Quote[/b] (American Journal of Clinical Nutrition @ Vol. 70, No. 6, 1032-1039, December 1999)]
Effects of an omnivorous diet compared with a lactoovovegetarian diet on resistance-training-induced changes in body composition and skeletal muscle in older men1,2,3
Wayne W Campbell, Marvin L Barton, Jr, Deanna Cyr-Campbell, Stephanie L Davey, John L Beard, Gianni Parise and William J Evans
Background: Very limited data suggest that meat consumption by older people may promote skeletal muscle hypertrophy in response to resistance training (RT).
Objective: The objective of this study was to assess whether the consumption of an omnivorous (meat-containing) diet would influence RT-induced changes in whole-body composition and skeletal muscle size in older men compared with a lactoovovegetarian (LOV) (meat-free) diet.
Design: Nineteen men aged 51–69 y participated in the study. During a 12-wk period of RT, 9 men consumed their habitual omnivorous diets, which provided 50% of total dietary protein from meat sources (beef, poultry, pork, and fish) (mixed-diet group). Another 10 men were counseled to self-select an LOV diet (LOV-diet group).
Results: Maximal strength of the upper- and lower-body muscle groups that were exercised during RT increased by 10–38% (P < 0.001), independent of diet. The RT-induced changes in whole-body composition and skeletal muscle size differed significantly between the mixed- and LOV-diet groups (time-by-group interactions, P < 0.05). With RT, whole-body density, fat-free mass, and whole-body muscle mass increased in the mixed diet group but decreased in the LOV- diet group. Type II muscle fiber area of the vastus lateralis muscle increased with RT for all men combined (P < 0.01), and the increase tended to be greater in the mixed-diet group (16.2 ± 4.4 %) than in the LOV diet group (7.3 ± 5.1%). Type I fiber area was unchanged with RT in both diet groups.
Conclusion: Consumption of a meat-containing diet contributed to greater gains in fat-free mass and skeletal muscle mass with RT in older men than did an LOV diet.
1 From the Nutrition, Metabolism, and Exercise Laboratory, Donald W Reynolds Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock
2 the Geriatric Research, Education, and Clinical Center, Central Arkansas Veterans Healthcare System, Little Rock
3 the Noll Physiological Research Center and the Department of Nutrition, The Pennsylvania State University, University Park; and the Department of Kinesiology, McMaster University, Hamilton, Canada.