Jordan, Leora Y., authorMiller, Benjamin F., advisorHickey, Matthew S., committee memberMelanson, Ed, committee memberMelby, Christopher L., committee member2007-01-032007-01-032010http://hdl.handle.net/10217/37799Department Head: Richard Gay Israel.Sarcopenia is the progressive decline in muscle mass that happens with age and can lead to falls, fractures, and inability to maintain activities of daily living. Simplistically, sarcopenia results from a disequilibrium in the rates of muscle protein synthesis (MPS) and muscle protein breakdown (MPB), with a net negative protein and nitrogen balance over time. This study was designed to determine whether subjects in energy balance can increase nitrogen balance by timing milk intake immediately after exercise. In a randomized cross-over design, ten older individuals (64.5±2.0 y) completed two 3-day trials that were isocaloric and isonitrogenous. During the two trials, subjects consumed either chocolate milk (PRO+CHO) or a Kool-Aid type beverage (CHO) following a daily bout of cycling exercise (60 minutes at 55% of VO2max). Study diet was repeated across trials and controlled for protein/nitrogen content (1.2 g/kg and 14% of total kcal) and energy balance (within 200 kcal). For all trial days, 24-hour urine collections were completed and analyzed for nitrogen content. Mean energy balance (CHO+PRO: 202±36 kcal; CHO: 191±44 kcal; p=0.68) and mean physical activity level (PAL) (CHO+PRO: 1.61±0.04; CHO: 1.60±0.04; p=0.60) did not differ between trials, but mean nitrogen balance was significantly more positive in the PRO+CHO (1.2 g N±0.32) trial than the CHO trial (0.8 g N ±0.45) (p<0.05). Thus, under conditions of energy balance, nitrogen/protein balance becomes more positive when chocolate milk is consumed immediately after moderate intensity aerobic exercise compared to a CHO-only beverage.masters thesesengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.Text