J. Max Michel, Michael J. Berry, FACSM, Peter H. Brubaker, FACSM, Gary D. Miller. Wake Forest University, Winston-Salem, NC.

BACKGROUND: It is well established that the aging process induces a loss of skeletal muscle (SM) size and quality, and anabolic resistance (AR) is commonly implicated in this process. AR is defined as blunted muscle protein synthesis rates in response to common anabolic stimuli. As such, many trials have examined resistance training (RT) and increases to protein (PRO) intake, two potent anabolic stimulators. RT has been shown to attenuate, or in some instances reverse the age related deterioration of SM. Additionally, enhanced PRO intake has been shown to augment benefits to SM outcomes seen from RT alone. While promising results have been reported, the ideal paradigm of PRO intake in conjunction with RT remains to be revealed. Therefore, the purpose of this study is to examine the effects of graded PRO intake combined with a 10-week (wk) RT intervention on lean soft tissue mass (LSTM), SM tissue thickness, and strength outcomes. METHODS: Up to 20 participants over 55 years will be recruited for this study. All participants will undergo a 10-wk progressive RT intervention, performing 3 sessions per wk; and will be randomized to one of two groups: a constant PRO intake (CP) or graded PRO intake (GP). The CP group will be asked to consume 0.8-1.0 g of PRO per kilogram (kg) of body weight per day. The GP group will be asked to consume PRO in a graded manner that increases throughout the 10 wks of the study, beginning at 0.8 g/kg/day at wk 1 and reaching a peak of 2.2 g/kg/day. The GP group will be provided a whey protein (WP) supplement to assist in achieving desired PRO intake levels. DXA scans will be used to assess total and regional LSTM, and ultrasonography will be used to assess vastus lateralis (VL) tissue thickness at baseline and wk 10. Isokinetic dynamometry to assess peak torque of the knee extensors and flexors, and 3 repetition maximums (3RM) of the leg press and leg extension will constitute strength measures, taken at baseline, wk 5, and wk 10. Data will be analyzed using either one-way or two-way between measures ANCOVAs with baseline values as covariates. ANTICIPATED RESULTS: It is hypothesized that graded PRO intake + RT will produce greater increases in DXA derived LSTM, VL thickness, and strength measures than will constant PRO intake + RT. This study is being funded by the Wake Forest University Translational Science Center and the Department of Health and Exercise Science.

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