Exercise injuries: No rhyme nor reason
Posted on Monday, December 1, 2008
The three women are all serious athletes, and they work together at a small research and development firm in New Jersey.
One had a single serious injury when she was a teenager doing gymnastics and skiing. She has had knee surgery and is missing a piece of stabilizing cartilage in her knee. She exercises a lot, running nearly every day for 10 miles at a time and routinely wearing her shoes down to a nub. She is seldom hurt.
One recently had a hairline crack in the tibia, a serious overuse injury from running. She was training for a marathon at the time.
The third never does long-distance training. She varies her workouts to avoid overuse syndromes. And yet she has had one injury after another for the last five years.
The one with the chronic injuries is more careful and also younger than the other two.
And that leads to some of the most difficult problems in exercise science: Why do some people become injured even though they try to do everything right, while others, who flout every rule, usually avoid injury ?
And how can the injury-prone protect themselves ?
Exercise scientists say they have a few answers that can help with some common injuries. But all too often injuries remain a mystery, and people may have to figure out how much exercise is too much for them and what sort of routines tend to hurt them.
“We don’t have enough definitive evidence to say, ‘This causes an injury and even if you don’t have an injury you should change it, ’” said Stephen Messier, who directs the biomechanics lab at Wake Forest University.
Much of the research available focuses on running injuries. But the same principles apply to swimming, tennis, bicycling or basketball.
“I think that there is a general quality of ‘ heartiness,’ or ‘robustness,’ that may influence who gets hurt and who doesn’t,” said Carl Foster, director of the human performance laboratory at the University of Wisconsin at La Crosse. “I’ve never seen any systematically collected data, and I’m not even sure what one would measure, but anyone who has worked with athletes for any time at all has seen that there are just some people who are fragile and some who aren’t.”
Sometimes injuries have a simple fix — like making sure your bicycle fits properly or improving your swimming stroke. More often, they do not. And people tend to get the same injury repeatedly.
“My guess is that it is probably your weak link, perhaps due to your structural malalignment,” said Irene Davis, the research director at the Drayer Physical Therapy Institute at the University of Delaware. “You probably have an innate predisposition for that injury.”
For example, people differ in the way their tissues, bones and ligaments respond to increased training, said Dr. Gordon Matheson, an exercise physiologist and orthopedic surgeon at Stanford University and a past editor of the journal Physician & Sportsmedicine.
“You might increase your running 10 percent a week but I might be only be able to handle 8 percent a week,” Matheson said.
Then there is muscle strength and endurance, which also can vary from person to person. If your muscles tire, more stress is placed on bones and tendons, which can lead to injury.
And there is the alignment of your skeleton. You might be fine running 30 miles a week, but increasing that to 40 miles means the likelihood of an injury also goes up.
In addition, Matheson said, some people “can handle distance but not pace.” He explained: “It’s a big jump from a 9-minute mile to an 8-minute mile, and shock absorption can decrease substantially making that move.”
But Davis’ recent research has identified a few biomechanical features of people who tend to get two common injuries — runner’s knee and stress fractures of the tibia — and showed that it’s possible to change their biomechanics. The investigators, though, have not yet confirmed those findings with rigorous studies.
Davis said that runners whose knees hurt tended to drop a hip with each step while, at the same time, their knees cave inward by an excessive amount.
Using a computer monitor and cameras, she showed runners where their hips and knees were when they were running on a treadmill and where they should be. They learned to change their alignment and, according to Davis, they said their knee pain decreased.
Stress fractures of the tibia may have a very different cause, Davis said. Those who get it often have a characteristic gait, she said. The runners tend to strike the ground hard with their heel. Her solution is to train runners by having them run on treadmills that can measure the force of each step. The runners can see how hard their feet hit the treadmill. That still leaves a lot of injuries that are largely unexplained. And that means that for some people, injuries may just be a fact of life. But that does not mean they can’t have fun.
Just ask Dr. Alan Garber, a professor of medicine at Stanford who has a daunting injury history — stress fractures, torn ligaments, even a hip injury from vigorous workouts on a rowing machine. “I go into recovery mode,” he said. At each stage of his recovery, he seizes upon the things he can do. When he had a severe stress fracture, he could not kick when he tried to swim. So he swam with a pull buoy. The day he was finally able to kick was fabulous. He graduated to pool running, jumping into the deep end of a pool and moving his legs and arms as though he were running. He loved it. He could use an elliptical crosstrainer when he got a little better. Sheer joy. Ordinarily, swimming or pool running or an elliptical cross-trainer would seem like a bore. But he finds himself looking forward to those workouts. And, he said, he tells himself: “I’ve recovered before. I just have to switch to exercises that I can still do.”
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