The purpose of my research on protein intake for athletes as MNT was to find out how much protein athletes should consume along with reviewing if protein source, intake timing, and quality make a difference in performance. This topic is not only extremely important and fascinating to myself but is a large issue amongst all athletes. Many athletes follow a specific diet based on their specific sport or regiments. Currently, many endurance athletes are found to be following a low fat, high carbohydrate diet while strength athletes try to consume a high protein diet. Protein source is also a large issue up for discussion with many athletes going vegan and some arguing plant based may not supply the same essential amino acids and recovery needed. Different diets based on protein and protein source are constantly altering and circulating around athletes but nothing has been noted about which may actually be the most effective and safest for athletes. What if some diets are better for endurance athletes versus strength athletes? Some diets don’t explain the risks behind them either such as in a very high protein diet. Some research proposes a high protein diet can lead to renal dysfunction and issues. If we don’t know the proper way to guide athletes on nutrition and know what is optimal for their performance and safety, then further research needs to be done. My purpose is to dig deeper into studies and research to find if protein plays a crucial role in athletic performance and what may be the most advantageous diet. Through my research and studies, I found tests and articles arguing how high protein may or may not offer advantages, plant based is just as effective, and how quality does play a role in athletic performance.
1. Andreato, L. V., Santos, J. F., Esteves, J. V., Panissa, V. L., Julio, U. F., & Franchini, E. (2016). Physiological, Nutritional and Performance Profiles of Brazilian Jiu-Jitsu Athletes. Journal of Human Kinetics, 53, 261–271. http://doi.org/10.1515/hukin-2016-0029
This article analyzes the performance of Brazilian Jiu-Jitsu athletes and the effects of an unbalanced diet of low carbohydrates, high protein intake versus the results of changing the diet. No significant changes in performance were recorded but Jiu-Jitsu athletes had a healthier and more balanced diets with the supplementation of protein.
2. Barron, E., Sokoloff, N. C., Maffazioli, G. D. N., Ackerman, K. E., Woolley, R., Holmes, T. M., … Misra, M. (2016). A High Fiber and Vegetable Protein Diet is Associated with Low Lumbar Bone Mineral Density in Young Oligo-amenorrheic Athletes. Journal of the Academy of Nutrition and Dietetics, 116(3), 481–489. http://doi.org/10.1016/j.jand.2015.10.022
The article addresses bone density of the lumbar spine in young athletes with oligoamenorrhea and if a higher intake of fiber, vegetable protein, and phytic acid are associated with lower BMD scores. It was determined, based on test; a diet with high vegetable protein is associated with a lower bone density. Overconsumption may be linked with energy deficiency and may damage bone but further test need to be done.
3. Bovee, S. E., RD, Silliman, K., PhD, RD, Liotta, D., Azevedo, J., PhD, Linderman, J., PhD. (1997). Effects of a High Fat, High Carbohydrate, and High Protein Diet on Endurance Performance in Trained Cyclists and Untrained Controls. Journal of the American Dietetic Association , Volume 97 , Issue 9 , A73. http://dx.doi.org/10.1016/S0002-8223(97)00574-9
This study analyzed the current low fat, high carbohydrate diet that is recommended for endurance athletes to see if it has more advantages compared to other diets. After reviewing six trained cyclists and five controlled males, the trained cyclists had endurance times that increased by six minutes after consuming a high protein diet and only three minutes after a high fat diet in comparison with a high carbohydrate diet. In conclusion, the low fat, high carbohydrate diet endurance athletes are being told to follow may not offer the most advantages and may experience enhanced performance when consuming a high protein diet.
4. Campbell, B., Kreider, R. B., Ziegenfuss, T., La Bounty, P., Roberts, M., Burke, D., Antonio, J. (2007). International Society of Sports Nutrition position stand: protein and exercise. Journal of the International Society of Sports Nutrition, 4, 8. http://doi.org/10.1186/1550-2783-4-8
This journal stands to review how protein intake can affect and help aid athletes. It concludes that athletes should consume about 1.4-2.0 g/gk/day of protein in order to receive proper muscle repair and protein synthesis during training. It is recommended that the protein come from whole, high quality sources and supplemental protein is a way to intake high quality protein. Protein supplements have been shown to be beneficial and help in recovery and prevent muscle degradation.
5. Hansen, M., Bangsbo, J., Jensen, J., Krause-Jensen, M., Bibby, B. M., Sollie, O., Madsen, K. (2016). Protein intake during training sessions has no effect on performance and recovery during a strenuous training camp for elite cyclists. Journal of the International Society of Sports Nutrition, 13, 9. http://doi.org/10.1186/s12970-016-0120-4
This journal discusses the performance benefits of combined protein with carbohydrates in cyclists. According to the results, the addition of protein to a carbohydrate during cycling and exercise does not improve recovery or performance.
6. Hida, A., Hasegawa, Y., Mekata, Y., Usuda, M., Masuda, Y., Kawano, H., & Kawano, Y. (2012). Effects of Egg White Protein Supplementation on Muscle Strength and Serum Free Amino Acid Concentrations. Nutrients, 4(10), 1504–1517. http://doi.org/10.3390/nu4101504
Over an eight week period, female athletes consumed egg white protein and the study was evaluated to compare the protein intake to carbohydrate prior to exercise based on a one rep max (muscle strength). After the eight weeks of supplementation, it was concluded that the protein intake did result in some changes in metabolites but not in muscle strength.
7. Hoffman, J. R., & Falvo, M. J. (2004). Protein – Which is Best? Journal of Sports Science & Medicine, 3(3), 118–130.
This journal looks deeper into the variety and quality of proteins and determining the pros and cons of each and which may have an upper hand. Research confirms 1.4-1.8 g/kg/day is recommended for strength athletes while 1.2-1.4 g/kg/day is recommended for endurance athletes. Based on this intake and further assessments, it is concluded animal sourced protein is important from infancy to adulthood but vegetable proteins may offer the same benefits with less health risks.
8. Hoffman, J. R., Ratamess, N. A., Kang, J., Falvo, M. J., & Faigenbaum, A. D. (2006). Effect of Protein Intake on Strength, Body Composition and Endocrine Changes in Strength/Power Athletes. Journal of the International Society of Sports Nutrition, 3(2), 12–18. http://doi.org/10.1186/1550-2783-3-2-12
This study analyzes the body composition and strength of 23 collegiate athletes with the intake of protein over a 12-week resistance-training program. The athletes were divided into three groups based upon how much protein they were consuming per day then body composition and strength tests were recorded to compare results. In conclusion, the results did not supply any support for higher protein intakes above RDA for athletes since no improvements were measured.
9. Hoffman, J. R., Ratamess, N. A., Kang, J., Falvo, M. J., & Faigenbaum, A. D. (2007). Effects of Protein Supplementation on Muscular Performance and Resting Hormonal Changes in College Football Players. Journal of Sports Science & Medicine, 6(1), 85–92.
This studies purpose was to analyze hormonal changes in athletes that went through a 12-week training program and supplemented with protein. The placebo group had an average intake of 1.24 g/kg/day and the protein supplemental group had an average intake of 2.00 g/kg/day. After comparing the results, there was no clear difference in body strength, anaerobic power, or lean muscle changes to support the need for a higher protein intake or supplementation.
10. Huang, W.-C., Chang, Y.-C., Chen, Y.-M., Hsu, Y.-J., Huang, C.-C., Kan, N.-W., & Chen, S.-S. (2017). Whey Protein Improves Marathon-Induced Injury and Exercise Performance in Elite Track Runners. International Journal of Medical Sciences, 14(7), 648–654. http://doi.org/10.7150/ijms.19584
This study used three testing points: pre, post, and end test to determine performance with the consumption of whey protein in 12 marathon runners. Results were measured in distance and time of the runners before and after 4 weeks of supplementation. After further review, the distances at times 9 and 12 minutes with supplementation increased therefore quality protein and whey protein could provide enhance performance for aerobic athletes.
11. Jäger, R., Kerksick, C. M., Campbell, B. I., Cribb, P. J., Wells, S. D., Skwiat, T. M., Antonio, J. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14, 20. http://doi.org/10.1186/s12970-017-0177-8
This article reviews protein intake for exercising adults and the amount needed. For average individuals building muscle mass, a range of 1.4-2.0 g/kg/day is plenty, but for high resistance training individuals that may experience hypocaloric periods, an intake of 2.3-3.1 g/kg/day may be needed. This article also investigates how protein intake prior to sleep may increase metabolic rate. After reviewing tests and research, a slight increase in metabolism was found in those that consumed protein prior to sleep and individuals who exercise should consume a minimum of 1.4-20 g/kg/day.
12. Kato, H., Suzuki, K., Bannai, M., & Moore, D. R. (2016). Protein Requirements Are Elevated in Endurance Athletes after Exercise as Determined by the Indicator Amino Acid Oxidation Method. PLoS ONE, 11(6), e0157406. http://doi.org/10.1371/journal.pone.0157406
This study researched how much protein on average endurance athletes require through an amino acid oxidation method. During this test, protein was provided to the body to determine CO2 excretion and phenylalanine oxidation. After analysis, it was concluded that a protein intake higher than the RDA is recommended for endurance athletes due to metabolic demands. This range is from 1.2-1.4 g/kg/day.
13. Lowery, L. M., & Devia, L. (2009). Dietary protein safety and resistance exercise: what do we really know? Journal of the International Society of Sports Nutrition, 6, 3. http://doi.org/10.1186/1550-2783-6-3
This journal addresses and discusses the risks associated with high protein intake such as renal function in athletes and other issues. The article agrees high protein intake could do more harm than good for athletes and these athletes are avoiding the warnings and evidence behind this health risks and issues. Even with agreeing that high protein may cause issues, the authors conclude the research behind whether or not high protein causes risks is not one hundred percent known even after years of conflicting studies.
14. Lowery, L., & Forsythe, C. E. (2006). Protein and Overtraining: Potential Applications for Free-Living Athletes. Journal of the International Society of Sports Nutrition, 3(1), 42–50. http://doi.org/10.1186/1550-2783-3-1-42
This journal reviews the protein intake needed by athletes specifically when overtraining comes in to play and is an issue for recovery. The author records regular endurance athletes are estimated to have an intake of 1.2-1.4 g/kg/day or protein and strength athletes with an intake slightly higher. The author concludes protein supplementation or higher intakes than the RDA should be considered on a case-by-case basis but may show positive effects due to the additional intake of amino acids to help support recovery and goals of certain athletes.
15. Mero, A. A., Huovinen, H., Matintupa, O., Hulmi, J. J., Puurtinen, R., Hohtari, H., & Karila, T. A. (2010). Moderate energy restriction with high protein diet results in healthier outcome in women. Journal of the International Society of Sports Nutrition, 7, 4. http://doi.org/10.1186/1550-2783-7-4
This study was done to compare weight reduction through high protein intake and the effect on performance, body composition, and hormone concentration in non-competing women athletes over four weeks. The studies showed that with about 1.4 g protein/kg/day, weight loss of 0.5 kg per week is recommended in a normal weight female who is physically active. This weight loss with intake of protein may be beneficial in major jumping events.
16. Mori, H. (2014). Effect of timing of protein and carbohydrate intake after resistance exercise on nitrogen balance in trained and untrained young men. Journal of Physiological Anthropology, 33(1), 24. http://doi.org/10.1186/1880-6805-33-24
This study investigates how timing of protein and carbohydrates affects the body after strength and resistance training in males. The body of 20 subjects was assessed by nitrogen balance the final three days of training. Based on the results, the timing of protein and carbohydrate intake did effect the nitrogen balance differently between the untrained and trained subjects.
17. Pasiakos, S. M., Martin, W. F., Sharma, C. S., Pikosky, M. A., Gaine, P. C., Bolster, D. R., Rodriguez, N. R. (2011). Level of dietary protein intake affects glucose turnover in endurance-trained men. Journal of the International Society of Sports Nutrition, 8, 20. http://doi.org/10.1186/1550-2783-8-20
This journal studies how a high-protein diet affects glucose in athletes and adults. This test was done on five endurance athletes comparing glucose turnover rates after consuming 0.8 g/kg/day, 1.8 g/kg/day, or 3.6 g/kg/day of protein. After comparing results, the protein intake with the highest turnover rate was 1.8 g/kg/day.
18. Phillips, S. M. (2014). A Brief Review of Higher Dietary Protein Diets in Weight Loss: A Focus on Athletes. Sports Medicine (Auckland, N.z.), 44(Suppl 2), 149–153. http://doi.org/10.1007/s40279-014-0254-y
Through studies of evaluating optimal protein intake for athletes it was found that protein plays a crucial role in weight loss. The study also argues a higher protein diet may not lead to renal dysfunction. In conclusion, though the RDA of protein may provide enough protein for athletes, having a protein intake of 1.8 g/kg/day and higher may lead to the ability for athletes to preserving lean muscle and allowing more fat loss.
19. Rodriguez, Nancy. (2013). Training Table to the Battlefield: Protein Recommendations for Warfighters. The Journal of Nutrition. http://jn.nutrition.org/content/143/11/1834S.long
This article focuses on the protein needs of warfighters and how the general 1.2-1.8 g/kg/day can be raised. Due to intensive physical conditions and training, protein supplementation is recommended to help in protein synthesis and supply enough energy. Based on the journal’s rationale, consuming 1.5-2.0 g/kg/day of protein will help protect lean muscle mass even with total body mass reduction.
20. Shenoy, S., Dhawan, M., & Singh Sandhu, J. (2016). Four Weeks of Supplementation With Isolated Soy Protein Attenuates Exercise-Induced Muscle Damage and Enhances Muscle Recovery in Well Trained Athletes: A Randomized Trial. Asian Journal of Sports Medicine, 7(3), e33528. http://doi.org/10.5812/asjsm.33528
This study researches the effects of soy protein on muscle damage over a four-week span. The test included forty male cyclists pursuing 30 hours of training a week with half consuming soy protein supplements for four weeks. After comparing pre and post supplemental results, the effective of soy protein was effective indicating plant based supplements can and are effective in muscle repair and recovery.
21. Skinner, Paul, MS, RD, Kopecky, Lisa, RD, Seburg, Sheri, RD, Roth, Tracy, Eich, Jenni, RD, Lewis, Nancy, PhD, RD, FADA. (2001). Development of a Medical Nutrition Therapy Protocol for Female Collegiate Athletes. Journal of the American Dietetic Association , Volume 101 , Issue 8 , 914 – 917. http://dx.doi.org/10.1016/S0002-8223(01)00225-5
This journal analyzes the usefulness of MNT for female collegiate athletes. Many female athletes struggle with amenorrhea, low bone density, and low iron status. Protein intake can help support these issues and it is recommended for teenage athletes to consume 1.2-1.8 g/kg/day and for muscle building athletes to consume 1.4-1.8 g/kg/day of protein. This journal also helps other dietitians in implementing MNT for female athletes and gives them the framework to be successful.
22. Stuart M. Phillips, Stéphanie Chevalier, Heather J. Leidy
Applied Physiology, Nutrition, and Metabolism, 2016, 41:565-572, https://doi.org/10.1139/apnm-2015-0550
This article discusses protein quality, timing of intake, weight management, and the importance of meal planning for athletes. Through thorough research and studies, Phillips states high quality protein is best at breakfast, an intake of 1.2-1.6 g/kg/day protein is optimal, and high quality animal based protein provides the best amino acids. This article also states that athletes thrive and benefit with about twice the intake of protein RDA.
23. Volek, J. S., Forsythe, C. E., & Kraemer, W. J. (2006). Nutritional aspects of women strength athletes. British Journal of Sports Medicine, 40(9), 742–748. http://doi.org/10.1136/bjsm.2004.016709
This article illustrates how women athletes should put a higher emphasis on protein intake over carbohydrates. It is determined women athletes need a higher energy intake compared to males due to fatigue and irritation during menstruating. A recommended intake of 1.4-1.8 g/kg for athletes and although some articles state adverse effects, this study states there is no justification for limiting protein.
24. Wilson, J., & Wilson, G. J. (2006). Contemporary Issues in Protein Requirements and Consumption for Resistance Trained Athletes. Journal of the International Society of Sports Nutrition, 3(1), 7–27. http://doi.org/10.1186/1550-2783-3-1-7
This journal’s purpose is to consolidate information regarding protein intake and the needed consumption for athletes. Through comparison of multiple studies done by Tarnopolsky, Burke, and Vukovich, the author came to the conclusion timing, pattern, and quality of protein intake all has some affect on athletes. Though know specific amount of protein per day was stated to be optimal, the author states Dangin found an increase in synthesis when 23-33 g of protein were consumed. It is found that alternating normal meals with fast digesting sources and supplementing with essential amino acids may enhance protein synthesis and overall performance.