Athletic Performance

Key Points

• Background: Many recent case studies have highlighted the success of prominent vegan endurance athletes such as ultra-runners and Ironman athletes.¹
  • Creatine levels are important in strength and power training² and it is typically higher in an omnivore diet.
  • Animal protein contains branched-chain amino acids which are needed in more concentrated amounts for muscle protein synthesis than what can be provided by plant protein sources.³
    
    
• Some studies have assessed the vegan or vegetarian diet’s impact on performance outcomes indirectly by measuring maximal oxygen uptake, strength, blood acid-base status, and acute muscle protein synthesis. Other studies have measured performance outcomes by measuring time to exhaustion when cycling or blood levels of glucose and lactic acid.
  
  
• In a systematic review done by Craddock et al., only eight studies directly examined the impact of a vegetarian diet on performance.⁴ Three of these studies focused on strength training and power, four assessed both anaerobic and aerobic performance, and one examined the impact of endurance exercise on immune markers.
  
  
• In one cross-sectional study, VO2 max was measured indirectly by a stress test, and a Wingate anaerobic test provided measurements of total power.⁵ The study found that neither aerobic nor anaerobic capacity significantly differed between vegetarians and omnivores.
  
  
• One study compared strength gains following a 12-week resistance training program between participants following a vegetarian (LOV) diet or omnivore diet.³ The study found that there were no significant differences between groups for strength on any test, except for knee extensions, which the LOV group had greater increases in strength. However, the prior physical fitness status of the participants was not considered which could impact outcomes.
  
  
• One cross-sectional study compared VO2 max, peak torque using an isokinetic dynamometer for knee extensions and flexions, and body composition between 27 vegetarian and 43 omnivore male and female endurance athletes.⁶ Participants maintained a 7-day food diary. Results showed that total protein intake was lower in the LOV group, but each group was consuming adequate protein for their body weight and for endurance athletes (1.2 – 1.5 g/kg). When doing leg extensions and flexions, peak torque did not differ significantly by diet group. VO2max did not differ significantly for males, but female vegetarian athletes had higher VO2max values compared to female omnivore athletes.
  
  
• Another study comparing the performance of vegetarians and omnivores based on their creatine levels found there were no significant differences in total work output between vegetarians and omnivores despite the lower total creatine levels in the vegetarian group.²

Conclusion

Based on the available research on the impact of plant-based diets on exercise performance, endurance and power does not appear to differ between vegetarians and omnivores.

 References

1. Leischik R., Spelsberg N. Vegan triple-ironman (raw vegetables/fruits) Case Rep. Cardiol. 2014;2014 doi: 10.1155/2014/317246.
   
   
2. Burke D.G., Chilibeck P.D., Parise G., Candow D.G., Mahoney D., Tarnopolsky M. Effect of creatine and weight training on muscle creatine and performance in vegetarians. Med. Sci. Sports Exerc. 2003;35:1946–1955. doi: 10.1249/01.MSS.0000093614.17517.79.
   
   
3. van Vliet S., Burd N.A., van Loon L.J. The skeletal muscle anabolic response to plant-versus animal-based protein consumption. J. Nutr. 2015;145:1981–1991. doi: 10.3945/jn.114.204305.
   
   
4. Craddock J.C., Probst Y.C., Peoples G.E. Vegetarian and omnivorous nutrition—Comparing physical performance. Int. J. Sport Nutr. Exerc. Metab. 2016;26:212–220. doi: 10.1123/ijsnem.2015-0231.
   
   
5. Hanne N., Dlin R., Nrotstein A. Physical fitness, anthropometric and metabolic parameters in vegetarian athletes. J. Sports Med. Phys. Fit. 1986;26:180–185.
   
   
6. Lynch H.M., Wharton C.M., Johnston C.S. Cardiorespiratory fitness and peak torque differences between vegetarian and omnivore endurance athletes: A cross-sectional study. Nutrients. 2016;8:726. doi: 10.3390/nu8110726.

Key Points

• Objective: The purpose is to 1) summarize the evidence on the relationship between vegetarian/vegan diets and strength and endurance-related exercise performance, and 2) discuss the impact of vegetarian/vegan diets on systemic and molecular muscle adaptations through training.
  
  
• Methods: This review includes research from 1999 to 2021 related to exercise and vegan/vegetarian diets. 14 articles were identified and met the inclusion criteria of this review.
  
  
• Results—Nutrient intake: 
  • Vegan diets are usually higher in carbohydrates and fiber, but lower in fat compared to omnivorous and vegetarian diets ¹.
  • Vegans consume significantly fewer saturated fatty acids and unsaturated DHA compared to
    omnivores.¹
  • Protein intake of vegans is slightly lower compared to omnivores but similar to lacto-ovo vegetarians. Omnivores tend to consume the highest amount of dietary protein.
    
    
• Results—Performance:
  • VO2max is used to measure endurance. It is influenced by cardiac output and hemoglobin concentration of blood.^2,3 A vegan diet may positively affect cardiac output by creating a lower relative (heart) wall thickness in relation to the chamber dimension 11 and improving left ventricular systolic and diastolic function4, which are positively affected by the antioxidant properties of vegan and vegetarian diets.^5-8 The improved diastolic function in vegans can be
    attributed in part to the lower intake of saturated fatty acids.⁹
  • Omnivores, vegetarians and vegans, tend to consume the same amount of iron, but the bioavailability of animal-derived heme-iron (15–35% absorption) compared to plant-derived non-heme-iron (2–20% absorption) may affect hemoglobin concentrations.¹⁰ Inadequate intake of iron can result in less hemoglobin synthesis which can negatively affect VO2max.¹¹
  • When exercise reaches an intensity of more than 60% of the VO2max, carbohydrates are used for energy.^12,13 Lower-intensity exercises such as endurance exercises utilize fat oxidation more than carbohydrates.¹⁴ Vegans and vegetarians tend to consume more carbohydrates than omnivores which could be an advantage in endurance performance.
  • Plant-based proteins tend to contain fewer amounts of essential amino acids, especially leucine.¹⁵ Muscle protein synthesis responses after ingestion of animal-derived proteins is higher compared to the ingestion of an equivalent amount of plant-based protein.¹⁶
  • Eight studies (three cross-sectional, five experimental) examined the influence of a vegetarian or vegan diet on strength performance.^17-22 The findings of these studies lead to the conclusion that a vegetarian and vegan diet can be sufficient for strength improvement, but meatcontaining diets provide an increase in skeletal muscle mass more quickly than a vegan or vegetarian diet.
    
    
• Results—The Microbiome:
  • Research shows that microbiota can be modulated by exercise training ^23,24 and diet.^25,26 Exercise affects the epithelial cells’ integrity and thus intestinal epithelium permeability.²⁷ High-volume endurance training increases epithelium permeability, promoting the passing of bacterial toxins and pathogens into the bloodstream.²⁸
  • Changes in the gut microbiome through diet occur after 24 hours and will reverse to baseline 48 hours after discontinuation.²⁹ Modulation of the immune response, oxidative stress, metabolic processes, and nutrient bioavailability all are ways in which the microbiota affects training and adaptation.²⁸
  • A high-fiber diet has a positive effect on gut microbiome composition suggesting that a diet high in fiber is favorable for positive adaptation to endurance exercise.
  • Excessive intake of protein affects the gut microbiome negatively by lowering the intestinal pH, favoring the proliferation of pathogenic bacteria. High-fat diets also reduce the favorable diversity of bacterial strains of the gut microbiome. Vitamin D contributes to intestinal homeostasis since it can influence bacterial colonization and has anti-inflammatory properties. As vegans’, vegetarians’, and omnivorous’ intake differ in these nutrients, dietary regimens might have an impact on gut microbiome health.^{26, 29}

Conclusion

Different macro- and micronutrient intake between plant-based diets may affect cardiac output, oxygen-carrying capacity, mitochondrial function, the microbiome, and substrate availability. Due to less fat intake and higher fiber intake, the vegetarian and vegan diet may positively influence the microbiome which in turn may enhance endurance exercise and immune function. Muscle mass and strength performance depend on a positive muscle protein balance over time. This can be achieved by adequate protein and essential amino acid intake from plant sources, in combination with resistance exercise.

 References

1. Rizzo, N.S.; Jaceldo-Siegl, K.; Sabate, J.; Fraser, G.E. Nutrient Profiles of Vegetarian and Nonvegetarian Dietary Patterns. J. Acad. Nutr. Diet 2013, 113, 1610–1619.
   
   
2. Pawlak, R.; Berger, J.; Hines, I. Iron Status of Vegetarian Adults: A Review of Literature. Am. J. Lifestyle Med. 2018, 12, 486–498
   
   
3. Król, W.; Price, S.; Śliż, D.; Parol, D.; Konopka, M.; Mamcarz, A.; Wełnicki, M.; Braksator, W. A Vegan Athlete’s Heart—Is It Different? Morphology and Function in Echocardiography. Diagnostics 2020, 10, 477.
   
   
4. Król, W.; Price, S.; Śliż, D.; Parol, D.; Konopka, M.; Mamcarz, A.; Wełnicki, M.; Braksator, W. A Vegan Athlete’s Heart—Is It Different? Morphology and Function in Echocardiography. Diagnostics 2020, 10, 477.
   
   
5. Tuso, P. A Plant-Based Diet, Atherogenesis, and Coronary Artery Disease Prevention. Perm. J. 2015, 19, 62–67.
   
   
6. Barnard, N.D.; Goldman, D.M.; Loomis, J.F.; Kahleova, H.; Levin, S.M.; Neabore, S.; Batts, T.C. Plant-Based Diets for Cardiovascular Safety and Performance in Endurance Sports. Nutrients 2019, 11, 130.
   
   
7. Fisher, N.D.; Hurwitz, S.; Hollenberg, N.K. Habitual flavonoid intake and endothelial function in healthy humans. J. Am. Coll. Nutr. 2012, 31, 275–279.
   
   
8. Monsen, E.R. Iron nutrition and absorption: Dietary factors which impact iron bioavailability. J. Am. Diet. Assoc. 1988, 88, 786–790.
   
   
9. Dini, F.L.; Galeotti, G.G.; Terlizzese, G.; Fabiani, I.; Pugliese, N.R.; Rovai, I. Left Ventricular Mass and Thickness. Hear. Fail. Clin. 2019, 15, 159–166
   
   
10. Hawley, J.A.; Leckey, J.J. Carbohydrate Dependence During Prolonged, Intense Endurance Exercise. Sports Med. 2015, 45, 5–12.
    
    
11. Dini, F.L.; Galeotti, G.G.; Terlizzese, G.; Fabiani, I.; Pugliese, N.R.; Rovai, I. Left Ventricular Mass and Thickness. Hear. Fail. Clin. 2019, 15, 159–166
    
    
12. Vitale, K.; Getzin, A. Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations. Nutrients 2019, 11, 1289.
    
    
13. Van Loon, L.J.C.; Greenhaff, P.; Constantin-Teodosiu, D.; Saris, W.H.M.; Wagenmakers, A. The effects of increasing exercise intensity on muscle fuel utilisation in humans. J. Physiol. 2001, 536, 295–304.
    
    
14. Król, W.; Price, S.; Śliż, D.; Parol, D.; Konopka, M.; Mamcarz, A.; Wełnicki, M.; Braksator, W. A Vegan Athlete’s Heart—Is It Different? Morphology and Function in Echocardiography. Diagnostics 2020, 10, 477.
    
    
15. Lynch, H.M.; Wharton, C.M.; Johnston, C.S. Cardiorespiratory Fitness and Peak Torque Differences between Vegetarian and Omnivore Endurance Athletes: A Cross-Sectional Study. Nutrients 2016, 8, 726.
    
    
16. Boutros, G.H.; Landry-Duval, M.-A.; Garzon, M.; Karelis, A.D. Is a vegan diet detrimental to endurance and muscle strength? Eur. J. Clin. Nutr. 2020, 74, 1550–1555
    
    
17. Page, J.; Erskine, R.M.; Hopkins, N.D. Skeletal muscle properties and vascular function do not differ between healthy, young vegan and omnivorous men. Eur. J. Sport Sci. 2021, 1–10
    
    
18. Hietavala, E.-M.; Puurtinen, R.; Kainulainen, H.; Mero, A.A. Low-protein vegetarian diet does not have a short-term effect on blood acid–base status but raises oxygen consumption during submaximal cycling. J. Int. Soc. Sports Nutr. 2012, 9, 50
    
    
19. Hevia-Larraín, V.; Gualano, B.; Longobardi, I.; Gil, S.; Fernandes, A.L.; Costa, L.A.R.; Pereira, R.M.R.; Artioli, G.G.; Phillips, S.M.; Roschel, H. High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores. Sports Med. 2021, 51, 1317–1330.
    
    
20. Haub, M.D.; Wells, A.M.; Campbell, W.W. Beef and soy-based food supplements differentially affect serum lipoprotein-lipid profiles because of changes in carbohydrate intake and novel nutrient intake ratios in older men who resistive-train. Metabolism 2005, 54, 769–774.
    
    
21. Haub, M.D.; Wells, A.M.; Tarnopolsky, M.A.; Campbell, W.W. Effect of protein source on resistive-training-induced changes in body composition and muscle size in older men. Am. J. Clin. Nutr. 2002, 76, 511–517.
    
    
22. Campbell, W.W.; Barton, M.L.; Cyr-Campbell, D.; Davey, S.L.; Beard, J.L.; Parise, G.; Evans, W.J. Effects of an omnivorous diet compared with a lactoovovegetarian diet on resistance-training-induced changes in body composition and skeletal muscle in older men. Am. J. Clin. Nutr. 1999, 70, 1032–1039.
    
    
23. van Vliet, S.; Burd, N.A.; van Loon, L.J. The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption. J. Nutr. 2015, 145, 1981–1991.
    
    
24. Simons, S.M.; Kennedy, R.G. Gastrointestinal Problems in Runners. Curr. Sports Med. Rep. 2004, 3, 112–116. 
    
    
25. Hevia-Larraín, V.; Gualano, B.; Longobardi, I.; Gil, S.; Fernandes, A.L.; Costa, L.A.R.; Pereira, R.M.R.; Artioli, G.G.; Phillips, S.M.; Roschel, H. High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between
    
    
26. Singh, R.K.; Chang, H.-W.; Yan, D.; Lee, K.M.; Ucmak, D.; Wong, K.; Abrouk, M.; Farahnik, B.; Nakamura, M.; Zhu, T.H.; et al. Influence of diet on the gut microbiome and implications for human health. J. Transl. Med. 2017, 15, 1–17.
    
    
27. Przewłócka, K.; Folwarski, M.; Kaźmierczak-Siedlecka, K.; Skonieczna-Żydecka, K.; Kaczor, J. Gut-Muscle AxisExists and May Affect Skeletal Muscle Adaptation to Training. Nutrients 2020, 12, 1451.
    
    
28. Simons, S.M.; Kennedy, R.G. Gastrointestinal Problems in Runners. Curr. Sports Med. Rep. 2004, 3, 112–116.
    
    
29. David, L.A.; Maurice, C.F.; Carmody, R.N.; Gootenberg, D.; Button, J.E.; Wolfe, B.E.; Ling, A.V.; Devlin, A.S.; Varma, Y.; Fischbach, M.; et al. Diet rapidly and reproducibly alters the human gut microbiome. Nature 2014, 505, 559–563.

Key Points

• Objective: Evaluate the effects of a plant-based diet on both aerobic and strength/power performance.
  
  
• Methods: This study is a meta-analysis and systematic review of electronic databases. Studies were included that investigated plant-based diets, had a physical performance protocol, and evaluated omnivorous diets as a control group. Based on inclusion criteria, four studies evaluated the effects of a plant-based diet on aerobic performance, and six studies evaluated the effects of a plant-based diet on strength/power in humans. The meta-analysis included a total of ten studies (36 trials and 293 subjects).
  
  
• Results: Vegan and vegetarian diets can be nutritionally adequate, but some adverse effects have been shown such as anemia, low vitamin B12, and decreased muscle creatinine.^1,2 Each of these components, individually or combined, could jeopardize athletic ability.³ Results showed that plant-based diets had a moderate effect on aerobic performance (effect size [ES]: 0·55; 95% CI 0·29, 0·81) and no effect on strength/power performance (ES: –0·30; 95 % CI −0·67, 0·07). Pooling the data showed no change in athletic performance (ES: 0.01; 95%CI: -0.21, 0.22). A plant-based diet had a small negative effect on BMI (–0·27; 95 % CI −0·40, –0·15). Additionally, data showed that individuals who consume a plant-based diet have lower BMI, which is linked to better health and body composition which may impact overall athletic performance.⁴
  
  
• Limitations: People who follow a plant-based diet are typically health-conscious and practice healthy lifestyle behaviors such as exercising, abstaining from smoking, limiting alcohol, and prioritizing sleep. These all have positive effects on performance.⁵ Therefore, it is difficult to disentangle the synergistic effects of health-related behaviors besides diet on athletic
  performance.

Conclusion

Results of this systematic review and meta-analysis showed only a moderate effect of plant-based diets on aerobic exercise performance and no effect on strength/power compared to individuals consuming omnivorous diets. While there may be weight-related and environmental advantages to following a plant-based diet, findings suggest that plant-based athletes can obtain similar athletic performance standards as omnivores with a balanced diet and proper training.

 References

1. Haddad EH, Berk LS, Kettering JD, et al. (1999) Dietary intake and biochemical, hematologic, and immune status of vegans compared with nonvegetarians. Am J Clin Nutr 70, 586S–593S.
   
   
2. Rogerson D (2017) Vegan diets: practical advice for athletes and exercisers. J Int Soc Sports Nutr 14, 36.
   
   
3. Dinu M, Abbate R, Gensini GF, et al. (2017) Vegetarian, vegan diets and multiple health outcomes: a systematic review with meta-analysis of observational studies. Crit Rev Food Sci Nutr 22, 3640–3649.
   
   
4. Aragon AA, Schoenfeld BJ, Wildman R, et al. (2017) International society of sports nutrition position stand: diets and body composition. J Int Soc Sports Nutr 14, 16.
   
   
5. Deriemaeker P, Alewaeters K, Hebbelinck M, et al. (2010) Nutritional status of Flemish vegetarians compared with non-vegetarians: a matched samples study. Nutrients 2, 770–780.

Future Directions

Based on the findings from this topical review, researchers may consider the following suggestions for future research.

Vegan Diets: More studies are needed investigating the effects of a vegan diet on athletic performance.

Professional Athletes: Much research has been conducted in recreational athletes. Future studies should investigate differences and main effects of plant-based diets on athletic performance in professional/elite athletes.

Endurance Exercise Capacity: Future research should investigate the effects of various plant-based diets on endurance in varying levels of athletic performance.

Long-Term Adherence: Studies lasting >6 months should be conducted to investigate the effects of long-term adherence on athletic performance.

Diverse Populations: Future studies should investigate the effects of plant-based nutrition and athletic performance across racial, ethnic, age, and gender groups including differences between recreational and professional athletes.