L-Arginine supplementation does not enhance blood flow and muscle performance in healthy and physically active older women.

PURPOSE: The purpose of this study was to examine the effects of acute L-arginine (L-arg) supplementation on peripheral vasodilatation and muscle performance in older women. METHODS: In a double-blind, randomized, placebo-controlled study, 20 elderly women were randomly assigned in a double-blind fashion to either an L-arg (ARG, N = 10) or placebo (PLA, N = 10) group. During the first visit, both groups underwent a Doppler ultrasound exam (to assess the femoral artery vasodilatation) at rest (baseline), and immediately before and after the isokinetic strength test (performed at 80 min after supplementation). On the second and third visits, the groups completed a battery of muscle performance tests (to assess the isometric and functional strength), initiated at the same time point (80 min after supplementation). RESULTS: The femoral artery blood flow (ARG: 443.9 ± 42.8 vs. PLA: 373.1 ± 40.8 ml/min; P > 0.05) and area (ARG: 0.45 ± 0.03 vs. PLA: 0.41 ± 0.02 cm(2); P > 0.05) were similar between the groups at basal conditions, and they remained unchanged after supplementation. Following exercise, blood flow increased ~160 % above the basal level, and there was no significant (P > 0.05) difference between the ARG and PLA groups. Additionally, there were no significant (P > 0.05) differences between the ARG and PLA groups for any strength variable (isokinetic, isometric, and functional). CONCLUSION: These results show that acute L-arg supplementation provides no ergogenic effect on blood flow and muscle performance in older women.

A single set of exhaustive exercise before resistance training improves muscular performance in young men.

PURPOSE: The purpose of this study was to examine the effects of an additional set of exhaustive exercise before traditional hypertrophic training on quadriceps muscle performance in young men. METHODS: Subjects performed maximal dynamic strength (1RM), local muscular endurance (LME), and magnetic resonance imaging (MRI) tests before and after an 8-week hypertrophic training program using a knee extensor machine. After baseline testing, the subjects were divided into 3 groups: untrained control, traditional training (TR), and prior exhaustive training (PE). Both the TR and PE groups trained using the same training protocol (2 days week(-1); 3 sets of 8-12 repetitions at 75 % of 1RM); the only difference was that the PE group performed an additional set of exhaustive exercise at 20 % of 1RM before each training session. RESULTS: After 8 weeks, the PE group experienced a greater (P < 0.05) increase in 1RM, cross-sectional area, and LME than the TR group. Additionally, no changes (P > 0.05) in daily dietary intake were observed between groups. CONCLUSION: These results suggest that the inclusion of a single set of exhaustive exercise at 20 % of 1RM before traditional hypertrophic training can be a suitable strategy for inducing additional beneficial effects on quadriceps strength, hypertrophy, and endurance in young men.

A single set of exhaustive exercise before local muscular endurance training improves quadriceps strength and endurance in young men.

BACKGROUND: The purpose of this study was to examine the effects of an additional set of exhaustive exercise before local muscular endurance (LME) training on maximal dynamic strength and endurance of quadriceps muscle in young men. METHODS: Twenty-seven healthy men (age: 20.9±1.8 years) performed one repetition maximum (1RM), muscular endurance, and magnetic resonance imaging (MRI) tests on two separate occasions (before and after an 8-wk LME training program using a bilateral knee extensor machine). After baseline testing, the subjects were divided into three groups: untrained control (CO, N.=9), traditional training (TR, N.=9), and prior exhaustive training (PE, N.=9). Both the TR and PE groups trained using the same LME training protocol (2 d∙wk-1; 3 sets of 15-20 repetitions at 50% of 1RM) throughout the 8-wk experimental period; the only difference was that the PE group performed an additional set of exhaustive exercise at 80% of 1RM immediately before each training session. RESULTS: After 8 wk, the PE group experienced a greater (P<0.05) increase in 1RM, endurance, and work efficiency than the TR group. Additionally, no changes (P>0.05) in cross-sectional area (CSA), body mass and daily dietary intake were observed from pre- to post-test in either group. CONCLUSIONS: These results suggest that the inclusion of a single set of exhaustive exercise at 80% of 1RM immediately before LME training can be a suitable strategy for inducing additional beneficial effects on quadriceps strength and endurance in young men.