Introduction
Extensive research has been done on soy and whey protein supplementation in conjunction with resistance training. Which protein, soy or whey, has more anabolic effects on the male athlete? This is an important question since nearly half of all male athletes supplement with protein (1).
Some studies suggest soy protein decreases serum testosterone by over 20 percent in men (2, 5, 6). Even minimal amounts of whey protein supplemented after a resistance workout in trained young men showed an increase in muscle protein synthesis (3, 7, 8). It seems clear that whey protein would be a superior choice to a male athlete looking to enhance hypertrophy or strength. A recent study showed, in young men engaging in resistance training, that whey protein was not superior to soy; increases in lean muscle mass may have been from increased protein intake of either type (4,8).
Research Question
Which supplemental protein, soy or whey, is more beneficial for the male athlete that engages in resistance training with a goal of maximum muscle hypertrophy?
Data Sources
SPORTDiscus was searched through EBSCOhost for the terms whey protein + hypertrophy, testosterone levels, and strength training. The same terms were then searched with soy protein. Full-text articles, dated January 2000 to December 2009, were included in this review.
Annotated Bibliography
1.Bailey R, Bloodworth A, McNamee M, Naughton D, Pearce G, Petroczi A. Nutritional supplement use by elite young UK athletes: fallacies of advice regarding efficacy. J Int Soc Sports Nutr. 2008; 5:22.
All people involved with this study were members of the faculty at various universities in Great Britain. The study was performed to determine the reasons behind elite UK athletes’ use of supplements. What were the motives for using these substances? Did a rationale versus practice incongruence exist? The researchers also wanted to further investigate the athlete’s sources of information. Literature read by the athlete to help him/her make their choice was also analyzed.
Both elite male and female athletes participated in the study. The age range of participants was between 12 and 21, with a total of 403 participants. The mean age was approximately 18 years old with a standard deviation of almost two years. The associations for the choice of supplements used and the reason for using the supplements was calculated using Pearson’s chi-squared test. The strength of the symmetric associations was shown by phi association coefficients.
Supplement use was very widespread in the elite athlete population in Britain. The rationale most athletes had for supplementation was clearly performance enhancing, while the researchers believe older adults have seemed to be more health conscious. Further research is needed to say conclusively that most young athletes choose supplements because of performance enhancement benefits rather than health ones.
This study was performed because supplement use appears to be very popular with young athletes for health reasons along with performance enhancing ones. The authors wanted to find the specific rationale for supplementation. This paper was directed at coaches to be able to help athletes make decisions about supplementation. This study directs any coach working with athletes’ nutrition needs to keep in mind that many athletes’ primary motivator is performance enhancement, not health.
2.Goodin S, Shen F, Shih WJ, et al. Clinical and biological activity of soy protein powder supplementation in healthy male volunteers. Cancer Epidemiol Biomarkers Prev. 2007;16:829-833.
There are ten authors, all from various medical schools in New Jersey.
Cancer patients and oncologists would find this useful, and it appeared in a cancer research journal. This study looked at the effects of over-the-counter soy protein supplements. It compared testosterone levels of healthy male volunteers. They found that during four weeks of supplementation with soy protein, serum testosterone levels decreased. The study looked at the effects of using soy as treatment for patients with prostate cancer. Another study I looked at also showed that supplementation with soy protein caused a significant drop in serum testosterone levels (5).
Maximizing testosterone levels is essential for any male with a goal of muscle hypertrophy. Therefore, any athlete with this goal must look seriously at supplementation with soy protein.
3.Kujbida G, Lyseki P, Manolakos J, Moore D, Phillips S, Tang J. Minimal whey protein with carbohydrate stimulates muscle protein synthesis following resistance exercise in trained young men. Appl Physiol Nutr Metab. 2007; 32: 1132-1138.
The Exercise Metabolism Research Group from the Department of Kinesiology at McMaster University performed this study. McMaster University is located in Hamilton, Canada. The target audience is young men who are experienced with resistance training.
In this study the authors acknowledged whey protein is a supplement used by athletes with a goal of muscle hypertrophy. Direct evidence for whey protein’s efficacy for stimulating muscle protein synthesis is not sufficient. The researchers wanted to demonstrate the impact of ingesting whey protein on skeletal muscle protein turnover in the period following resistance training.
Eight healthy young men with prior resistance training experience participated in the study. Subjects performed the same resistance training exercises with 4 sets of 8 to 10 repetitions using approximately 80% of their one rep max. The effects on muscle protein synthesis were examined with a carbohydrate only supplement, a whey only supplement and a combination of carbohydrate and whey protein supplement. All three independent variables (the three supplements) effects were tested on the dependent variable, the muscle protein synthesis. The study used a two-way ANOVA, which allows for very complete research.
The study showed that the whey only group had greater muscle protein synthesis than the carbohydrate only group. The whey and carbohydrate group had a greater muscle protein synthesis than the whey only group. The study showed whey protein supplementation post resistance training in trained young men would help support a positive net protein balance, over time leading to muscle hypertrophy.
4. Burke D, Burke N, Candow DG, Smith-Palmer T. Effect of whey and soy protein supplementation combined with resistance training in young adults. Int J Sport Nutr Exerc Metab. 2006;16: 233-244.
The Department of Human Kinetics at St. Francis Xavier University in Nova Scotia, Canada, employs Natalie and Darren Burke; Smith-Palmer is with St. Francis Xavier University’s Department of Chemistry. Candow is with Laurentian University’s School of Human Kinetics.
The study was in the International Journal of Sport Nutrition and Exercise Metabolism, aimed primarily at coaches and people in the sports nutrition field. The study wanted to find out if whey and soy protein supplementation, along with resistance training, increased muscle mass and strength in young adults.
There were 27 subjects, 18 female and 9 male. These people volunteered for the study through newspaper advertisement. They were tested prior to the “initial testing” so to make sure the subjects were free from other ergogenic aids, eliminating any biased effects from other supplementation.
There were several instruments used. To record any resistance training improvement, each subject first participated in three supervised training sessions, three times per week, for three weeks. They then began a six week training program taking either protein or placebo supplements. All training sessions were supervised. The lean tissue mass was assessed by a DEXA scan. This was completed at the beginning of the study, as well as the end of the six-week program. The same technician analyzed all DEXA scans.
To assess the muscle strength, a one-repetition maximum squat and bench press were observed. These were chosen because they involve the major muscle groups in the upper and lower body. The subjects were also asked to give a urinary analysis for 3-methylhistidine. A dietary assessment was also conducted, by requiring each subject to record all food items and portions for three designated days. The Food Processor version 7.8 analysis program then provided energy consumption, as well as energy obtained from carbohydrates, fats, and proteins.
This was a true experimental design. They tried to maintain control and minimize threats to validity. The subjects were random because they were from a newspaper advertisement. They tried to evenly distribute and compare the subjects based on age and body mass. Each subject consumed the three equal doses of either whey or soy protein, or a placebo. These amounts were based on equations that involved their body mass. The equation for the whey protein was 1.2g/kg body mass whey protein + .3 g/kg body mass sucrose powder. The same equation was used for soy protein, as well as the placebo. Subjects consumed the supplements about 30 minutes before and after each training session. The supplements were mixed with sucrose to ensure that the protein and placebo were similar in energy content, taste, texture, and appearance. Pre- and Post-Tests were administered throughout the program.
A 3 (whey vs. soy vs. placebo) x 2(pre vs. post) ANOVA with repeated measures on the second factor was used to determine if there was a difference between the protein and placebo groups over time for the dependent variables mass, strength etc. Whey protein was not superior to soy; increases in lean muscle mass may have been from increased protein of either type. This study showed that soy protein may be as beneficial as whey protein for the athlete attempting to achieve muscle hypertrophy.
5. Hulmi JJ, Ahtiainen JP, Selanne H, et al. Androgen receptors and testosterone in men-Effects of protein ingestion, resistance exercise and fiber type. J Steroid Biochem Mol Biol. 2008; 110: 130-137.
The authors are from The University of Jyvaskyla, in Finland, as well as the Human Performance Laboratory from the Department of Kinesiology, University of Connecticut. The article is from the Journal of Steroid Biochemistry and Molecular Biology, so the audience is anyone involved in endocrinology.
The study was performed to examine the impact of protein consumption on muscle androgen receptors, IGF-1, and circulating testosterone levels. The subjects were 57-72 year old men, and they all performed resistance training. The workouts were five sets of 10 repetitions. The subjects consumed either 15 grams of protein or a placebo before and after the resistance training. Vastus lateralis muscle biopsies were taken one hour prior to resistance training, and 48 hours post resistance training. The group that supplemented with whey protein had increased serum free and total testosterone levels.
Most of the information regarding the impact of whey protein on testosterone levels is found in non-peer-reviewed sources, such as bodybuilding web sites, and are based on opinion, rather than fact. This is important for the male athlete with a goal of hypertrophy to consider because whey has positive anabolic affects of increased testosterone levels, along with the added benefits of whey protein supplementation.
6. Weber KS, Setchell KDR, Stocco DM. Dietary soy-phytoestrogens decrease testosterone levels and prostate weight without altering LH, prostate 5a-reductase or testicular steroidogenic acute regulatory peptide levels in adult male Sprague-Dawley rats. Am J Physiol Endocrinol Metab. 2001; 170: 591-599.
This study was performed by the Neuroscience Center at Brigham Young University in conjunction with Department of Cell Biology and Biochemistry at Texas Tech University and the Clinical Mass Spectrometry Center, Children’s Hospital Medical Center, Cincinnati, Ohio. The study was performed because soy-phytoestrogens have been extensively studied for benefits against hormone-dependent and age dependent diseases. This study was performed to help people with prostate cancer.
Animals were fed a soy rich diet or diet free of soy. Researchers observed a significant decrease in bodyweight and prostate weight in the soy group. There was not a significant reduction in the prostate 5a-reductase enzyme. However loco motor activity was higher in the soy free group. This pertains to my topic because even though body weight was reduced, since loco motor activity was reduced, was the weight loss because of lost muscle mass? Testosterone levels were reduced. This fell in line with the other studies I have read. If soy reduces the production of the anabolic hormone testosterone, is it the best choice for an athlete with the goal of hypertrophy? Probably not.
7. Hartman J, Phillips S, Wilkinson S. Dietary protein to support anabolism with resistance exercise in young men. J Am Coll Nutr.2005; 24: 134S-139S.
This study was performed by the Exercise Metabolism Research group, Department of Kinesiology, McMaster University in Hamilton, Ontario, Canada. The study was performed to evaluate previous findings that resistance training is anabolic and stimulates the process of muscle protein synthesis (mps). The net effect of resistance exercise is to shift net protein balance to a more positive balance. Without post workout feedings net protein balance is negative. Post workout food consumption combined with the resistance exercise work together for a higher net protein balance, which results in muscle hypertrophy.
The researchers looked at how soy protein and whey protein affected muscle protein synthesis, muscle protein breakdown, and net protein balance. The study found that whey protein is more effective in stimulating amino acid uptake along with net protein deposition in muscles after resistance training than soy protein. Subjects trained for 12 weeks, five times a week, with weights, using the same resistance-training program. The whey group had an average of an eleven percent greater gain in lean body mass than the soy group. This study showed that whey protein supplementation may be very helpful in populations with compromised muscle mass. This is very beneficial information for an athlete to know when deciding between whey and soy.
8. Kujbida G, Moore D, Phillips S, Tang J, Tarnopolsky M. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. J Appl Physiol. 2009; 107:987.
This study was performed by the Department of Pediatrics and Neurology at McMaster University in Ontario Canada in conjunction with the Department of Kinesiology’s Exercise Metabolism Research Group at the same university. The study was designed to compare the acute response of mixed muscle protein synthesis to whey, soy or casein protein at rest and post resistance training in young men.
Subjects were divided into three groups, each containing six subjects. One group supplemented with whey, one with soy, and one with casein. Each group performed a bout of unilateral leg resistance exercise followed by consumption of 10 grams of whey, soy or casein protein. Whey protein resulted in the largest increase of blood essential amino acid, branch chained amino acid and leucine concentrations than soy or casein. Both soy and whey protein act rapidly but whey protein resulted in 18% greater muscle protein than soy protein at rest, and 31% greater following resistance training. This is very important for any young man with a goal of muscle hypertrophy to be aware of. This study was intended for people in the sports nutrition and physiology field.
9. Burke DG, Chilibeck PD, Davison KS. The effect of whey protein supplementation with and without creatine monohydrate combined with resistance training on lean tissue mass and muscle strength. Int J Sport utr Exerc Metab. 2001; 11 (3): 349-364.
This study examined the effects of whey protein and whey combined with creatine monohydrate on strength and muscle hypertrophy. Strength was measured by one rep max in the bench press, squat and leg extension-- all reliable, accurate ways to measure and collect data. Lean body mass was measured by DEXA scan. Exclusion and inclusion criteria where provided. All males were ages 18-30 with no prior use of anabolic steroids and had gone at least six weeks without creatine use. Subjects were divided into three groups, and received treatments of whey protein, whey protein with creatine monohydrate, or a placebo. All groups followed an identical systemized resistance-training program, with identical sets, reps, and levels of intensity. Initial pretest measurements were done using DEXA scan the day supplementation and resistance training began. Posttest assessments were done after 12 weeks of resistance training/supplementation. Following the 12-week intervention, cross-sectional muscle area increased as a result of hypertrophy. Gains in strength resulted from increased muscle size, rather than neuromuscular adaptations.
All groups experienced an increase in every category following resistance trainings, the smallest effects being observed in the placebo group. The whey only group experienced greater gains than the placebo group in improvements in knee extension peak torque and lean muscle tissue than males that only engaged in resistance training. The men that supplemented with whey and creatine had the greatest increases in lean tissue and their bench press strength improved. Gains in knee extension torque were similar to the whey only group. Whey protein supplementation causes greater hypertrophy in subjects that weight train, than subjects that only weight train without supplementation. Strength gains allow an athlete to work out with heavier weights, which will directly lead to muscle hypertrophy.
10. Elia D, Stadler K, Horvath V, Jakus J. Effect of soy-and whey protein-isolate supplemented diet on the redox parameters of trained mice. Eur J Nutr. 2006;45:259-266.
Some clinical trials have shown the effectiveness of using whey and soy protein in the treatment of diseases. Both types of proteins have anti-oxidant properties. This sparked members of the faculty at the Hungarian Academy of the Sciences in Budapest, Hungary, to perform a study that investigated the effect of whey and protein supplementation on antioxidant effects and lean body weight in swimming trained and non trained animals. This study was intended for nutritionists.
Whey protein was shown to be able to help combat oxidative stress, regardless of training. Soy protein was only effective in treating oxidative stress in non-trained animals. The study showed that whey protein might allow for athletes to train at a higher intensity for a longer period of time. This is beneficial for athletes and nutritionists to know. The longer and harder an athlete can train, the easier a goal of increased muscle mass can be obtained, assuming these results apply to human beings.
- Hartman JW, Tang JE, Wilkinson SB, et al. Consumption of fat-free fluid milk after resistance exercise promotes greater lean mass accretion than does consumption of soy or carbohydrate in young, novice, male weightlifters. Am J Clin Nutr. 2007;86: 373-381.
The study intended to determine the long-term effects of whey and soy protein consumption on lean mass induced from training. Fifty-six healthy young men were used for this study; they resistance-trained five days per week for 12 weeks, on a split body routine. Subjects were divided into three groups. Each group consumed their protein directly after training, and then one hour later. The first group consumed whey protein, the other group consumed soymilk protein, and the third group consumed a mixture of both. Each group consumed approximately 20 grams of their given protein immediately after training, as well as one hour after training.
Muscle fiber size, body composition and strength were measured before and after training for 12 weeks. Strength increased in all groups, and no major differences between the groups were seen. Type II muscle fiber size increased in all groups, with the most seen in the whey protein group. The greatest overall amount of muscle hypertrophy took place with the whey group. The study concluded that post-exercise consumption of whey protein leads to the greatest gains in lean muscle mass in novice weightlifters.
This study was directed at clinical nutritionists. The authors are from the Department of Kinesiology at McMaster University in Ontario, Canada. I think further investigation needs to be done on strength gains with the two types of proteins. High testosterone levels are usually associated with high strength levels. It is interesting that this study doesn’t show any differences even though we have seen that soy protein supplementation significantly lowers testosterone levels.
- 12. Kerksickio CM, Rasmussen CJ, Lancaster SL, et al. The Effects of Protein and Amino Acid Supplementation on Performance and Training Adaptations During Ten Weeks of Resistance Training. J Strength Cond Res. 2006; 643-653.
The Department of Health, Human Performance and Recreation at Baylor University in Waco, Texas, did the study. The study was designed to examine the effects of whey protein supplementation on strength, muscular endurance, body composition, and anaerobic threshold during ten weeks of weight training. Thirty-six resistance-trained males between the ages of 23 and 39 followed a four-day per week, split body part, routine resistance training program for ten weeks. These men were randomly grouped into three groups. The first group received a placebo, group two got 40 grams a day of whey protein, and group three received 40 grams a day of whey protein in addition to three grams a day of branched chain amino acids, plus five grams of glutamine per day. At the beginning of the program, middle, and end, they were tested for blood fasting samples, body composition using a DEXA scan, a one-rep max in the bench and leg press, 80 percent of their one-rep max repetition until failure on the bench and leg press, and a Wingate anaerobic capacity test.
No changes were noted in all groups for energy intake, training volume, blood parameters, and anaerobic capacity. The groups with whey protein experienced greater gains in lean mass. Significant increases were noted in maximum bench and leg press for all groups. Athletes and coaches can use this information to help increase muscle mass and improve body composition during resistance exercise.
Clinical Implications
A male athlete with a goal of hypertrophy clearly needs to avoid soy protein. Soy lowers testosterone levels, and testosterone is important, not only for muscle mass, but for recovery from intense resistance training. Whey protein, on the other hand, not only has been shown to aid in increasing hypertrophy and strength, but has no ill effects on testosterone levels. Whey also may have some anti-oxidant properties that would be very beneficial to a hard training athlete. Further research is certainly warranted in this area.
Conclusion
My research has definitely shown me to never recommend soy protein supplementation to a male athlete who wants to increase muscle mass. Even if soy were superior for hypertrophy, it would not be worth significantly lowering serum testosterone levels. Soy did not even exhibit the anti-oxidant properties of whey on trained animals. The choice seems simple.
Future Research
I think future research needs to be done on the anti-oxidant properties of whey protein. Whey may allow an athlete to train harder, longer, and more frequently and might be very beneficial and an ethical alternative to performance enhancement drugs. More research needs to be done to see if whey actually increases testosterone levels, not merely holding levels steady. Whey has only been popular for approximately the last decade, so I am sure plenty more research will occur.