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Oral amino-acid provision does not affect muscle strength or size gains in older men


Medicine & Science in Sports & Exercise: July 2002 - Volume 34 - Issue 7 - p 1126-1131
BASIC SCIENCES: Original Investigations

GODARD, M. P., D. L. WILLIAMSON, and S. W. TRAPPE. Oral amino-acid provision does not affect muscle strength or size gains in older men. Med. Sci. Sports Exerc., Vol. 34, No. 7, pp. 1126–1131, 2002.

Purpose The intent of this investigation was to examine the effects of a daily oral provision consisting of amino acids (L-lysine, L-leucine, L-valine, L-phenylalanine, L-threonine, L-histidine, L-isoleucine, and L-methionine) in combination with carbohydrates (dextrose, sucrose, and fructose) on whole muscle strength and size characteristics during a 12-wk progressive knee extensor resistance training (PRT) program in older men (>65 yr).

Methods Seventeen older men were randomly assigned to either the experimental (EX) or control (CN) groups. The EX (N = 8) and CN (N = 9) groups had the following characteristics—EX: 70.8 ± 1.5 yr, 91.0 ± 4.9 kg, and 177.0 ± 3.9 cm; CN: 72.1 ± 1.9 yr, 75.4 ± 4.7 kg, and 176.1 ± 3.0. Pre and post PRT maximal unilateral isometric torque (N·m), isokinetic torque (1.05, 1.57, 2.09, 3.14, 4.19, and 5.24 rad·s−1), work capacity (30 consecutive reps at 3.14 rad·s−1) torque, one repetition maximum (1RM) bilateral isotonic strength, and whole muscle cross-sectional area (CSA) of the mid-thigh were performed by computed tomography on each subject.

Results All variables showed and improvement with training (P < 0.05); however, there were no differences between the groups. Both groups increased in isometric strength by 21%, and isokinetic torque by 24% to 11% with the varying velocities (1.05–5.24 rad·s−1). Whole muscle 1RM strength and thigh CSA increased 50% and 6.5%, respectively. Additionally, voluntary torque/CSA increased 12% in both the EX and CN groups (P < 0.05).

Conclusions In conclusion, these data suggest that whole muscle strength and size are not enhanced with a postexercise daily provision of an oral amino-acid complex during 12 wk of PRT in older men.

Human Performance Laboratory, Ball State University, Muncie, IN

Submitted for publication June 2001.

Accepted for publication January 2002.

©2002The American College of Sports Medicine