What are the Limits of the Human Runner


In 2008, Olympic legend Usain Bolt set the current 100-meter world record and triggered a flurry of debate: Have humans reached the limits of their running potential? It seems the only way this debate will end is with the passage of time, but that doesn’t stop researchers from funding studies.

For the average Joe runner, the goal may not be to beat Usain Bolt, but it’s often to go faster and farther than ever before. A personal record is always the measure of success. But it turns out even this is under debate. Some physicians now feel when it comes to speed and distance we should aim for slow and steady. They say that’s how we win the race of life.


While Usain Bolt can reach speeds of 28 miles per hour, he’s not exactly the average human runner. Most of us will never see a rate close to, and certainly not above, 15 miles per hour. Even a fast human runner can only keep that up for a short distance. Then again, most of us aren’t training for the Olympics.

When Bolt broke the world record in 2008, some wondered if he’d ever beat his own unfathomable record. Some researchers say he, or someone of his talent and skill, could but only by a little bit.

The central question bothering researchers has to do with the amount of force our human limbs can take. For a while, researchers believed that we’d nearly maxed out, that anymore and our legs would snap.

However, newer studies suggest there’s more to it than that. The question isn’t how much force can our legs absorb, but how quickly do our muscle fibers contract to get our feet back off the ground once the force has been applied?

The full weight of the force happens in the first instant of contact, so if our muscle fibers contract quickly enough (which is possible), our foot will be off the ground in sufficient time to avoid the full impact of force. This means that the potential for speeds up to 40 miles per hour exists.

That’s much faster than Usain Bolt runs and tough to imagine. It is certainly awe-inspiring, but it turns out running that fast isn’t something to which we should aspire.

While running has long been associated with healthy, long lives, studies now show that less is more. It turns out that those who run more than 7 miles per hour more than a few times a week increase their risk for cardiovascular disease and mortality.

So don’t let Usain Bolt and his compatriots make you feel bad about yourself. While we may discover shortly a human being who can reach that incredible speed of 40 miles per hour, we probably don’t want to hurry that future into the present.



There are plenty of animals who run faster than human beings. Cheetahs, of course, leave us in the dust with speeds up to 70 miles per hour. However, when it comes to distance running, it turns out humans lead the pack.

Humans can run farther than even the most powerful animals. We shouldn’t be surprised when we consider the thousands upon thousands of people who sign up and run in marathons each year.

Dean Karnazes, perhaps the world’s most famous marathoner, once ran 350 miles in just over 80 hours straight, never stopping to eat or sleep. While others have run up to 300 miles, he holds the record for distance by a long shot.

The average human, even the most seasoned marathon runner, can’t and shouldn’t do this. Some felt that Dean Karnazes shouldn’t even do this, that it wasn’t healthy. But recently, Karnazes revealed the reason behind his unique ability to run long distances without slowing down. He has a rare genetic syndrome that prevents lactic acid from building up in his muscles. Because of this, his muscles never ache or seize, and they never signal to his body that he should stop running. Obviously, we shouldn’t take our cue from Karnazes when we consider how far humans can run.

Once again the question becomes not just can we, but should we? Most physicians agree that for a person in good health who eats a healthy diet and has the proper shoes, training for and running a marathon can be beneficial for his or her overall health.

There are certainly risks. Some doctors question if the heart muscle is indeed adapted to run marathon after marathon, which is a practice that happens among marathon enthusiasts. Cardiac events, while rare, do happen on the track or soon after. A checkup before you begin training is the best preventative measure you can take.

While death is unlikely, injury and joint deterioration are almost unavoidable. Most marathon runners are well acquainted with sprained ankles, pulled muscles and aching knees.

Studies also show that cardiac health is not improved by running long distances over and over again and can cause problems in the long-term. Moderation seems to be key.

 When it comes to the question of human limitations while running, not everyone agrees if we’ve reached the limit or not. Similarly, not everyone agrees if running super fast and super far is a good and healthy thing.

The best thing you can do is discuss your personal health and ability with your doctor. He or she can help guide you whether you’re beginning a running regime, training for a marathon or signing up for your 50th ultramarathon.

Do you think we as a human race have gone as far and as fast as we can? Do you believe we should keep pushing? If you’re a runner, how often do you get a checkup? Let us know your thoughts!

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