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Original Research

Protein Supplement Users Among High School Athletes Have Misconceptions About Effectiveness

Duellman, Margaret C1; Lukaszuk, Judith M1; Prawitz, Aimee D1; Brandenburg, Jason P2

Author Information
Journal of Strength and Conditioning Research: July 2008 - Volume 22 - Issue 4 - p 1124-1129
doi: 10.1519/JSC.0b013e31817394b9
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Protein supplements commonly are ingested by athletes to improve strength, agility, and speed. During resistance training, protein intake plays a direct role in regulating the synthesis of muscle protein (2,5,15); a mere 6 g of essential amino acids ingested immediately before or after resistance training promotes muscle growth (3,16). While athletes require a higher amount of protein (g·kg−1 body weight) than nonathletes do to support protein synthesis, they do not necessarily need to consume protein from supplemental sources (1). To date, no studies have shown an advantage of ingesting protein supplements over natural, protein-containing foods; therefore, dietary sources of protein may be just as effective as protein supplemental sources in the regulation of muscle protein synthesis.

Misconceptions regarding protein supplement effectiveness may originate from athletes' nutrition information sources. A survey questionnaire queried high school football players about sources of information and measured protein supplement misconceptions by using scores on a Protein Supplement Misconceptions Index. Sixty-one high school football players participated in the study; 39 were protein supplementers, and 22 were non-protein supplementers. There was a significant difference between supplementers' and nonsupplementers' index scores (t = -3.4, p = 0.001), indicating that supplementers had a greater level of misconception regarding protein supplements than nonsupplementers did. Bonferroni post hoc procedures used with individual index items revealed that supplementers were more likely than nonsupplementers to agree that “athletes should take protein supplements” (p = 0.001) and needed them “to gain as much muscle as possible” (p < 0.001). Greater misconceptions for supplementers may have resulted from the sources chosen for information and advice. Since coaches, parents, and friends were the primary sources of advice about protein supplements for protein supplementers, it would be valuable to provide nutrition education to these groups concurrently with educating young athletes to dispel ongoing misconceptions regarding the need for and effectiveness of protein supplements.

Protein supplements are among the most commonly used ergogenic aids (11). Protein or other nutritional supplements are ingested by athletes with the anticipation that strength, agility, speed, power, and muscle gain will increase (6). Such misconceptions may originate from athletes' sources of information, as previous studies (4,6,7,12) have shown that athletes' nutrition information sources may be less than scientific. O'Dea and Rawstorne (12) reported that adolescent boys received weight gain information primarily from parents, friends, and coaches. Burns et al. (4) noted that many athletes were unable to identify a professional qualified to provide nutrition information. Among Division I collegiate athletes, 27% were unsure whether a registered dietitian was on site, and only 14% considered a registered dietitian to be a primary source of nutrition information (4).

Given the sources that athletes are consulting for nutrition information, it is unlikely that they are obtaining research-based nutrition knowledge. For example, when 328 college athletes were asked to identify the correct percentage of total calories needed from protein, fat, and carbohydrates, only 3%, 12%, and 30%, respectively, responded correctly (14). Rosenbloom et al. (14) reported that 63% of male athletes knew carbohydrates and fat were the primary energy sources for exercise but that 47% believed protein was the main energy source for muscle and that 35% believed protein supplements were necessary to improve athletic performance.

In most instances, the use of protein supplements is not harmful; however, some athletes believe that protein supplements are needed to help them excel in athletics (14). While dietary protein intake is important to augment muscle protein synthesis following resistance exercise, the use of protein supplements is not warranted. No studies have shown an advantage of protein supplements over natural, protein-containing foods. Most adolescents do not have a strong background in nutrition (7,14) and thus are unable to make informed decisions when considering the use of protein supplements.

To date, no studies have focused solely on the use of protein supplements among high school athletes. The focus of the current study was to determine whether male high school football players who chose to take protein supplements (i.e., protein supplementers) had more misconceptions regarding their effectiveness than non-protein supplementers did. The findings of this study can provide direction for nutrition intervention with this population.


Experimental Approach to the Problem

A survey questionnaire was designed to identify misconceptions regarding the use of protein supplements and to measure the level of misconception among participants. The questionnaire was divided into 2 sections. Section 1 contained 6 open-ended items examining the sources of information and advice, the perceived risks and benefits of protein supplements, and the ability to identify food sources of protein. Section 2 was an index comprising 8 items to measure misconceptions about protein supplements. Response choices were presented in a 4-point Likert-type format (1, strongly agree; 4, strongly disagree), with 1 representing the greatest misconception and 4 representing the least misconception. One statement, “Eating large amounts of protein is harmful to my health,” was reverse-coded to better reflect the level of misconceptions in the computation of total scores. Responses from all statements were summed to produce a Protein Supplement Misconception Index score for each participant. The possible range for scores was 8 to 32, with lower scores representing more misconceptions.

Protein supplementers were defined for this study as subjects who were currently or had previously ingested a commercially formulated product designed for the purpose of obtaining high levels of protein (≥15 g·serving−1) for ergogenic benefits. Non-protein supplementers were individuals who had never ingested such a product.


A high school football team in a small Midwestern town was selected to participate in the study. Prior to data collection, approval for the study was granted by the institutional review board at Northern Illinois University, the high school and athletic department administration, and the football coaching staff. Sixty-one athletes returned necessary assent and parental consent forms. The mean age for participants was 15.5 ± 1.14 years. Most (n = 58) were white; 17 were freshman; 19 were sophomores; 13 were juniors; and 12 were seniors.

Pilot Study

The index was piloted for face validity with 10 high school students participating in an after-school resistance training program who returned signed assent and parental consent forms. Their recommendations were incorporated into the final draft to improve readability and clarity.

Statistical Analyses

Open-ended responses from Section 1 were coded and categorized. Participants were divided into 2 groups based on protein supplement usage (i.e., protein supplementers and non-protein supplementers). Responses to individual items in the Protein Supplement Misconception Index scores were summed to produce index scores for both protein supplementers and non-protein supplementers. Cronbach's α tested for internal consistency of the 8 items in the index. An independent sample t-test compared the mean index scores of protein supplementers and non-protein supplementers to determine difference in levels of misconception. A Bonferroni post hoc test using a corrected α value of 0.006 identified differences in responses to individual index items of protein supplementers and non-protein supplementers. Data were analyzed by using SPSS for Windows, version 14.0 (SPSS, Inc., Chicago, IL).


Of the 61 participants, 39 reported the use of protein supplements at some time; of these, 17 were current supplement users. Current protein supplementers consumed protein supplements an average of 6 times per week. The remaining 22 participants had never used protein supplements. Responses from open-ended statements are summarized for protein supplementers and non-protein supplementers in Table 1.

Table 1
Table 1:
Participant Responses to Open-ended Questions.

Most (n = 21) of the 39 protein supplementers reported they had received protein supplement use information from coaches; other information sources for protein supplementers included friends (n = 8) and media (n = 7). Only 7 non-protein supplementers reported coaches as an information source, and 5 reported a health class as their source of information. Nearly half (n = 17) of protein supplementers and the majority of non-protein supplementers responded that no one had advised them to take protein supplements. For protein supplementers who were advised to take protein supplements, the sources of advice were coaches (n = 11), friends (n = 6), and parents (n = 4).

The range of possible scores for the Protein Supplement Misconception Index was 8 to 32, with lower scores indicating greater misconception. The scores for participants in this study ranged from 9 to 27. Internal reliability was tested by using Cronbach's α, with at least 0.70 indicating an acceptable level of internal consistency. Cronbach's α for the 8 items in the index was 0.713. Mean scores were 18.8 ± 2.9 for protein supplementers and 21.5 ± 2.9 for non-protein supplementers. A t-test detected a significant difference between mean scores for the 2 groups (t = −3.4, p = 0.001), indicating that protein supplementers had more misconceptions about protein supplement use than non-protein supplementers did.

Bonferroni post hoc tests identified differences between groups on 2 individual items making up the Protein Supplement Misconception Index. For the statements, “Athletes should take protein supplements” and “To gain as much muscle as possible, I need to take protein supplements,” protein supplementers were more likely than non-protein supplementers to have misconceptions. Table 2 shows a list of items making up the Protein Supplement Misconception Index.

Table 2
Table 2:
Items making up the Protein Supplement Misconception Index.


The results supported the hypothesis that protein supplementers would have more misconceptions regarding protein supplement use than non-protein supplementers would. The results were as expected, as a larger percentage of protein supplementers than non-protein supplementers reported having received information and advice about protein supplement use from less scientific nutrition information sources, including coaches, friends, and the media. Furthermore, 21 protein supplementers reported that coaches, parents, or friends advised them to take protein supplements, whereas only 6 non-protein supplementers reported having been advised by anyone to take supplements. Coaches, parents, and friends of high school athletes are not likely to be qualified to give research-based nutrition guidance. Athletes' reliance on nonscientific nutrition information sources also has been reported by other researchers (4,6,7,12).

Mean responses for individual index items were compared for protein supplementers and non-protein supplementers. Protein supplementers were more likely than non-protein supplementers to hold the misconceptions that athletes should take protein supplements and, specifically, that they should take them to gain as much muscle as possible. The American College of Sports Medicine, American Dietetic Association, and Dietitians of Canada have concluded that although athletes have a slightly higher protein requirement need than nonathletes, the vast majority of them consume more dietary protein than required (1). Provided that caloric intake is sufficient to maintain body weight, athletes do not need to fortify their diets with additional protein supplements (1,9,13). Lemon (9) suggested that there is a limit to the amount of protein that can be used effectively to regulate muscle protein synthesis. An appropriate and safe amount of protein required daily to stimulate muscle protein synthesis in a strength athlete is between 1.6 and 1.7 g of protein per kg of body weight (1,9,13). For an athlete weighing 200 pounds, or 91 kg, this would be the daily dietary equivalent of 4 cups of milk; 2 eggs; 4 3-ounce servings of beef, poultry, or fish; 1 cup of yogurt; and 1 or 2 1-ounce servings of cheese.

While the long-term consequences of high protein intake are still being explored, possible risks include dehydration, gout, urinary calcium loss, renal damage, diarrhea, bloating, atherosclerosis, and colon cancer (8,17). Over half of the protein supplementers believed there were no risks associated with protein supplement use, compared with only 4 non-protein supplementers who held this belief. The current study verified what has been reported by others (7,14), that most adolescents do not have completely accurate or extensive nutrition knowledge. This finding, in combination with the reported use of less than scientific information sources, confirmed that young athletes are not equipped to make informed decisions when considering the use of protein supplements.

The majority of football players in this study reported having used protein supplements. This finding emphasizes the need for nutrition education for young athletes. Since high school athletes who use protein supplements have misconceptions about the effectiveness of such products, dietitians specializing in sports nutrition should provide nutrition education at the beginning of junior high school to help disseminate correct information before athletes reach high school.

Athletes reported that coaches, parents, and friends provided them with protein supplement use information and advice; therefore, it would be valuable to provide nutrition education to these groups concurrently with education to young athletes. Although most protein supplement products are not harmful, it is important to stress that high-quality protein sources are available through food. Most athletes in the study appeared to have accurate beliefs about which foods contain protein, and they can learn that by adjusting their diets to include slightly more of these food sources, they can consume enough protein through their diet to promote muscle growth following resistance training. Emphasis should be placed on the concept that the use of expensive protein supplements is unnecessary.

This study was limited in its generalizability by the small sample size and the homogeneity of the sample. Furthermore, only football players were included in the study, and this group likely had muscle growth and strength goals that differed from those of athletes in other sports. However, the goal of this study was to determine the level of misconceptions regarding protein supplement use; this group of football players represented athletes who likely were required to participate in resistance training exercises and thus provided a sample of athletes with strength goals. Further research with a larger sample of high school athletes in various sports is needed to determine the level of misconceptions about protein supplement use by athletes involved in different sports.

Practical Applications

Coaches and their coaching staff need access to appropriate information about protein and protein supplement use, since many athletes respect them and look to them for nutrition advice. Nutrition professionals, such as registered dietitians with specialization in sports nutrition, can offer research-based nutrition education materials to coaches and young athletes to help dispel ongoing misconceptions about protein supplements. Nutritional guidance should include discussions of the following: guidelines on how to incorporate low-fat, high-protein food choices, such as cheese made with skim milk, low-fat yogurt, soy products, skim milk, chicken, turkey, and fish, into the daily intake to meet protein needs without the use of protein supplements; the importance and timeliness of consuming 6 g of essential amino acids before or after resistance training to maximize muscle growth from the workout; high-fat dietary protein sources that should be limited (e.g., red meat, highly processed meats, and whole milk); possible side effects and risks associated with excess protein intake; the importance of other nutrients for athletic performance (i.e., adequate calories, carbohydrates, water, and electrolytes); protein supplementation as an option that is costly and unnecessary; and the avoidance of protein supplements that contain only single amino acids to prevent imbalances in amino acid absorption.


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    sports nutrition; ergogenic aids; resistance training

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