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Recently, the remains of dozens of Roman gladiators were discovered in a mass grave. The clue to their identities were the rather distinct types of mortal injuries they found, like being speared in the head with a trident. Using just their skeletons, they were able to reconstruct the death blows, show just how buff they really were, and even try to reconstruct their “diet of barley and beans.” You can look at carbon isotopes and see what kinds of plants they ate; “nitrogen isotopes…reflect [any] intake of animal protein.” You can also look at the sulphur in their bones and the amount of strontium, leading commentators to submit that the best athletes in ancient Rome ate largely plant-based diets.

Then there were the legionnaires, the Roman army troopers, famed for their abilities, also eating a similar kind of diet, suggesting “The best fighters in the ancient world were essentially vegetarian.” So, if the so-called “perfect fighting machine[s],” the great sports heroes of the day, were eating mostly grains and beans, should that tell us anything about sports nutrition and the preferred diets of elite athletes? Well, most of the Greeks and Romans were “basically vegetarian” and centering their diets around grains, fruit, vegetables and beans, so maybe the gladiators’ diets weren’t that remarkable. Plato, for example, pushed plants, preferring plant foods for their health and efficiency.

So yes, “the Roman gladiators were known as [the] ‘barley men.'” But is that because barley gives you “strength and stamina”? Or was that just the basic food that people ate at the time, not necessarily for performance, but because it was just so cheap?

Well, if you look at “the modern Spartans,” the Tarahumara Indians, the ones that run races where they kick a ball for oh, 75 miles just for the fun of it, running all day, all night, and all day, maybe 150 miles if they’re feeling in the mood. What do you get if you win? “[A] special popularity with the [ladies] (although how much of a reward that would actually prove to be for a man who had been running for two days [straight] is questionable,” though maybe their endurance extends to other dimensions). “Probably not since the days of the ancient Spartans has a people achieved such a high state of [extreme] physical conditioning.” And what did they eat? The same kind of 75 to 80 percent starch diet based on “beans, corn, and squash.” And, they had the cholesterol levels to prove it, total cholesterol levels down at an essentially heart attack-proof 136. And it’s not some special genetics they have—you feed them enough egg yolks, and their cholesterol creeps right up.

Modern day Olympian runners eat the same stuff. What are they eating over there in Kenya? A 99 percent vegetarian diet centered mostly around various starches. But as in all these cases, is their remarkable physical prowess because of their diets, or in spite of their diets? Or have nothing to do with their diets? You don’t know…until you put it to the test.

“In spite of well-documented health benefits of [more plant-based] diets, less is known regarding the effects of these diets on athletic performance.” So, they “compared elite vegetarian and omnivore…endurance athletes for [aerobic fitness] and strength.” So, comparing oxygen utilization on the treadmill, and quad strength with leg extensions. And the vegetarians beat out their omnivore counterparts for “cardiorespiratory fitness,” but their strength didn’t differ. Suggesting, in the very least, that vegetarian diets “do not compromise athletic performance.”

But this was a cross-sectional study. Maybe the veg athletes were just fitter because they trained harder? Like in the National Runners’ Health Study looking at thousands of runners: vegetarian runners were recorded running significantly more on a weekly basis; so, maybe that explains their superior fitness. Though, maybe their superior fitness explains their greater distances.

Other cross-sectional studies have found no differences in physical fitness between vegetarian and non-vegetarian athletes, or even worse performance, as in this study of vegetarian athletes in India. Of course, there could be socioeconomic or other confounding factors. That’s why we need interventional studies to put different diets to the test and then compare physical performance, which we’ll explore next.

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