Running is bad for you because… what??!!!
Before I continue with my possibly rather harsh critique of this article, I want to point out that I rather like the look of crossfit, the workouts sound fun and very challenging, the camaraderie sounds great and very motivating, and it looks like a really good way to develop a high level of all-round strength and fitness. If I wasn’t broke, I’d probably join a crossfit box, at least if believing in pseudoscience isn’t a necessary thing in order to fit in… there’s enough bull floating around the internet from the less well informed among the paleo diet crowd already… now crossfit (who advocate a paleo diet) seem to be adding to that with this article intended to claim that long distance running is bad for you.
This was posted on a health and fitness forum, to warn runners about the “dangers” of running and other forms of endurance cardio exercise: http://crossfitmeanstreets.com/2010/09/08/chronic-cardio-is-forcing-your-body-to-kill-you-and-how-you-can-save-yourself/
The TL;DR (too long; didn’t read) of it is that they are claiming that endurance cardio such as marathon running is really bad for you, in fact it’s “forcing your body to kill you” (whatever that means) because when you run marathons your body thinks its being chased by a lion, which, according to the article, is the only reason why human ancestors would be running long distances. This then causes various stress hormones to be released which allegedly damage the body.
What I would like to say in response is as follows:
1. Seriously?? How fast do you think humans can run compared to lions? Do you think lions toyed with humans, walking behind them slowly, making them keep running for hours before finally putting them out of their misery and killing them? Err… no. There is indeed evidence from the fossil record of lower palaeolithic humans being eaten by big cats, there’s no doubt about that. However the chase would have lasted less than a minute, on account of how humans are slow at running and big cats are not. A palaeolithic human’s best chance of surviving an attack by a big cat would be to attempt to kill it with a spear (if it had one), or for the other humans in the group (we’re social animals) to throw rocks at it and try to chase it away before it managed to maim or kill the human it just attacked. Additionally, the stuff about stress hormones is incorrect… stress hormones are released in response to being in danger, not to running, and the issue of whether or not they cause damage within the body and in what circumstances is too big a topic for this post.
2. Homo erectus is believed to have hunted with the “persistence hunting” method. This method is still used by some modern hunter-gatherer tribes. It involves chasing the prey animal over long distances for hours until the animal dies from heat exhaustion or is too injured to keep on running. Humans are slow sprinters, and cannot catch another animal after a quick chase like a lion can, and Homo erectus didn’t have anything like the weapons technology of Homo sapiens. In this method, you chase the animal, it escapes, you track it down, chase it again, track it… chase it… track it.. chase it… track it… never letting it rest, until it dies from heat exhaustion or is so hot and exhausted you can finally get close enough to kill it.
Humans, with their lack of body hair compared to other mammals and ability to sweat over the whole body, can stay cool for longer and have the ability to endure running marathons, and to keep running for as long as it takes for the prey animal to die. The human gait is very energy efficient, for covering huge distances walking, jogging or running. Later humans may have learned how to trap and corner animals, how to use fire to drive them into traps and stone tipped spears to kill them and Homo sapiens invented long range weapons, but what did Homo erectus have? Homo erectus could run long distances in an energy efficient manner and stay cool by sweating and being less hairy. We evolved to be long distance runners. Does that mean we didn’t also evolve to be strong? Well, middle palaeolithic humans were very strong, neanderthals especially, but I’d be willing to bet you could train up a neanderthal to run marathons, and even if they didn’t use persistence hunting, they would have walked very long distances up and down hills and mountains, probably carrying heavy animals back home. So the fact we evolved as long distance runners does not mean that’s the only kind of exercise that can benefit health. But it does mean that long distance running isn’t bad for humans. In fact if you look at palaeolithic life, you’ll find that people needed high levels of both strength and endurance to survive (which is what crossfit advocate, so I’m not sure why they have to resort to ridiculous psuedoscience).
3. I’m aware of scientific data that links certain health problems to long distance running. However, many people who do a lot of endurance cardio don’t eat properly. It’s so common on health and fitness websites to find people who do 2-3 hours of low intensity cardio a day, while eating very little, either because they have eating disorders, or because they are acting on bad advice and believe that this is necessary in order to lose weight and/or stay thin. (The fact that people can do so much cardio while eating so little is, in my opinion, more proof that this is how Homo erectus hunted, because they wouldn’t survive a food shortage by spending all day sitting on their backside. They’d have to get out there and carry on hunting, until they managed to catch an animal. So we evolved to be able to carry on doing huge amounts of cardio on too few calories because this enabled our ancestors to survive food shortages (though not indefinitely, because the body can only go for so long on inadequate food before it starts breaking down, and it’s not necessarily what’s optimal for good health even in the short term.)) People who do lots of cardio on insufficient food would be more likely to suffer health problems, and this could be skewing the data for the health of runners in general, as it’s very common. However undereating would be the cause of the problems, not running, and undereating is also bad for you even if you don’t do any exercise at all. So I still don’t believe that long distance running is bad for a well-fed human.
The take-home message from this should be that if you’re going to run marathons, your body thinks you’re hunting, so it might be a good idea to eat a nice big meal including a lot of protein after you finish, that way your body thinks you’re succeeding at hunting. Or at the very least, eat a proper, balanced diet that includes a sufficient amount of carbohydrate and calories to support the high volume of long distance running being done. People who run marathons for fun do that, but people who do a lot of running to get fit or lose weight may not realise how much they need to eat and why eating properly is so important.
4. You made Homo erectus cry. He is good at running. He is!
image: my own sketch