Nutritional Interventions in Skeletal Muscle Atrophy

Abstract

Skeletal muscle atrophy occurs with prolonged bed rest, limb immobilization, microgravity, physical inactivity, and advancing age. This study evaluated the efficacy of a carbohydrate‐protein (+ leucine) supplement (Pacific Health Laboratory) to reduce muscle mass loss and maintain muscle physiological function in a rat atrophy model of hindlimb unloading (HU). Rats were fed high (CPH) and low (CPL) doses of the supplement or vehicle (HOH) (n=10/group) and were suspended by their tails to remove all weight‐bearing function on their hindlimbs for 28 days. The supplement (5 ml/kg) or vehicle (H2O) was administered twice daily via gavage, excluding the naïve control (CON) group (n=10); all rats were fed rat chow ad libitum. On day 28 in‐situ force measurements of the left lateral gastrocnemius were recorded in all HU groups (CPL, CPH, and HOH). Statistical analyses utilized ANOVA and the Dunnett's method. Muscle weights of the soleus (−36%), plantaris (−16%), and gastrocnemius (−21%) were significantly reduced in HOH, CPL, and CPH rats after 28 days of HU (p<0.05 compared to CON). The nutritional treatment (CPL and CPH) did not reduce muscle mass loss induced by HU. Specific in‐situ tetanic tension (maximal force/cross‐sectional area) of the left lateral gastrocnemius muscle was significantly less in the HOH group (17.2 N/cm2) compared to CPL (20.2 N/cm2, p<0.05) and CON groups (20.4 N/cm2, p<0.05). The specific tension of the CPL group did not differ significantly from the CON group. The CPH group's specific tension (19.2 N/cm2) did not significantly differ from either the HOH or CON groups. This carbohydrate‐protein (+ leucine) nutritional supplement was able to maintain muscle function (specific tension) but not muscle mass. Pacific Health Cooperation and The University of Texas at Austin supported this research.