Endurance

Plant-based diets give endurance athletes an edge

By WhyStopHarmingAnimals.com

People who eat plants have at least as much endurance as people who eat meat[2][3][4][5], and the best pooled evidence says they have more[1]. A 2024 meta-analysis found a moderate aerobic advantage on plant-based diets with no cost to strength[1]. Studies of recreational runners find vegan race times no slower[3]. One of the earliest recorded comparisons, run at Yale in 1907, was a rout[8].

The meta-analysis

Damasceno and colleagues pooled trial data in the British Journal of Nutrition in 2024[1]. Plant-based diets had a moderate positive effect on aerobic performance, with an effect size of 0.55 (95% CI 0.29–0.81)[1], and no effect on strength or power in either direction[1]. An athlete who switches to plants has no reason to expect to lose strength and some reason to expect better aerobic capacity[1].

Individual studies fit that result. Boutros and colleagues (European Journal of Clinical Nutrition, 2020) compared 56 healthy, young, lean women, 28 vegan and 28 omnivore, who trained the same amount each week[2]. The vegans had higher estimated VO2 max, and muscle strength did not differ[2]. The study was observational, so it can’t separate the diet from anything else the vegan women did differently, but it gives no sign that their food held them back[2].

Race times

The NURMI study (Wirnitzer and colleagues, Nutrients, 2023) looked at recreational distance runners[3]. After accounting for differences in training, best half-marathon and marathon times did not differ significantly between omnivores, vegetarians and vegans[3]. Nebl and colleagues (Journal of the International Society of Sports Nutrition, 2019) tested ambitious recreational runners and found no significant difference in exercise capacity across vegan, lacto-ovo-vegetarian and omnivorous diets, and concluded that a vegan diet can be a suitable alternative[4].

Stanford’s SWAP-MEAT Athlete study (Roberts and colleagues, Nutrition Journal, 2022) rotated recreational athletes through three diets: whole-food plant-based, one built on plant-based meat alternatives, and an animal-based diet[5]. Performance held on both plant diets[5]. Each phase lasted four weeks, which is short[5].

Matching omnivores is already enough to dispose of the claim that you need meat to go the distance[4]. The meta-analysis suggests plants add something on top[1].

Why plants may help

Barnard and colleagues reviewed plant-based diets for endurance sports in Nutrients in 2019[6]. Plant-based patterns improve blood lipids and blood flow, and their carbohydrate refills the glycogen that fuels long efforts[6]. In the research they reviewed, a vegetarian pattern that was mostly vegan reduced visceral fat and raised VO2 max even without weight loss[6]. In a marathon the heart is often what limits a runner, and plant diets tend to treat the heart well. For people who run far, recovery and cardiovascular safety matter too[6].

Pohl and colleagues (Nutrients, 2021) reached a similar view: the macronutrient mix of vegan and vegetarian diets, with plenty of carbohydrate and antioxidants and benefits for the lining of blood vessels, has potentially advantageous properties for endurance[7], and research has not shown a consistent penalty[7]. Craddock’s 2016 review of older trials had found vegetarian diets neither helped nor hindered performance[7]. The newer meta-analysis is the one that found an advantage[1][7].

Yale, 1907

Irving Fisher tested about 49 men: Yale athletes who ate meat, athletes who avoided flesh, and sedentary vegetarians from Battle Creek who were physicians and nurses[8]. He published the results in the Yale Medical Journal in March 1907[8].

In a test of how long each man could hold his arms out, the meat-eaters averaged about 10 minutes and the flesh-abstainers lasted about five times as long[8]. Only two of fifteen flesh-eaters held out past 15 minutes, against twenty-two of thirty-two abstainers. None of the meat-eaters reached half an hour. Fifteen of the abstainers did: nine went past an hour, four past two hours, and one past three hours, at 200 minutes. The best of the meat-eaters, a football guard, quit at 22 minutes.

On deep knee-bends the meat-eating athletes averaged about 383 and the plant-eating athletes about 927[8]. The sedentary vegetarians, people who spent most of the day sitting, averaged about 535 and still beat the Yale athletes who ate meat[8]. A nurse who had never eaten meat in her life reached 2,400.

Fisher was not a vegetarian[8], and he wrote that the result came “much to my surprise[8].” He concluded that the flesh-eating athletes were “very far inferior in endurance to the abstainers, even the sedentary group.” On March 22, 1907, The New York Times reported that Yale’s flesh-eating athletes had been beaten in severe endurance trials[9], under the headline “Vegetarians the Stronger[9].”

The study was small and old, and arm-holds and knee-bends are nothing like a modern VO2 lab[8]. NutritionFacts’ account of the early research also describes an 1896 Vegetarian Cycling Club and a 1904 Belgian lifting test in which the plant-eaters reportedly managed about 80% more repetitions, though the English primary source for the Belgian test is hard to locate[10]. Fisher’s numbers are the ones that survive in the archives[10], and the modern studies point the same way he did more than a century ago[1][8].