Everything You Know About Marathons Is Wrong
A researcher reported recently that he could find no relationship between dehydration and cramping.
By GINA KOLATA
Most runners have heard the marathon lore: Your time will be best if the weather on race day is about 55 degrees and overcast, or even drizzly. And avoid dehydration at all costs, because it will cause your muscles to cramp and you could collapse at the finish line.
But none of that is true, researchers said at a recent marathon medicine and science conference in Chicago.
The weather theory “needs adjusting,” said Scott J. Montain, a research physiologist at the United States Army Research Institute of Environmental Medicine in Natick, Mass.
“Most of what we know comes from the lay literature,” he said.
Thousands of runners are no doubt monitoring the weather forecast for Sunday, when the New York City Marathon makes its annual tour of the five boroughs. (As of yesterday, it looked promising, with temperatures expected to be in the upper 40’s and partially cloudy skies.) But the weather nostrums for marathoning that are cited so authoritatively in journal articles and textbooks are not always borne out in legitimate science. Montain and his colleagues set out to conduct a proper study.
They gathered data from 28 years of the New York City Marathon, 35 years of the Boston Marathon and 23 years of the marathons in Hartford, Vancouver, Duluth, Minn., and Richmond, Va. The routes for those marathons have barely changed over the years, and each had a large field — more than 10,000 runners. The investigators looked at the average times for the top three men and women, and at the times for the runners who placed 25th, 50th, 100th and 300th.
Elite runners ran fastest in the coldest conditions — 41 to 50 degrees. But the slowing effect with heat was not as great as had been previously reported. For every five-degree increase in temperature, times slowed by 0.4 percent.
Warmer weather had a greater effect on slower runners. On a 77-degree day, an elite runner would be about 5 percent slower than on a 41-degree day. But a runner who finished in three hours on a 41-degree day would be slowed by about 12 percent on a 77-degree day, finishing in 3 hours 21 minutes.
One reason, Montain said, could be that slower runners spend more time on the course, and the temperature generally rises through the day. Or it could be because slower runners tend to run with a larger pack. A tightly clustered group of runners generates heat and blocks it from dissipating.
Montain and his colleagues also looked at whether marathon times were better under sunny or overcast skies. Only 13 percent of records were set on cool and cloudy days.
“It is more likely that a record will be set when it is sunny or when there are scattered clouds,” Montain said. He is not sure why that is; perhaps sunny conditions put runners in a better mood, he suggested.
Then there is the issue of cramping, that often excruciating, spasmodic, involuntary contraction of muscles that can occur during or, more often, just after a marathon. It almost always involves the muscles that were used to run — the hamstrings or calf muscles, for example. And it can last a minute or two — or much longer.
Conventional wisdom says cramps are caused by dehydration and that the solution is to consume salt and drink more fluids. Not true, says Martin P. Schwellnus, a professor of sports medicine at the University of Cape Town in South Africa.
At the conference in Chicago last month, he reported that he could find no relationship between dehydration and cramping. He has studied cyclists, marathoners and triathletes, measuring levels of electrolytes and body-weight changes, both of which are indicators of dehydration. Those who cramped were no different from those who did not.
Two other studies looked at how much weight ultramarathon runners and triathletes lost during races — a measure of fluid loss and a direct indicator of dehydration. Those who cramped lost no more weight than those who did not. If anything, Schwellnus said, those who did not have cramps were slightly more dehydrated.
The cause of cramps, Schwellnus believes, is an alteration in the electrical signals going to exhausted muscles so that the balance between those signals activating muscles and those inhibiting them is distorted. One way to protect yourself is with proper marathon training and proper pacing. “Racing at too high of an intensity is one of the single most important risk factors,” Schwellnus said.
When muscles cramp, there is a simple and effective treatment: stop running and stretch that muscle. And, Schwellnus said, realize that the cramping will soon stop.
“Almost no matter what you do, if you stop the activity, the muscle will come back to normal,” he said.
Beyond the finish line of every marathon are runners who feel dizzy, and some of them collapse. It is not as common as muscle cramps, but the condition can afflict up to about 5 percent of marathon runners, said Michael N. Sawka, head of the thermal and mountain medicine division at the United States Army Research Institute of Environmental Medicine. He wondered whether the cause could be dehydration, a commonly evoked mechanism.
Sawka looked at published studies. One compared 45 athletes who collapsed after an ultramarathon to 65 who completed the race and did not collapse. There were no obvious differences between the two groups: their body temperatures were the same (dehydration makes the temperature rise), as were their electrolyte levels. But those who collapsed were pushing themselves as hard as they could, were at or close to their personal records, or were medal winners in the race. Perhaps, Sawka said, “that final effort might contribute to collapse.”
The actual cause, though, does not appear to be dehydration, Sawka said. Instead, it is a pooling of blood in the lower legs and feet when vigorous exercise suddenly stops and the heart rate slows markedly.
Timothy Noakes, a professor of exercise and sports science at the University of Cape Town, said he had stopped giving intravenous fluids to collapsed runners.
“We completely changed the way we treat patients,” Noakes said. “All we do is have them lie down and put their feet higher than their head.”
Postmarathon collapse, Noakes added, “is a benign condition.”
“Just lift their legs and you will help the majority of patients,” he said. “That’s all you need to do to make most people recover very, very quickly. You can infuse as much fluid as you want, and you will not get the same response.”
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Exercise may cut risk of various cancers
August 2, 2009
Filed under News
By Amy Norton
NEW YORK (Reuters Health) – Adults who are regularly active, whether through exercise or work, are less likely to develop a range of cancers, a new study suggests.
The study, which followed nearly 80,000 Japanese adults for up to a decade, found that regularly active men and women had lower risks of developing any type of cancer. When the researchers looked at specific types of cancer, they found that exercise was linked to lower risks of colon, liver, pancreatic and stomach cancers.
They also found that the protective effect was strongest among normal-weight men and women — supporting the theory that physical activity helps lower cancer risk at least partly through better weight control.
Dr. Manami Inoue and colleagues at Japan’s National Cancer Center, in Tokyo, report the findings in the American Journal of Epidemiology.
The researchers followed cancer incidence rates among 79,771 men and women who were between the ages of 45 and 74 at the outset. Between 1995 and 1999, study participants were surveyed about their physical activity levels, diet and other lifestyle habits; the researchers then followed them through 2004, documenting more than 4,300 new cancer diagnoses.
Overall, according to the researchers, the risk of developing any cancer dipped slightly as participants’ activity levels climbed. On average, the most-active men were 13 percent less likely than the least active men to develop cancer; the most-active women had a 16 percent lower cancer risk than their sedentary counterparts.
The link held true when the researchers accounted for a range of other factors, including participants’ age, weight, smoking habits, daily calorie intake.
Physical activity was defined not only as leisure-time exercise, but also the amount of time participants typically spent walking, doing physical labor and housework.
"Our results suggest that increased daily total physical activity — not only exercise — may be beneficial in preventing the development of cancer among Japanese men and women," Inoue told Reuters Health.
The researcher also pointed out that Japan’s population is a relatively lean one and that the relationship between physical activity and lower cancer risk was weaker among overweight study participants.
It’s thought that exercise may help prevent cancer, in part, by controlling body fat. But physical activity also has other effects that could theoretically stave off cancer, Inoue and colleagues point out.
Exercise can, for example, stimulate immune system activity, one of the body’s natural defenses against cancer. It may also alter levels of certain hormones, including sex hormones and insulin-like growth factors, which can feed the growth and spread of tumors.
SOURCE: American Journal of Epidemiology, August 15, 2008.
Coffee Lessens the Pain of Exercise
July 27, 2009
Filed under Diet & Fitness, Diet And Nutrition, Running
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| Former competitive cyclist Robert Motl, now a professor of kinesiology and community health, is studying the effects of caffeine on pain during exercise. Credit: L. Brian Stauffer | |
| By LiveScience Staff |
That cup of coffee that many gym rats, bikers and runners swill before a workout does more than energize them. It kills some of the pain of athletic exertion, a new study suggests. And it works regardless of whether a person already had a coffee habit or not.
Caffeine works on a system in the brain and spinal cord (the adenosine neuromodulatory system) that is heavily involved in pain processing, says University of Illinois kinesiology and community health professor Robert Motl. And since caffeine blocks adenosine, the biochemical that plays an important role in energy transfer and thus exercise, he speculated that it could reduce pain.
So the researcher, a former competitive cyclist, divided 25 fit, college-aged males into two distinct groups: subjects whose everyday caffeine consumption was extremely low to non-existent, and those with an average caffeine intake of about 400 milligrams a day, the equivalent of three to four cups of coffee.
Unexpected results
After completing an initial exercise test in the lab on a stationary bike to determine maximal oxygen consumption or aerobic power, subjects returned for two monitored high-intensity, 30-minute exercise sessions.
An hour prior to each session, cyclists — who had been instructed not to consume caffeine during the prior 24-hour period — were given a pill. On one occasion, it contained a dose of caffeine measuring 5 milligrams per kilogram of body weight (equivalent to two to three cups of coffee); the other time, they received a placebo.
During both exercise periods, subjects’ perceptions of quadriceps muscle pain was recorded at regular intervals, along with data on oxygen consumption, heart rate and work rate.
"What we saw is something we didn’t expect," Motl said. "Caffeine-naïve individuals and habitual users have the same amount of reduction in pain during exercise after caffeine (consumption)."
The results are detailed in the April edition of the International Journal of Sport Nutrition and Exercise Metabolism. Co-authors included Steven P. Broglio of the University of Illinois and Sigurbjorn A. Arngrimsson of the Center for Sport and Health Sciences, Iceland University of Education.
"Clearly, if you regularly consume caffeine, you have to have more to have that bigger, mental-energy effect," Motl said. "But the tolerance effect is not ubiquitous across all stimuli. Even brain metabolism doesn’t show this tolerance-type effect. That is, with individuals who are habitual users versus non-habitual users, if you give them caffeine and do brain imaging, the activation is identical. It’s really interesting why some processes show tolerance and others don’t."
Regarding the outcome of the current research, he said, it may be that tolerance to caffeine plays no role in the way it diminishes pain during exercise.
Motl said one of the next logical steps for his research team would be to conduct studies with rodents in order to better understand the biological mechanism for caffeine in reducing pain.
"If we can get at the biological mechanism, we can begin to understand why there may or may not be this kind of tolerance."
Will it help you win?
Motl previously has conducted other studies on the relationship between physical activity and caffeine, and considered such variables as exercise intensity, dose of caffeine, anxiety sensitivity and gender. A future research direction might be to determine caffeine’s effect on sport performance.
"We’ve shown that caffeine reduces pain reliably, consistently during cycling, across different intensities, across different people, different characteristics. But does that reduction in pain translate into an improvement in sport performance?" he said.
Meanwhile, the current research could prove encouraging for a range of people, including the average person who wants to become more physically active to realize the health benefits.
"One of the things that may be a practical application, is if you go to the gym and you exercise and it hurts, you may be prone to stop doing that because pain is an aversive stimulus that tells you to withdraw," Motl said. "So if we could give people a little caffeine and reduce the amount of pain they’re experiencing, maybe that would help them stick with that exercise."
That Little Voice Inside Your Twinge
July 3, 2009
Filed under News
Turns out it’s not so obvious.
Deena Kastor, the American record holder for the marathon, interprets the advice selectively.
“Running isn’t always comfortable,” she said. “I remember running through a lot of discomfort and pain.”
And, Ms. Kastor added, she also runs when she does not feel like it.
“So many times the alarm goes off in the morning and you tell yourself you are too tired,” she said. “There are times when you are unmotivated, you don’t feel your best and most accomplished.”
But if you ignore those messages from your body and just go out and run or do your sport, she said, “those are the days when we have the most pride.”
“The trick in listening to your body is to know what you can run through,” she said. “If you have a sharp pain you should take care of it.”
So does listening to your body mean learning to understand the difference between a pain that signals a serious injury and one that can be ignored? And if it does, why do athletes like Ms. Kastor become seriously injured, anyway?
Last year she broke her foot three miles into the marathon at the Beijing Olympics. In that same race, Paula Radcliffe, who holds the world record in the women’s marathon, ran less than her best because her training was interrupted by a stress fracture that had set her back for months.
MAYBE the problem is that it is hard to understand what your body is saying.
“ ‘Listen to your body’ is always a tough one,” said Keith Hanson, a coach who directs the Hansons-Brooks Distance Project, which recruits talented distance runners and supports them while they train full time.
One of his runners, Brian Sell, was in the Beijing Olympics, and others are internationally competitive.
“There are several aches and pains that you can run through,” Mr. Hanson said, “and others that need some down time. I always try to follow one key rule: If you are gimping — altering your gait— after 10 minutes of running, then it is an injury and not just an ache or pain. You should never run through injuries. If you do, they almost always turn into compensation injuries. What started as an ankle pain becomes knee and hip problems.”
But sometimes even when you have a bad feeling about sudden pain, it can be hard to stop, especially during a race.
That happened to my friend Rafael Escandon, a researcher at a small biotech company in San Francisco. It was 2002, and he had decided to run the Twin Cities Marathon. He had run a few dozen marathons before, so he was hardly a beginner. He knew that the trick was to keep going during those stretches when you feel bad.
The race started well. Mr. Escandon had been training by running eight-minute miles but now, he said, he was going much faster, and it all seemed effortless. “It was all I could do to maintain a 7:40 pace, which felt like I was crawling,” he said.
Then, just after he passed the 17-mile point in the 26.2 mile race, he felt something awful just below his left calf. “It honestly felt like someone had taken a knife and cut my skin,” he said. “I hobbled over to a tree and attempted to stretch my calf for 10 minutes or so.
The pain got worse as he stretched, and even though it diminished when he wasn’t stretching, he still felt as if he had been cut. But dropping out of the race was not an option: he had never quit a marathon.
So, he said, he limped along for nine miles and finally crossed the finish line. Then he showered, took some ibuprofen and rushed to the airport to fly to Europe for a business trip.
When the plane landed, Mr. Escandon got out of his seat and, he said, was immediately “blinded by pain in my left leg.” It hurt so much he could not stand.
He eventually set off, slowly, “whimpering audibly,” he said, as he hobbled to his connecting gate.
Sweating, jet-lagged and still whimpering, he pulled up the leg of his jeans to take a look at his injury. “I was shocked at what I saw,” he said. “The medial side of my leg was grotesquely streaked in purple-black from the bottom of my calf to my ankle, including the top of my foot.”
It turned out that he had torn the muscle under his calf. For weeks afterward, the pain woke him at night. He could not run for three months, and even when he started again the best he could do for six months was a few miles on a treadmill.
“I should have listened to my body,” Mr. Escandon said. “It wasn’t just talking to me; it was screaming at me.”
On the other hand, there is also a different interpretation of “listen to your body.” It’s one favored by Asker Jeukendrup, the director of the Human Performance Laboratory at the University of Birmingham, in England, and an ironman triathlete.
Listening, he said, means that you are supposed to listen for “valuable information” and learn to disregard “other negative information that may come into your thoughts that is actually irrelevant.”
Dismiss, for example, “some niggles, some feelings of fatigue,” he said.
The goal is to push your body to its limits, but not beyond. Easier said than done, he admitted. And, he added, not everyone can do it.
ACTUALLY, said Tom Fleming, my coach, it is unlikely that anyone can do it. Mr. Fleming won the New York City Marathon twice and has coached athletes ranging from adolescents to college and nationally ranked runners. He knows from his days as a competitive distance runner how hard it is to decide when to slow down, when to rest, when to push hard through discomfort or pain.
“I never listened to my body,” he said. “Maybe I should have. So let’s get that clear right off: I think it’s an impossible task.”
When he was training, Mr. Fleming said, he couldn’t train less or make himself go more slowly. And, he added, if you really listen to your body, you will not achieve what you are capable of.
Athletes need someone else, a coach if possible, he said, to tell them when to rest, when to take an easy day and when to work hard.
Another of my colleagues at The Times, Charlie Competello, said he tries to figure out his body’s signals for himself. But he struggles, arguing with himself about what his body is telling him. He thinks of his internal arguments as a debate between “Charlie” and “Charles.” They argue in the mornings, when he plans to go out for runs.
“ ‘Charlie’ says, ‘I’m tired and I’m not going to go out,’ ” he said. “ ‘Charles’ says: ‘No, no, no, you can make it. Go out and do it.’ ”
Usually, he said, Charles wins. He runs and is glad he did.
But the personas also argue in the evening about tempting food, like cake.
Charles says, “Don’t do it.” Charlie says, “Go ahead.”
And, in the evening, Charlie can be the winner. “For some reason, I’m a better person in the morning,” he said.
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