Health Psychology Home Page
Papers written by students providing scientific reviews of topics related to health and well being
|Search||Home | Weight Loss | Alternative Therapy | Supplements | Eating Disorders | Fitness | Links | Self-Assessment | About this Page ||
Protein Supplementation and Weightlifting
Protein supplements have become a staple product of the dietary and health supplement industry. Whether it is in a bar, powder or beverage, protein supplements are one of the most widely known and utilized forms of supplementation in the fitness industry. Protein supplementation is most intrinsically associated with weightlifting, strength and resistance training, as well as other athletic pursuits. Protein and amino acids are touted as the basis for building muscle mass and increasing performance in weightlifting. This paper aims to evaluate the claims that are made about protein supplementation’s effect on muscle growth and improving strength; it will evaluate these claims by reviewing the scientific literature on protein supplements.
Protein Supplementation Rational
The basis of protein supplementation is that weightlifters, body builders, and even regular athletes need protein to foster muscle growth and maintenance. Muscles need to be fed a complete protein, especially following exercise. There is an alleged one-hour window of opportunity when muscles are most receptive to nutritional replenishment in the form of amino acids (broken down protein). Following exercise, appetite is suppressed due to increased body temperature and endorphins and therefore a need is created for an easily digestible protein source (http://www.bradventures.com/nutrition/products/protein/completewhey.shtml). Protein supplements are this source and are used by athletes to repair and build muscles following tough workouts. It does so by supplying the essential amino acids that are a precursor to muscle building (http://www.bodybuildingforyou.com/protein/whey-protein-supplements.htm). If the body is deficient in protein it compensates by catabolizing (breaking down) muscle tissue to obtain the amino acids it needs (http://www.bradventures.com/nutrition/products/protein/completewhey.shtml). This lack of protein (which leads to catabolism) may obstruct athletic goals (http://www.gnc.com/category.aspx?id=71&lang=en). The resulting breakdown of healthy cells (the catabolism due to insufficient protein) leads to an elevated injury risk, slowed recovery time, increased feelings of lethargy, and poor athletic performance (http://www.keysupplements.com). The protein supplement supplies essential amino acids that play a vital role in all of the body’s functions, particularly building and repairing muscle (www.pillfreevitamins.com/buildmuscle.htm). It is possible to try to ingest sufficient amounts of protein from whole foods. Doing so may lead to an increased intake of fat and calories in order to ingest as many grams of protein as are available in a more easily prepared and healthier protein supplement (http://www.thepumpingstation.com/pyramidpower.html). The recommended daily intake of protein is as high as one gram per pound of lean body weight (http://www.bradventures.com/nutrition/products/protein/completewhey.shtml).
Protein Supplement Claims
The rational behind protein supplementation involves avoiding a catabolic state that is induced by inadequate amounts of protein (especially following training). However, the information found on these internet sites (supplement and bodybuilding advice sites) goes beyond this simple rational to make claims about what supplementation can do. These benefits includes such things as speeding muscle recovery after workout, helping access and burn body fat, promoting stable blood sugar levels, and enhancing immune system function and stress tolerance (http://www.bradventures.com/nutrition/products/protein/completewhey.shtml). These supposed benefits are of interest for further investigation but are not within the scope of this paper. One claim observed consistently in the majority of internet information on protein supplementation is that protein will increase lean muscle mass (http://www.bradventures.com/nutrition/products/protein/completewhey.shtml), help support muscle growth, help increase strength (http://www.muscletech.com/PRODUCTS/NITRO-Tech/MAIN/NITRO_Tech.shtml), and improve muscle performance (http://www.keysupplements.com). These claims will be evaluated by reviewing the scientific literature that focuses on protein supplementation and its effect on increasing mass and improving strength. A final note of importance is that only one of the internet information sources made mention of potential side effects, to which it stated that supplementation placed no strain on the liver or kidneys (http://www.bradventures.com/nutrition/products/protein/completewhey.shtml). Other sites had made no mention or stated there were no side effects.
Who is making these claims?
Prior to the evaluation of scientific literature on this topic, the sources of the aforementioned information on the claims and rational of protein supplementation must be evaluated. The sources could be classified in two ways: bodybuilding and fitness advice sites and supplement product sites. Product sites clearly have a vested interest in promoting protein supplementation. The bodybuilding advice and magazine sites appear to have a more unbiased perspective in evaluating protein. However, many of these sites have links to product sites if they are not selling protein supplements themselves. There is inherent self-interest from which these sites are evaluating protein supplements.
Scientific Literature Review
1. Empirical Studies
To critically evaluate the aforementioned claims about protein supplementation, a brief review of several empirical studies and review articles follows. While not all of the articles are in total agreement with one another, this overview of empirical studies and review articles should present a more scientific and critical perspective of protein supplementation.
Lemon, Tarnopolsky, MacDougall, and Atkinson (1992) examine the protein requirements for strength athletes in the initial stages of intense resistance training and if a high protein intake would result in significantly greater gains in muscle mass or strength gains than would a low protein intake. The experimenters utilized a double-blinded study of 12 individuals who acted as their own control. These novice weightlifters (used because effects could be more easily seen than in current bodybuilders) underwent two different one month periods of dietary supplementation of either 1.5g/kg of carbohydrate or 1.5g/kg protein (gram per kilogram body weight). The subjects completed a 6 days/wk bodybuilding program supervised by professional body builders. The effects were measured both before and after the training periods and included lean body mass, midarm and midthigh circumferences, CAT scans of midarm and midthigh, NBAL, one rep max (1RM) contraction strength for bench press and leg squat, peak twitch tension, maximal isometric contraction force, and posttetanic of forearm flexors as well as percent motor unit activation and biceps muscle nitrogen concentration (1992).
The results of this experiment found no dietary treatment effects on body weight, percent body fat, body density, urinary creatine excretion, or bicep muscle nitrogen concentration. Although body density, midthigh area, and leg strength measures showed slightly greater increases with protein supplementation, the differences between the two groups were not statistically significant. However, it was concluded that there is an increased need for protein intake in novice bodybuilding in the early stages of training, but at some point above 1.5-1.8g/kg x day the relationship becomes curvilinear and excess protein has no effect. The study concludes that despite the slightly increased need in protein, there are no measurable gains (strength or mass) from increasing protein intake from 1.35 to 2.62 g/kg/day (Lemon, Tarnopolsky, MacDougall, & Atkinson 1992).
Another empirical study examined the effects of a post-exercise recovery supplement. This study compared a carbohydrate only control supplement with a supplement containing whey protein, amino acids, creatine, and carbohydrate and its effect on gains in fat free mass, muscle strength and endurance, and anaerobic performance (Chromiak, Smedley, Carpenter, Brown, Koh, Lamberth, Joe, Abadie, & Altorfer 2004). This study utilized a double-blinded, randomized design with 41 male participants between 18 and 35 years of age. Twenty participants in the control group (receiving carbohydrate post-exercise supplement) and 21 participants in the treatment group (receiving the carbohydrate, creatine, protein, and amino acid post-exercise supplement) participated in a 10 week, 4 days/wk strength training program. Both groups were tested before and after this period for body composition, one rep max strength and endurance for bench press and leg press, and anaerobic performance. Of the subjects, 33 completed the study (18 in treatment group, 15 in control group) (2004).
The results found no greater improvements in body composition, muscle strength or endurance, and aerobic performance for the creatine, protein, amino acid, and carbohydrate supplementation group compared with the control (carbohydrate only) group. There was a trend toward increased fat free mass (FFM) in the treatment group (5% vs. 2.2% increase). However, the article states “it is likely that a significant portion of any increase in FFM that occurs with a supplement containing creatine, protein, amino acids and carbohydrate is due to the creatine. Studies have reported increases in FFM of similar magnitude with strength training and creatine” (Chromiak, Smedley, Carpenter, Brown, Koh, Lamberth, Joe, Abadie, & Altorfer 2004). Thus, this article corroborated the previously mentioned study by concluding that a 10-week strength training program with post-exercise supplementation containing whey protein, amino acids, creatine, and carbohydrate does not significantly affect body weight, percentage body fat, muscle strength and endurance, or anaerobic performance more than a carbohydrate only supplement does (2004).
A third empirical study evaluated body composition and exercise performance effects of essential amino acid supplementation on untrained women over a six-week period (Antonio, Sanders, Ehler, Uelmen, Raether, & Stout 2000). This study was double-blinded and placebo controlled. The subjects, 21 females 18-35 years of age, in good health and not currently taking a dietary supplement, were randomly assigned to a control/placebo group or a treatment/supplement group that received 18.6g of essential amino acids daily, ingested before and after exercise, or in the mornings on non-exercise days. The subjects trained three days per week in aerobics and weight training (split-routine, multiple-set) (2000). The effects were measured by performance in a 12-rep max supine free weight bench press, treadmill to exhaustion, and body composition as assessed via body scans using dual-energy x-ray absorptiometry (2000).
Antonio et al. (2000) found no baseline differences between groups in body weight, lean body mass, fat mass or total weight lifted. However, treadmill time to exhaustion increased significantly in the treatment group. While this is an important finding in its own right, the results of this study further the scientific evidence that supplementation of protein (amino acid form) did not significantly increase lean body mass or strength (2000).
Shifting the focus from empirical studies, Nissen and Sharp (2003) offer a broader approach; they focus on the larger realm of dietary supplements (including protein) and their effects on lean mass and strength via Meta analysis. This Meta analysis focused on data sources meeting several criteria. Studies published in English that included full body resistance training at least twice per week, utilized placebo groups, lasted at least three weeks, and made an estimate of lean body mass were the only studies included in their analysis (Nissen & Sharp 2003). The Meta analysis focused solely on placebo controlled, randomized studies that were published in peer reviewed journals and met these conditions (2003).
Nissen and Sharp (2003) conclude that only creatine and HMB augment lean tissue increases produced by resistance exercise. More specifically, it was found that protein supplementation had no effect on strength or lean mass. Nissen and Sharp’s focus on the larger body of empirical studies of dietary supplements that are utilized to increase body mass and strength found that protein was not a supplement that has been proven to significantly increase either (2003).
3. Review Articles
The previous articles have begun to establish that protein supplementation is not beneficial in terms of lean mass gain or strength increases. The reasons for this are not made explicit in the Meta analysis or empirical studies. Lawrence and Kirby (2002) evaluate the necessity of protein supplementation and conclude that protein requirements of athletes are met by the standard American diet (Lawrence & Kirby 2002). They continue to explain by exposing that most supplements fall extremely short of the protein contained in food such as 3.5 ounces of chicken (30.9 grams of protein) or 3 ounces of light tuna (25.1 grams of protein (2002). Most protein supplements do not offer this amount of protein. Lawrence and Kirby (2002) contend that most athletes ingest sufficient amounts of protein in their habitual diet. Finally, Lawrence and Kirby present an empirical study by Rasch and Pierson to exemplify the lack of scientific evidence that increasing protein intake will improve metabolic efficiency and increase muscle mass. In this reviewed empirical study both the placebo and treatment group showed gains in strength; no significant difference between these two groups was noted (2002).
A final review article presents one additional position regarding the ineffectiveness of supplementation. Tipton and Wolfe (2004) establish a few ideas behind the finding that protein supplementation does not confer increases in lean mass or strength. In their review article, Tipton and Wolfe (2004) seek to establish the idea that protein requirement is defined as the “minimum protein intake that satisfies metabolic demands and which maintains body mass” (Tipton & Wolfe 2004). Protein ingestion for athletes or those who seek to build muscle must be defined as the amount of protein that increases strength or lean body mass (more than satisfies daily requirements). Yet there is still disagreement as to the impact of exercise on protein requirements (2004). In fact, this article suggests that there is evidence that habitual exercise does not increase protein needs (2004). Studies that this article reviewed offer no clear evidence that different amounts of protein ingestion coupled with resistance exercise lead to increased protein needs; it is suggested that energy intake (total caloric intake) is more important than protein intake; strength and mass gains can be made with relatively little protein so long as there is sufficient energy available (2004).
Conclusions and Recommendations
In light of the three previous empirical studies, one meta-analysis, and two review articles, protein supplementation must be approached with skepticism and doubt. In recognition that the benefits of protein are posited by those who are manufacturing or selling the product, this empirical analysis and scientific literature review presents an unbiased, unequivocal view of protein supplementation as most likely unnecessary and certainly unproven. While Tipton and Wolfe (2004) doubt even the basis that athletes or weight lifters might need more protein, Lawrence and Kirby (2002) suggest that the habitual diet of athletes more than contributes necessary protein. Additionally, all three empirical studies found similar results. Protein supplementation (no matter the amount of protein supplemented) has no significant effects in increasing mass or strength in men (Chromiak, Smedley, Carpenter, Brown, Koh, Lamberth, Joe, Abadie, & Altorfer 2004) or women (Antonio, Sanders, Ehler, Uelmen, Raether, & Stout 2000). The paucity of empirical studies that support protein supplementation as a way to increase mass and strength further diminishes any potential desire to supplement. The expense of protein supplements and their unproven effectiveness should be reason enough to avoid buying into this unproven product. As mentioned earlier, protein requirements for athletes and weight trainers are usually already met by habitual diet and perhaps the best way to increase mass or strength is to increase total energy intake (Tipton & Wolfe 2004). Thus, the best way to increase body mass and muscle strength is to continue resistance training and increase total caloric intake. Protein supplements are expensive, unproven, and only supported by manufacturers and those who sell them.
Antonio, J., Sanders, M.S., Ehler, L.A., Uelmen, J., Raether, J.B., & Stout, J.R. (2000). Effects of exercise training and amino-acid supplementation on body composition and physical performance in untrained women. Nutrition, 16, 1043-1046.
Chromiak, J.A., Smedley, B., Carpenter, W. Brown, R., Koh, Y.S., Lamberth, J.G., Joe, L.A., Abadie, B.R., & Altorfer, G. (2004). Effect of a 10-week strength training program and recovery drink on body composition, muscular strength and endurance, and anaerobic power and capacity. Nutrition, 20, 420-427.
Lawrence, M.E., & Kirby, D.F. (2002). Nutrition and Sports Supplements. Journal of Clinical Gastroenterology, 35, 299-306.
Lemon, P.W.R., Tarnopolsky, M.A., MacDougall, J.D., & Atkinson, S.A. (1992). Protein requirements and muscle mass/strength changes during intensive training in novice bodybuilders. Journal of Applied Physiology, 73, 767-775.
Nissen, S.L., & Sharp, R.L. (2003). Effect of dietary supplements on lean mass and strength gains with resistance exercise: a meta-analysis. Journal of Applied Physiology, 94, 651-659.
Tipton, K.D., & Wolfe, R. R. (2004). Protein and amino acids for athletes. Journal of Sports Sciences, 22, 65-80.
The Health Psychology Home Page is
produced and maintained by David Schlundt, PhD.
Vanderbilt Homepage | Introduction to Vanderbilt | Admissions | Colleges & Schools | Research Centers | News & Media Information | People at Vanderbilt | Libraries |Vanderbilt Register | Medical Center
|Return to the Health Psychology Home Page|
|Send E-mail comments or questions to Dr. Schlundt|