Running is among the most common forms of exercise-- and many people either love it or hate it. But to a small percentage of the human population, running isn't just a leisurely jog. It's about going the distance— literally (ultra-marathon, anybody?). And while it's clear running in general has many health benefits, is pushing the body so far more detrimental than beneficial to our muscles and joints?
It’s in Our Genes, Baby – The Need-to-Know
Most other mammals easily outrun humans over short distances because they’re able to utilize all four limbs when galloping. But over long distances, most quadrupeds tend to overheat because of their excess hair and lack of sweat glands The Evolution of Marathon Running. Lieberman, DE., Bramble, DM. Department of Anthropology and Organismic, Harvard University, Cambridge, Massachusetts 02138. Sports Medicine, 2007; 37 (4-5): 288-290.. Humans, on the other-hand, who (usually) have less hair and more sweat glands, can typically keep their cool better over long distances.
This was all pretty useful back when humans hunted animals for miles at a time, forcing their game to tire out The Evolution of Marathon Running. Lieberman, DE., Bramble, DM. Department of Anthropology and Organismic, Harvard University, Cambridge, Massachusetts 02138. Sports Medicine, 2007; 37 (4-5): 288-290.. But despite its evolutionary advantage, running miles and miles on end can indeed pose serious risk to the body’s musculoskeletal system. Osteoarthritis, marked by the wearing down of cartilage, is one major concern in distance runners because of extended trauma and possible overuse of joints in the lower extremities Does Long Distance Running Cause Osteoarthritis. Cymet,TC., Sinkov, V. Johns Hopkins School of Medicine, Owings Mills, MD 21117-4713, USA. The Journal of The American Osteopathic Association, 2006; 106:342–345.. This can result in joints lacking their natural lubrication and the bone-on-bone friction is as painful to endure as it is to imagine. Ouch.
Making It Safe to Go Long – Your Action Plan
Because joints naturally and gradually lose cartilage over time, almost everyone experiences some symptoms of osteoarthritis as they age. But repetitive, high impact activity like distance running can cause symptoms decades before they might otherwise appear.
One key to minimizing injury from distance running is to avoid dramatic increases in mileage or intensity. Excess wear and tear can most easily result when runners push themselves too hard too quickly, undermining the body’s ability to adapt to increased stress on joints Evidence-Based Treatment of Hip and Pelvic Injuries in Runners. Geraci, MC., Brown, W. Physical Medicine and Rehabilitation Clinics of North America, 2005 Aug;16(3):711-47.. A good standard for increasing mileage is the so-called "10-percent rule," which states there should be no more than a 10 percent distance increase from week to week. Another way to add a layer of protection against potential injury is to use resistance training to strengthen the muscles that stabilize the tendons and joints.
There are other potential dangers to keep aware of as well. Obviously, dehydration can be a serious problem-- but surprisingly so is over-hydration, which may dilute the body's salt level too much in a dangerous condition called hyponatremia Hyponatremia among runners in the Boston Marathon. Almond, CS., Shin, AY., Fortescue, EB., et al. The New England Journal of Medicine, 2005 Apr 14;352(15):1550-6.. In the 2002 Boston Marathon, 1 out of 8 runners were found to have a serious fluid and salt imbalance due to drinking too much water/sports drinks.
Finally, awareness of personal quirks and tendencies goes a long way in preventing distance-related injury. While some distance junkies have found success with barefoot running or in minimalist shoes, others need to take measures above and beyond the norm to ensure joint safety. Flat-footed runners are especially prone to repetitive stress injury and often need to take special precautions (like wearing custom insoles) to prevent injuries like shin splints, back pain, and, of course, our frenemy here, osteoarthritis.
Distance running can be a simple and effective— and, some would say, even addictive— way to stay in shape, build endurance, and burn calories. But, as with most forms of exercise, it’s not without its risks, especially in regard to repetitive stress injuries. Start off slow, build up gradually, and consult with a podiatrist (also known as your friendly neighborhood foot doctor) if any questions or pains arise. As our prehistoric ancestors would say, happy hunting (but, as always, in moderation)!
The Expert's Take
"Running is a great fitness test, however the majority of those who chose long distance running as exercise are rarely prepared to run. Should we run to get fit or get fit to run? If you talk to any track coach, he will tell you running mechanics are not only important in improving performance, but also in preventing injury.
For example, a lack of dorsiflexion can be responsible for plantar fasciitis. While running may be one of the best fitness tests, I believe there are several weaknesses runners typically have and there are some corrective exercises they can do to prevent injury.
The glutes are both hip extensors and rotators that are a very common undeveloped muscle in long distance runners. Glutes are typically only used during intense movements like sprinting, walking up stairs, and lifting heavy objects. Several exercises such as squats, lunges, and glute bridges can be performed prior to running to ensure a more power stride and even prevent injury. While you can add resistance to any of these exercises, it is best to first master them with just your own body weight.
Besides knee pain, the second biggest injury I see in long distance runners is plantar fasciitis. During warm ups runners should emphasize toe up in order to activate anterior tibialis and prevent injury."
Updated October 2011