Date

5-2013

Advisor

Wayne W. Campbell

Department

Foods and Nutrition

Major

Nutrition Science

Keywords

muscle efficiency, gross mechanical efficiency, substrate utilization, elderly, cycle ergometer, protein supplementation

Abstract

Objective:

This study assessed the effect of increased dietary protein intake on adaptation of energy expenditure and skeletal muscle function at rest and during low-intensity physical activity in elderly adults.

Methods:

Using a randomized, crossover design, 12 adults (7 F, 5 M), aged 82 7 y (mean SD) completed two 6-day periods of consuming fruit-smoothie beverages twice daily (with breakfast and lunch) containing 230 kcal and 25 g whey protein (WPro) or 25 g corn-derived glucose polymer (CHO) (total 460 kcal/day and 50 g/day WPro or CHO).

Results:

On day 7 of each period, fasting blood urea nitrogen was 28 9% higher in WPro vs. CHO (P=0.003), consistent with higher total protein intake. Fasting state energy expenditure and respiratory ratio at rest and while exercising on a stationary cycle at 1, 10, 20 watts were not different between WPro and CHO. Gross mechanical efficiency of skeletal muscle progressively increased from 1 to 10 to 20 watts, but this response was not different between WPro and CHO.

Conclusion:

Short-term supplementation with either whey protein or glucose polymer does not differentially influence fasting state whole body substrate utilization or skeletal muscle work efficiency in elderly adults.

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