The Effect of Acetyl-L-Carnitine and Exercise on the Mechanical Function of Aged Medial Gastrocnemius Muscles in Male Fisher 344 Rats
Aging is associated with sarcopenia, the severe loss of skeletal muscle mass and strength, which can contribute to physical frailty, vulnerability to injury, and loss of independence in the elderly population. Endurance exercise and acetly-L-carnitine (ALCAR) supplementation have been shown to benefit skeletal muscle function by increasing oxidative capacity. This study tested the hypothesis t hat ALCAR supplementation and exercise will increase muscle mass and enhance contractile function in aging skeletal muscle. Contractile function of medial gastrocnemius (MGN) muscles of young-mature (7 month), mature (13 month), and senescent (25 month) male Fisher 344 rats was evaluated following 12 weeks of either ALCAR supplementation (150 mg/kg/day), treadmill exercise, or both. Isolated medial gastrocnemius muscle mass was generally lower in the 25 compared to the 7 and 13 month old animals, although significant only in the ALCAR and exercise groups. Sustained power (W/kg) during repetitive stimulation in the 25 month old control was generally lower compared to 7 and 13 month old control muscles. In the 25 month old animals, exercise, but not ALCAR supplementation, enhanced the ability to sustain power compared to controls. ALCAR in combination with exercise did not enhance sustained power above that observed with exercise alone. Therefore, it appears that ALCAR may not prevent the age-associated loss of muscle mass and function.