There were a number of articles in the news recently detailing the fact that the amount of exercise needed to improve health, is modest, and more is not necessarily better, with too much exercise potentially leading to health complication. The studies mostly focused on running, but the implications should carry over to other sports also. Perhaps exercise should be likened to the to the benefits of red wine, with the most benefits when taken in moderation. Researchers at the University of South Carolina Arnold School of Public Health and other institutions combed through the health records of 52,656 American adults who’d undergone physicals between 1971 and 2002 as part of the Aerobics Center Longitudinal Study at the Cooper Institute in Dallas. Each participant completed physical testing and activity questionnaires and returned for at least one follow-up visit.
The researchers found that about 27 percent of the participants reported regularly running, although in wildly varying amounts and paces. The scientists then checked death reports. Over the course of the study, 2,984 of the participants died. But the incidence was much lower among the group that ran. Those participants had, on average, a 19 percent lower risk of dying from any cause than non-runners.
Notably, in closely parsing the participants’ self-reported activities, the researchers found that running in moderation provided the most benefits. Those who ran 1 to 20 miles per week at an average pace of about 10 or 11 minutes per mile — in other words, jogging — reduced their risk of dying during the study more effectively than those who didn’t run, those (admittedly few) who ran more than 20 miles a week, and those who typically ran at a pace swifter than seven miles an hour.
His analysis echoes the results of another new examination of activity and mortality, in which Danish scientists used 27 years’ worth of data collected for the continuing Copenhagen City Heart Study. They reported that those Danes who spent one to two and a half hours per week jogging at a “slow or average pace” during the study period had longer life spans than their more sedentary peers and than those who ran at a faster pace.
This decidedly modest amount of exercise led to an increase of, on average, 6.2 years in the life span of male joggers and 5.6 years in women.
“The relationship appears much like alcohol intakes,” he continued. “Mortality is lower in people reporting moderate jogging than in non-joggers or those undertaking extreme levels of exercise.”
There’s further confirmation of that idea in the findings of a large study of exercise habits om the Lancet which showed that among a group of 416,175 Korean adults, 92 minutes a week of moderate exercise, like walking, gentle jogging or cycling, increased life span by about three years and decreased the risk of mortality from any cause by about 14 percent.
In that study, those who embarked on more ambitious exercise programs did gain additional risk reduction, as seems only fair, but the benefits plateaued rapidly. For each further 15 minutes per week of moderate exercise that someone completed beyond the first 92, his or her mortality risk fell, but by only about another 4 percent.
Whether and at what point more exercise becomes counterproductive remains uncertain. “In general, it appears that exercise, like any therapy, results in a bell-shaped curve in terms of response and benefit,” says Dr. James H. O’Keefe, a cardiologist from Saint Luke's Hospital in Kansas City, US.
“To date, the data suggests that walking and light jogging are almost uniformly beneficial for health and do increase life span,” Dr. O’Keefe says. “But with more vigorous or prolonged exercise, the benefits can become questionable.
“I’m a fan of distance running,” he adds. “I run. But after about 45 to 60 minutes a day, you reach a point of diminishing returns, and at some point, you risk toxicity.”Research shows that extreme endurance sports such as marathons, triathlons and long-distance bicycle races can cause structural changes to the heart and large arteries.Usually recovery occurs within a week. But for some individuals, repetitive injury over months and years of training and competition can lead to patches of fibrosis, or scarring, in the heart, say scientists. This can lead to an increased likelihood of potentially fatal abnormal heart rhythms.
Dr James O'Keefe, , who led a review of the evidence, said: "Physical exercise, though not a drug, possesses many traits of a powerful pharmacologic agent. A routine of daily physical activity can be highly effective for prevention and treatment of many diseases, including coronary heart disease, hypertension, heart failure, and obesity.
"However, as with any pharmacologic agent, a safe upper-dose limit potentially exists, beyond which the adverse effects of physical exercise, such as musculoskeletal trauma and cardiovascular stress, may outweigh its benefits." The research is published in the June issue of Mayo Clinic Proceedings.
Endurance sports such as ultramarathon running or professional cycling have been associated with as much as a five-fold increased risk of atrial fibrillation, one kind of abnormal heart rhythm, say the scientists. Excessive sustained exercise may also be linked to coronary artery calcification, and dysfunctional and stiffened large arteries. One study showed that around 12% of apparently healthy marathon runners had signs of heart scarring. Their chances of suffering a heart-disease event was also significantly higher than average.
Komentar
Posting Komentar