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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 - pp 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