Stress Fractures and the effect of alcohol on working out
Can “platelet-rich plasma” cure my tennis elbow or Achilles tendon?
One of the minor subplots in the media frenzy that engulfed Tiger Woods in late 2009 was his connection to a Toronto sports doctor named Anthony Galea, who said he had injected Woods at least four times with “platelet-rich plasma,” or PRP, to help his recovery from knee surgery. Further investigation revealed a long list of prominent athletes from Olympic sports and almost every major professional league who had received PRP therapy during injury rehab.
For the general public, the investigation offered a rare peek into the world of cutting-edge, sometimes experimental sports medicine treatments that top athletes rely on. It also offered hope for recreational athletes sidelined by chronic tendon injuries—was it possible that a simple, non-invasive procedure might heal them? In fact, Galea reported that about 40 percent of patients seeking the treatment from his clinic were recreational rather than professional athletes. But researchers are still hotly debating whether the technique actually works, and if so, how it should be used. (Despite rumors to the contrary, PRP is not illegal; however, since the beginning of 2010, elite athletes who are subject to drug testing have had to apply for a “therapeutic use exemption” before receiving PRP therapy, and injections of PRP directly into muscle tissue are banned.)
The technique is designed to help injuries that don’t heal well on their own. For example, unlike muscles, tendons have a very poor blood supply, so minor tears and inflammation tend to heal slowly. PRP therapy involves drawing a small amount of the patient’s own blood, spinning it in a centrifuge to concentrate the most useful components (the platelets), and then re-injecting this concentrated plasma at the injury site. The platelets then release various “growth factors” that stimulate the body’s natural healing response.
The technique isn’t new—the first attempts to harness the growth factors in platelets date back at least to the early 1980s, and surgeons have also experimented with PRP to aid in bone grafts. But it’s only in the last five years or so that small pilot studies have shown the technique’s potential for tendon injuries. Initial results for Achilles tendinopathy and tennis elbow—two stubborn tendon problems that often resist non-surgical treatment—were promising, but the studies were neither randomized nor placebo-controlled.
Only now are the first proper clinical trials emerging, and the verdict remains unclear. A team of researchers in the Netherlands tested the technique on patients with chronic Achilles tendon problems, publishing the results in 2010 in the Journal of the American Medical Association. Fifty-four patients received an injection of either platelet-rich plasma or a saline placebo, then undertook a program of rehab exercises. After 24 weeks, the two groups were indistinguishable, dealing a blow to hopes that PRP would prove to be a “magic bullet.”
The next month, a different Dutch team published another clinical trial, this time with positive results. In a group of 100 patients with tennis elbow, 73 percent of those given PRP reduced their pain by at least 25 percent after a year, whereas only 49 percent of those who received a corticosteroid injection achieved similar results. Again, the study was blinded so that the patients didn’t know which procedure they were receiving.
The shots typically cost about $500 each, and a full course of treatment including imaging can exceed $2,000. With that in mind, you can balance the benefits of a promising but unproven treatment against the cost—and how long you’ve been struggling with the injury. It’s worth noting that, even in the unsuccessful trial, both the PRP and placebo groups did improve significantly during the study (by about 20 points on a 100-point pain scale). The authors note that “placebo response is amplified when a treatment is invasive and raises high expectation.” In other words, the shots could work if you believe in them.
How can I reduce my risk of stress fractures?
Evan Lysacek had one in his left foot the year before winning the 2010 Olympic gold in men’s figure skating. Tiger Woods had two in his left leg. A Globe and Mail reporter even got one from dashing between parties at the Toronto International Film Festival in high heels. Stress fractures are among the most common—and dreaded—diagnoses in athletes. Striking most often in sports that involve running and jumping, they usually signal the end of an athlete’s season, since the only treatment is rest for 8 to 10 weeks or more.
Bone is a living tissue, in a constant balance between breakdown and repair. When the damage from repeated impacts builds up more quickly than it can be repaired, microscopic cracks begin to form. Eventually, these cracks join together to form a stress fracture—a hairline crack in the bone that results from weeks or months of accumulated pounding rather than from a single traumatic blow. The single most important factor in preventing stress fractures is having strong, healthy bones. But new research suggests a couple of other factors that might reduce your risk.
The first comes from researchers at Iowa State University, who used a computer model of bone damage and repair to estimate the effects of changing your stride length. Basically, if you shorten your stride, you’ll have more foot-strikes per mile (and thus more impacts jarring your bones), but each foot-strike will be a little gentler. So which effect predominates? The researchers had 10 runners run on a treadmill with different stride lengths, measuring the relevant forces with motion-capture cameras and force plates, then plugged the data into their computer model. The conclusion: shortening your stride length by 10 percent reduces stress fracture risk by 3 to 6 percent.
Changing your running stride definitely isn’t easy. But other studies have found that one of the chief sins of inexperienced runners is overstriding: elite runners tend to take about 180 steps a minute regardless of how fast they’re running, while less experienced runners take fewer steps. So focusing on taking short, quick steps could have multiple benefits—including lowering your stress fracture risk.
The second factor comes from a study of 39 female runners, half of whom had a history of stress fractures. Researchers at the University of Minnesota took a series of measurements to determine the size, structure, and density of the subjects’ bones and muscles. Not surprisingly, the shin bones in the stress fracture group were smaller by 7 to 8 percent, and weaker by 9 to 10 percent. Interestingly, though, the bone differences were exactly in proportion to the size of the calf muscles, and there was no difference in bone mineral density.
This suggests that the women in this group who suffered from stress fractures weren’t guilty of not getting enough calcium—instead, the relative weakness of their bones was a response to the lack of muscle in their legs. And the fix is simple: strengthen your calf muscles by doing exercises like calf raises. The extra muscle should help cushion some of the impact when you run and jump and also stimulate your shin bones to get stronger. (And this doesn’t apply only to your shins: the best way to ensure the bones throughout your body are strong is to keep the surrounding muscles strong.)
Should I exercise when I’m sick?
The answer to this question seems obvious: if you’re sick, your body needs its strength to fight off the infection. But exercise is a deeply entrenched habit for many people, so when illness strikes, they want to know if they can exercise without doing themselves harm.
For any sort of serious illness, there’s no doubt that you shouldn’t exercise. The question usually arises with less serious conditions like colds, which are unpleasant but not debilitating. Although there isn’t a great deal of research on the topic, many researchers apply a rule of thumb known as the “neck check,” according to Thomas Weidner, the head of the athletic training program at Ball State University in Indiana. Patients are generally free to exercise if their symptoms are above the neck, like a runny nose, sneezing, or a scratchy throat. But symptoms below the neck like fever, aching muscles, or a chest cough are grounds for caution.
Weidner was responsible for a couple of unusual studies in the late 1990s in which volunteers were infected with rhinovirus, better known as the common cold, in one of the very few attempts to address this question in a controlled experiment. First, he infected 45 volunteers, who began to develop sore throats the next evening and proceeded to full-blown symptoms by the third day of the experiment. At the peak of their illness, he put them through a series of treadmill tests and compared the results to a group of uninfected controls. To his surprise, he found no difference between the two groups in their running performance, lung function, or any other physiological responses. In other words, having a cold doesn’t seem to make you a worse athlete.
In the second study, Weidner infected 50 volunteers and had half of them do 40 minutes of exercise at 70 percent of maximum heart rate every second day, while the other half just rested. There was no difference between the two groups in the severity and duration of the symptoms—and in fact the exercise group reported feeling slightly better than the controls. Though they’re more than a decade old, those results haven’t been contradicted by any studies since, Weidner says. (No doubt it’s challenging to assemble a group of volunteers willing to be infected with a cold!)
There’s plenty of anecdotal evidence to support Weidner’s finding that light exercise when you have a cold makes you feel better. People believe it clears the airways, or that the enhanced circulation speeds healing, or that it simply feels good. It’s well established that moderate exercise boosts immune function—and one study even found that a single 45-minute treadmill run helped mice battle a virus. So it’s not that far-fetched to believe that staying active while sick might have real physical benefits. For now, though, we’ll have to be content with Weidner’s finding—that at the very least, exercising with a cold doesn’t make your symptoms worse.
Will having a few drinks affect my workout the next day?
That depends on what you mean by “a few.”
In 2010, researchers in New Zealand published a surprising study that found significant delays in muscle recovery when the subjects drank a “moderate” amount of alcohol after a strenuous workout. The subjects did a series of leg exercises, then had 90 minutes to drink either straight orange juice or a mix of vodka and orange juice before going to bed. Over the next three days, the alcohol group didn’t report feeling any additional leg soreness compared to the OJ group—but their loss of strength in a series of tests was 1.4 to 2.8 times greater.
However, “moderate” in this case was 1 gram of ethanol per kilogram of body weight, corresponding to about 6.5 bottles of 5-percent-alcohol beer for the subjects, who had an average weight of 193 pounds (87.6 kilograms). “When you look at how much athletes are reported to drink in the scientific literature, this is actually a moderate dose,” says Matthew Barnes, a researcher at Massey University and the lead author of the study. “This is not just in New Zealand but in the majority of Westernized countries where contact team sports are played.”
Sure enough, researchers have recorded some fairly prodigious feats of drinking by athletes—Barnes points to one study of rugby players in which post-match consumption reached as high as 38 units of alcohol, or 22 bottles of beer. Since most people are dealing with smaller quantities, Barnes ran a follow-up study that cut the dose in half, to 0.5 grams of alcohol per kilogram of body weight. The results, published in the European Journal of Applied Physiology, offer good news: he found no difference at all in recovery between the alcohol and orange juice groups.
He and his colleagues are now conducting further experiments that suggest the higher dose of alcohol may affect the central nervous system rather than the muscles themselves, weakening the signals sent from the brain to the muscles. However, it’s possible that there are also changes in the muscles, or in the levels of hormones like cortisol and testosterone.
Two other key factors affect how well you recover after a workout-booze combo, Barnes says: rehydration, and refilling your carbohydrate stores. Drinks containing more than about 4 percent alcohol have a diuretic effect; drinking a standard shot of hard alcohol will make you expel four times that much urine. The solution here is simple: drink a glass of water for every alcoholic drink you have during the evening.
In order to recover properly after a workout, replenishing your energy stores during the two hours following exercise is crucial. Some animal studies have suggested that alcohol can directly hinder your ability to restore carbohydrate levels, but these results remain disputed. However, problems definitely arise if the calories you consume from alcohol displace more functional calories. A 2003 study of Australian cyclists found that simply adding alcohol to a post-workout meal didn’t change the amount of carbohydrate stored. But if the alcohol replaced some of the calories in the post-workout meal, carbohydrate stores were 50 percent lower after eight hours, and still lower 24 hours later.
Overall, these studies fit with the prevailing wisdom that one or two drinks a night won’t have any negative effects on your health and performance. Indeed, light to moderate drinkers appear to have 20 to 40 percent lower risk of heart disease, among other reported benefits. But if you’ve arranged a big night out with a group of Kiwi rugby players, you might want to schedule a fairly light workout for that day—or at least, don’t expect to set any personal bests in the days that follow.
CHEAT SHEET: INJURIES AND RECOVERY
• “RICE” (rest, ice, compression, elevation) is important immediately after soft-tissue injury, but after acute swelling has passed switch to “MICE” (mobilization, ice, compression, elevation) to avoid scar tissue build-up.
• Ice baths may help speed recovery from muscle soreness, using bouts lasting at least five minutes and temperature of 50°F (10°C).
• Heat packs can loosen tight or injured muscles, but only if they’re near the surface. Use heat before exercise to aid warm-up, not after.
• Massage doesn’t flush away lactic acid but may speed recovery from muscle soreness. Use a practitioner who specializes in sports massage.
• Anti-inflammatory drugs like aspirin and ibuprofen are not suitable for chronic, nagging injuries or to prevent pain before it happens. They carry health risks and may interfere with the effects of training. However, they’re suitable for acute injuries.
• After an extreme event like a marathon, your body will return to normal within about a week, but neuromuscular fatigue can persist for several weeks.
• “Platelet-rich plasma” is a component of your own blood, injected to speed healing of tendon injuries. Recent clinical trials suggest it’s not a “miracle cure,” but it may speed healing in some patients.
• The best way to keep your bones strong enough to avoid stress fractures is to strengthen the muscles around them. Shortening your running stride may also help.
• For “above-the-neck” symptoms like a runny nose or a sore throat, exercising with a cold appears to have no ill effects, and may even speed recovery slightly.
• Having a few drinks won’t affect your next day’s workout, but more than four or five (depending on your weight) can slow muscle recovery and displace other needed nutrients.