyper glycemia. Single bouts of moderate exercise therefore may not have a b eneficial effect on the metabolic status of patients with chronic live r disease.