The influence of protein intake during resistance training on body composition and glucose metabolism in older men and women
Abstract
Aging is associated with negative alterations in body composition and glucose metabolism. Sarcopenia, age related muscle loss, is associated with decreased strength and physical function, and decreased glucose metabolism is associated with increased risk of developing type 2 diabetes mellitus. Given the ramifications of both diseases and the increasing number of older people, practical methods to combat these afflictions are needed. Both dietary protein intake and resistance training (RT) independently affect body composition and glucose metabolism, though their combined effect is largely undocumented in older people. To assess the efficacy of this intervention, 36 healthy older men and women (BMI 26 ± 1 kg/m2; 61 ± 1 y; mean ± SEM) completed a 12-week dietary and RT intervention. Subjects consumed either 0.9 ± 0.1 g protein·kg-1·d -1 (lower protein, LP) or 1.2 ± 0.0 g protein·kg -1·d-1 (higher protein, HP). Subjects remained weight stable, increased fat-free mass (2.0 ± 0.5 kg, P < 0.05), protein mass (0.5 ± 0.2 kg, P < 0.05) and total body water (1.6 ± 0.6 L, P < 0.05), and decreased fat mass (-1.2 ± 0.5 kg, P < 0.05) independent of group and gender. Vastus lateralis fiber cross-sectional area of all fiber types was unchanged with time (i.e., RT). Two-hour glucose area-under-the-curve (AUC, 75-gram glucose load) decreased with intervention, independent of protein intake (-994 ± 295 mg/dL per 2h, P < 0.05). Two-hour insulin and C-peptide AUC decreased in LP (-7164 ± 2922, -24472 ± 11045 pmo1·L-1·120min-1, respectively, P < 0.05) but were unchanged in HP (3550 ± 3198, 13505 ± 9419 pmo1·L-1·120min-1, respectively, P < 0.05; significant RT*protein intake interaction, P < 0.05). Though protein content of insulin receptor, insulin receptor substrate-1 and Akt were unchanged with RT (P>0.05), atypical protein kinase-C lambda/zeta protein content increased with RT, independent of protein intake and gender (P<0.05). Results from this study indicate that resistance training improves body composition and glucose metabolism in older people, and protein intake during resistance training influences how the improvement in glucose tolerance is achieved.
Degree
Ph.D.
Advisors
Campbell, Purdue University.
Subject Area
Nutrition|Gerontology
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