Progressive resistance training prevents loss of muscle mass and strength in bile duct-ligated rats

BACKGROUND: Loss of muscle mass and strength is common in cirrhosis and increases the risk of hyperammonaemia and hepatic encephalopathy. Resistance training optimizes muscle mass and strength in several chronic diseases. However, the beneficial effects of resistance training in cirrhosis remain to be investigated. Bile duct-ligated (BDL) rats develop chronic liver disease, hyperammonaemia, reduced muscle mass and strength. Our aim was to test the effects of resistance training on muscle mass, function and ammonia metabolism in BDL-rats.

METHODS: A group of BDL-rats underwent a progressive resistance training programme and a group of non-exercise BDL-rats served as controls. Resistance training comprised of ladder climbing with a progressive increase in carrying weights attached to the tail. Training was performed 5 days a week during 4 weeks. Muscle strength and body composition were assessed using grip strength and EchoMRI. Weight and circumference of the gastrocnemius muscle (normalized to bodyweight), plasma ammonia and glutamine synthetase protein expression and activity were assessed.

RESULTS: BDL + exercise rats had significantly larger gastrocnemius circumference compared to non-exercise BDL-rats: ratio 0.082 vs 0.075 (P < 0.05). Gastrocnemius muscle weight was higher in exercisers than controls: 0.006 vs 0.005 (P < 0.05). A tendency towards a lower plasma ammonia in the exercise group compared to controls was observed (P = 0.10). There were no differences in lean body mass, GS protein expression and activity between the groups.

CONCLUSION: Resistance training in rats with chronic liver disease beneficially effects muscle mass and strength. The effects were followed by non-significant reduction in blood ammonia; however, a tendency was observed.