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Historical examples of successful plant-based athletes range from the gladiators in ancient Rome to the Tarahumara Indians who run 160-mile races for the fun of it: six back-to-back marathons. But, they weren’t put to the test until the last century or so, purporting to show beyond a reasonable doubt that athletes who regularly ate meat showed “very far…inferior endurance” to even sedentary vegetarians—meaning it’s not like the veg athletes just won because they were training harder or something. There are certainly advantages to plant-based eating, like more antioxidants to combat “exercise-induced oxidative stress”, and the anti-inflammatory nature of many plant foods that may “accelerate muscle repair” and strength recovery. But, do you have to eat this way for years, or decades, or your whole life to get these apparent benefits?

What if you took a couple guys in Texas, eating their regular Texan diet, put them through “a maximal exercise test,” then asked them to cut out the meat for four days, told them about the existence of bean burritos, then after four days tested again, measuring time to exhaustion, ramping up the treadmill to see how many minutes could they go without collapsing. And there was a significant difference, favoring the vegetarian diet, boosting the time to exhaustion by about 13 percent. Each of the subjects, all five, “had a higher time to exhaustion…following [the] vegetarian diet.”

But, who can tell me the fatal flaw to this study? Anyone catch it? They were all in the same sequence—meat first then veg. And any time you do a test a second time, you may do better just because you’re more familiar with it. If they then went back to eating meat, and their performance tanked during a third test, then you might be onto something, but this isn’t very convincing. And even if the effect is real, it may not be the meat reduction per se, but a function of improved glycogen stores from eating more carbs or something.

If you put athletes to a vegetarian versus omnivorous diet for a 621-mile race—you’ve heard of a 5k? This is a 1000k!—and you make sure to design the two diets so they get about the same percentage of carbs, the finishing rates…are identical, and total times within just a few hours of each other.

Same thing with sprinting: randomize people into veg or mixed diet groups, and no significant difference in sprint power between the two groups. They conclude that “acute” vegetarianism has no apparent adverse effects, but no apparent performance benefits either.

Same with strength training. Measure “maximum voluntary contraction” of both biceps and quads “before and after each dietary period,” and…no significant difference either way. Put all the studies together comparing physical performance in these kinds of randomized, controlled trials, where you have folks eat more plant-based for just a few days or weeks, and: “There appeared to be no differences at least acutely between a vegetarian-based diet and an omnivorous diet in muscular power, muscular strength,…or aerobic performance.”

Long-term, though, a plant-based diet can be conducive to both endurance performance and health. “Whereas athletes are most often concerned with performance, [more plant-based] diets also provide long-term health benefits and a reduction in the risk of chronic disease,” associated with a reduced risk of developing coronary heart disease—the number one killer of men and women—”breast cancer, colorectal cancers, prostate cancer, type 2 diabetes, insulin resistance, hypertension, cataracts, and dementia.” Doesn’t matter how shred, if you’re dead.

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