Spend enough time in the average weight room and you might walk away thinking that running is the root of all exercise evil: It does a lousy job at burning fat. It's less exciting than C-SPAN and, haven't you heard, it messes up your knees. But if you've been avoiding the treadmill based on the word of the guy who seems to live under the squat rack, you might want a second opinion.
Running is far from immune to scrutiny, as this very site has proven multiple times over, but the negative long-term impact it has on the joints is often wildly overstated, if not flat-out wrong. As Janet Hamilton, an exercise physiologist and run coach with Running Strong in Atlanta puts it, "Joints are meant to move. And running is arguably one of the most natural movements you can do as a human.” Hamilton points to research that consistently shows running—and running a lot—actually improves knee health.
She's not wrong: In one study of nearly 100,000 runners and walkers, researchers found that frequent running did not increase the risk of osteoarthritis—the most common form of arthritis, linked to wear and tear of protective cartilage and connective tissue—even among seasoned marathoners. In fact, researchers found that osteoarthritis was half as common in runners as it was in walkers. Of course, there's a good chance that the running group was self-selecting—that people who didn't experience knee pain in the first place were the ones who stuck with running. But it still says something that after a seven-year followup among people who had no osteoarthritis to begin with, it was walkers who developed knee problems in greater numbers.
X-ray evidence suggests that osteoarthritis is actually more common in soccer players and weightlifters than it is in long-distance runners, says Leigh-Ann Plack, a physical therapist and advanced clinician with the Hospital for Special Surgery in New York City, and author of a review on running and osteoarthritis.
Hamilton thinks the lower risk of osteoarthritis could be due to the fact that running stimulates the production and circulation of synovial fluid, a type of lubricant that nourishes the joints, as well as the fact that runners—at least, more serious ones—tend to maintain better strength and mobility in their muscles. When researchers at Brigham Young University stuck runners with needles to extract and study their synovial fluid, they found that 30 minutes of running decreased the fluid’s levels of inflammatory proteins linked with poor cartilage turnover. (It's worth noting that the study was small, and the researchers were unable to get enough synovial fluid from about half of the subjects.)
So if running is so great for your knees, then why do so many people complain of knee clicks, or a condition literally known as runner's knee? Partly because the vast majority of people who run have a combination of muscle imbalances and less-than-stellar form, says James Gladstone, an orthopedic knee surgeon and sports medicine specialist at Mount Sinai Hospital in New York City. “The best thing you can do for your knees as a runner," he says, "is make sure to have proper mechanics and proper muscle balance."
Running can also backfire in people with pre-existing osteoarthritis or knee damage, since it can stress the knee with up to eight times the force of walking, according to one review. In healthy subjects, this can be a good thing—stress causes microscopic damage to the cartilage, and as you recover, the tissue grows back stronger (it's like building muscle in that way). However, that stress can be too much for already-osteoarthritic knees to handle, Gladstone says.
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Even if you're not prone to injury, following these guidelines will help you stay that way the next time you step on a treadmill:
How To Prevent Injury From Running
Strength coaches like to say, “Running doesn’t make you strong. But you need to be strong to run.” This Insta-worthy expression has some truth to it, largely because running is a repetitive exercise that involves a select group of lower-body muscles, a limited range of motion, and only hits one plane of movement, Plack says.
For example, running does little to train the hip abductors, the muscles on the outside of the hip that help you move from side to side, Hamilton says. As a result, many runners have underdeveloped abductors. Research shows that weak abductors can lead to IT Band syndrome—a persistent ache on the outside of the knee that just won’t quit. “Begin running only after you have built a foundation of strength—muscle and tissue strength, not just aerobic strength—to support it,” Hamilton says. Once you start running, perform some form of multi-planar (forward-and-backward, side-to-side, and rotational) strength training at least a couple of times per week.
Deal With Underlying Issues.
If you have issues with your skeletal alignment, such as flat feet, high arches, knock knees, bowed legs, or leg-length discrepancies, get some help from a trained professional, Hamilton says. The same goes if you’ve had knee aches, plantar fasciitis, or any other exercise or running problems in the past. A physical therapist or kinesiologist can help get to the bottom of any issues and address their underlying causes, which will help prevent any issues—knee or otherwise—from cropping up mid-run, she says.
Hire a Coach
Running is a natural movement, but most people don't do it correctly. For example, excessive stride length is a common form misstep that can put excessive stress on the knees, Plack says. So if you want to run faster, you shouldn’t try to take bigger strides. Schedule an appointment with a physical therapist, kinesiologist, exercise physiologist, or certified run coach to evaluate and shore up your running form. Some knee-protecting strategies may be as simple as shortening your stride or as involved as identifying and strengthening muscle imbalances, she says.
Take It Slow
Make the transition to running gradually and build your endurance slowly over time, Hamilton says. “Aerobic conditioning responds relatively quickly, but it may take longer than that for your muscles, tendons and ligaments to adapt to the training load.”
As a general rule, experts recommend not increasing your total training load (distance + speed + duration + frequency) any more than 10 percent per week. Hamilton notes that some runners may need to stay closer to five percent. Some might be best off increasing only every other week. “It’s also good to avoid applying too many versions of ‘more’ in any given workout,” she says. “In other words, do hills or a longer workout rather than hills and a longer workout.”
Schedule Recovery Time
“Overload plus recovery equals adaptation and improvement. Overload without recovery equals injury,” Hamilton says. The exact amount of recovery you need depends on multiple factors including your fitness, how hard you’re pushing yourself, your current running and strength training routine, and your overall physical and mental stress levels, she says. High-tech strategies such as heart rate variability can help you determine when your body needs light exercise or no exercise at all. But “listening to your body” will also get the job done.
Find the Right Shoe
Much like rotating the tires on your car, mixing up the running shoes you use throughout the week can lower your risk of injury, according to research from the Sports Medicine Research Laboratory in Luxembourg. Researchers believe cycling through shoes mixes up the stress placed on your joints and tissues, which prevents overuse injuries and strengthens a wider range of muscles. Hamilton recommends buying your shoes from a running specialty store that has software designed to record and analyze how various shoes affect your running form and pattern.
Don't Train Through Pain
“If something hurts, step back and investigate the situation and address the underlying cause of the symptom—not just the symptom itself,” Hamilton says. Generally, any pain that is sharp or strikes the joints is reason to cut your workout short. Sometimes the cause is obvious: Maybe you tripped over a crack in the sidewalk or got cocky and pushed your workout too hard too fast. If it isn’t, or if the pain isn’t completely gone in a couple of days, seek professional help, she says. Again, a physical therapist with a specialty in running will be your best bet for identifying the problem and solution.
K. Aleisha Fetters is a certified strength and conditioning specialist and fitness writer based in Chicago.
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