Elsevier

Nutrition

Volume 20, Issue 5, May 2004, Pages 420-427
Nutrition

Applied nutritional investigation
Effect of a 10-Week strength training program and recovery drink on body composition, muscular strength and endurance, and anaerobic power and capacityā˜†

https://doi.org/10.1016/j.nut.2004.01.005Get rights and content

Abstract

Objective

We investigated whether postexercise consumption of a supplement containing whey protein, amino acids, creatine, and carbohydrate combined with a strength training program promotes greater gains in fat-free mass (FFM), muscle strength and endurance, and anaerobic performance compared with an isocaloric, carbohydrate-only control drink combined with strength training.

Methods

The study was double blind and randomized, and the experimental supplement was compared with a carbohydrate-only control. Forty-one males (n = 20 in control group, n = 21 in the supplement group; mean age, 22.2 y) participated in a 4 d/wk, 10-wk periodized strength training program. Subjects had to complete at least 70% of the workouts. Before and after 10 wk of strength training, subjects were tested for body composition by using hydrostatic weighing and skinfold thicknesses, one repetition maximum strength and muscular endurance for the bench press and 45-degree leg press, and anaerobic performance using a 30-s Wingate test. Thirty-three subjects (80.5%) completed the training program (n = 15 in control group, n = 18 in the supplement); these 33 subjects also completed all post-training test procedures. Data were analyzed with two-way analysis of variance with repeated measures on time. P ā‰¤ 0.05 was set as statistically significant. All statistical analyses, including calculation of effect size and power, were completed with SPSS 11.0.

Results

Across groups, FFM increased during 10 wk of strength training. Although there was no statistically significant time Ɨ group interaction for FFM, there was a trend toward a greater increase in FFM for the supplement group (+3.4 kg) compared with the control group (+1.5 kg; P = 0.077). The effect size (Ī·2 = 0.100) was moderately large. Percentage of body fat declined and fat mass was unchanged; there were no differences between groups. One repetition maximum strength for the bench press and 45-degree leg press increased, but there were no differences between groups. Muscular endurance expressed as the number of repetitions completed with 85% of the one repetition maximum was unchanged; external work, which was estimated as repetitions completed Ɨ resistance used, increased for the 45-degree leg press but not for the bench press over the 10-wk training period; there were no time Ɨ group interactions for either measurement. Anaerobic power and capacity improved, but there were no differences between groups for these variables or for fatigue rate.

Conclusions

Consumption of a recovery drink after strength training workouts did not promote greater gains in FFM compared with consumption of a carbohydrate-only drink; however, a trend toward a greater increase in FFM in the supplement group suggests the need for longer-term studies. Performance variables such as muscle strength and endurance and anaerobic performance were not improved when compared with the carbohydrate-only group.

Introduction

Research studies have demonstrated the effectiveness of creatine1, 2, 3 and the importance of protein4, 5, 6 for enhancing gains in muscle mass and strength. Creatine supplementation in conjunction with resistance training results in greater increases in fat-free mass (FFM)1, 2 and muscle fiber size2 than does training alone. The effects of creatine supplementation on FFM and muscle size may be due in part to an improved capacity to perform repeated bouts of high-intensity exercise such as strength training exercise.1, 7, 8, 9, 10 In addition, some studies have suggested that creatine may directly affect muscle growth,11, 12, 13, 14 whereas other studies have not supported these findings.15, 16 Regardless of the mechanisms of action, creatine supplementation enhances gains in FFM, muscle mass, and muscle strength when used in conjunction with a strength training program.2, 3

The increased protein needs of athletes have been recognized.5, 6, 17, 18 Protein supplementation also may improve gains in muscle mass when used in conjunction with strength training.4 After 6 wk of resistance training, groups that received whey protein or whey protein plus creatine had significant increases in lean tissue mass, but the placebo group did not have a significant gain in lean mass.4 However, not all studies have found protein supplementation to be beneficial for increasing muscle mass.17

In addition, optimizing the timing of nutrient intake may be essential for promoting maximal gains in muscle mass and strength in conjunction with a resistance training program. Ingestion of essential amino acids after heavy resistance exercise resulted in a change from net muscle protein degradation to net muscle protein synthesis.19 When essential amino acids are ingested in combination with carbohydrates at 1 or 3 h after exercise, muscle protein synthesis is stimulated.20 The greatest effect of a protein plus carbohydrate supplement on muscle protein synthesis is expected when the supplement is ingested immediately before or after the exercise bout.20, 21, 22, 23

Optimizing the amount and timing of carbohydrate intake also may have a significant effect on muscle glycogen content and protein turnover. Carbohydrate ingestion immediately after exercise promotes glycogen synthesis.24, 25, 26 This may decrease recovery time after strength training, enabling an increased training volume, which may enhance muscle mass and strength gains.27 Consumption of a carbohydrate solution after resistance training can enhance the rate of muscle glycogen repletion.28 Muscle glycogen content can be reduced by leg-extension exercise. In one study, muscle glycogen content 6 h after exercise had returned to 91% of initial values when a carbohydrate solution was consumed immediately after exercise and 1 h after exercise; however, muscle glycogen was only 75% of pre-exercise values when a placebo was consumed.28 Postexercise supplementation with carbohydrate and amino acids is as effective as a carbohydrate-only supplement for promoting muscle glycogen synthesis.29

Carbohydrates also may be beneficial during postexercise recovery by enhancing protein turnover. Carbohydrate consumption induces increases in circulating insulin levels and skeletal muscle blood flow,30 which may create a positive anabolic environment. Carbohydrate supplementation of 1 g/kg of body weight immediately after resistance training reduces myofibrillar protein breakdown.31

Research demonstrating that the ingestion of protein alone21 or protein and carbohydrate20, 23 before or after resistance training exercise improves protein turnover, providing a basis for hypothesizing that supplementation with protein plus carbohydrate near the time of exercise will improve muscle mass. However, it has not been demonstrated that the transient improvements in protein turnover after consumption of protein plus carbohydrate postexercise result in greater gains in muscle mass over longer periods of training.

Companies that manufacture and market dietary supplements are designing specific products for athletes and fitness enthusiasts. Anabolic Recovery, which is marketed by MET-Rx (Boca Raton, FL, USA), was designed to enhance protein turnover and glycogen resynthesis after exercise. A more rapid recovery after strenuous exercise workouts may allow individuals to train with greater volume or intensity on subsequent days. Also, consumption of a postexercise supplement may shift protein turnover more in the direction of protein accretion, thus increasing gains in FFM. A product containing whey protein and specific amino acids, creatine, and carbohydrate would provide convenience and possibly enhance gains in FFM, muscle function, and anaerobic performance. The purpose of this study was to determine whether postexercise consumption of a supplement drink (Anabolic Recovery) containing whey protein, specific amino acids, creatine, and carbohydrate combined with a strength training program promotes greater improvement in FFM, muscle strength and endurance, and anaerobic power and capacity as compared with strength training and an isocaloric, carbohydrate-only drink.

Section snippets

Study design

The study was a double-blind, placebo-controlled design. Subjects were randomly assigned to the supplement group or the control group.

Subjects

Forty-four males between ages 18 and 35 y (mean age, 22.2 y) were recruited for the study. Subjects had to be healthy based on a routine medical screening from the university health center or the subject's private physician. Subjects had to be physically active (minimum of 1 h and maximum of 5 h of strenuous exercise weekly on a regular basis) and have less than

Workouts completed and doses of supplement or control drink received

Thirty-three subjects (80.5%) completed the training program and follow-up testing (n = 15 in control group, n = 18 in supplement group). There were no differences between groups for the number of supervised and total workouts completed or the number of doses of supplement or control consumed (Table V). For those who completed the study, subjects in the control group completed 85.8% of the workouts and subjects in the supplement group completed 84.8% of all workouts. Subjects in the control

Discussion

Postexercise consumption of a drink containing creatine, whey protein, amino acids, and carbohydrates did not result in greater improvements in body composition, muscle strength and endurance, and anaerobic performance compared with the carbohydrate-only drink during a 10-wk strength training program. Although the postexercise supplement did not promote greater gains in FFM than did consumption of a carbohydrate-only drink, a trend toward a greater increase in FFM in the supplement group and a

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    ā˜†

    This study was supported by a grant from Numico USA, Inc.

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