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Christie L. Ward, Rudy J. Valentine and Ellen M. Evans

Adiposity, lean mass, and physical activity (PA) are known to influence physical function in older adults, although the independent influences are not completely characterized. Older adults (N = 156, M age = 68.9 ± 6.7 yr, 85 men) were assessed for body composition via dual-energy X-ray absorptiometry, PA by accelerometer, and physical function via timed up-and-go (UP&GO), 30-s chair stand, 6-min walk (6-min WALK), and Star-Excursion Balance Test. In the absence of percentage-body-fat by PA interactions (p > .05), main effects existed such that a higher percentage body fat was associated with poorer performance in UP&GO, 30-s chair stand, and 6-min WALK (p < .05). No significant main effects were found for PA and functional performance. Adiposity explains 4.6–11.4% in physical functional variance (p < .05). Preventing increases in adiposity with age may help older adults maintain functional independence.

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Rudy J. Valentine, Michael J. Saunders, M. Kent Todd and Thomas G. St. Laurent

Carbohydrate–protein (CHO+Pro) beverages reportedly improve endurance and indices of muscle disruption, but it is unclear whether these effects are related to total energy intake or specific effects of protein.

Purpose:

The authors examined effects of CHO+Pro on time to exhaustion and markers of muscle disruption compared with placebo (PLA) and carbohydrate beverages matched for carbohydrate (CHO) and total calories (CHO+CHO).

Methods:

Eleven male cyclists completed 4 rides to exhaustion at 75% VO2peak. Participants consumed 250 ml of PLA, CHO (7.75%), CHO+CHO (9.69%), or CHO+Pro (7.75%/1.94%) every 15 min until fatigue, in a double-blind design.

Results:

Time to exhaustion was significantly longer (p < .05) in CHO+Pro (126.2 ± 25.4 min) and CHO+CHO (121.3 ± 36.8) than PLA (107.1 ± 30.3). CHO (117.5 ± 24.2) and PLA were not significantly different. Similarly, CHO+Pro was not significantly different from CHO and CHO+CHO. Postexercise plasma creatine kinase was lower after CHO+Pro (197.2 ± 149.2 IU/L) than PLA (407.4 ± 391.3), CHO (373.2 ± 416.6), and CHO+CHO (412.3 ± 410.2). Postexercise serum myoglobin was lower in CHO+Pro (47.0 ± 27.4 ng/mL) than all other treatments (168.8 ± 217.3, 82.6 ± 71.3, and 72.0 ± 75.8). Postexercise leg extensions at 70% 1RM were significantly greater 24 hr after CHO+Pro (11.3 ± 4.1) than PLA (8.8 ± 3.7), CHO (9.7 ± 4.3), and CHO+CHO (9.5 ± 3.6).

Conclusion:

These findings suggest that at least some of the reported improvements in endurance with CHO+Pro beverages might be related to caloric differences between treatments. Postexercise improvements in markers of muscle disruption with CHO+Pro ingestion appear to be independent of carbohydrate and caloric content and were elicited with beverages consumed only during exercise.