"If your primary purpose is to improve your running performance, cross-training does not help you much," says Hirofumi Tanaka, Ph.D, an exercise scientist at the Univeristy of Texas at Austin and author of a review of published studies on cross-training. "There is n important principle in exercise trainng called the 'specificity of training'---that is, exercise you perform in practices needs to be as close as possible to the actual competition."

"We are what we repeatedly do. Excellence, then, is not an act but a habit."
- Aristotle

"Moderate activity is fine. Extreme activity requires more caution and evaluation" ~ Michael Miller, director of preventive cardiology at the UNiversity of Maryland Medical Center.

Amateur marathon runners risk heart trouble
Cardiac abnormalities may last even after race is over, researchers say

Amateur marathon runners who run less than 40 miles per week during training often show signs of cardiac dysfunction after the race and some of these abnormalities may persist for up to a month after they cross the finish line, a study shows.

:Running less than 40 miles per week prior to running a marathon leads to temporary heart muscle weakness and increased pressure in the lung arteries," Dr. Malissa J. Wood told Reuters Health. “Individuals who consistently ran greater than 45 miles per week showed no such signs of damage after completing the marathon.”

The findings are based on a study of 20 amateur athletes who ran the 2003 Boston Marathon and underwent echocardiography (ultrasound imaging of the heart) prior to, immediately after, and about one month after running the 26-mile race.

The number of people participating in endurance sports has increased in the past decade, Wood, from Massachusetts General Hospital and Harvard Medical School, Boston and colleagues note in a their study, published in the European Heart Journal.

In the U.S. alone, nearly 480,000 runners completed a marathon in 2001. And while the benefits of moderate exercise on the heart are well established, the effects of more prolonged exertion are less clear. Some studies have suggested that cardiac dysfunction or “cardiac fatigue” occurs during prolonged exercise.

Problems can linger for up to a month

The series of echocardiographs obtained for the 20 amateur marathoners demonstrated “attenuation” of heart function after the race.

There was evidence of abnormalities in both systolic function (the heart’s pumping ability) and diastolic function (the heart’s ability to relax during beats).

All of the systolic abnormalities normalized fairly quickly, but the diastolic abnormalities persisted for up to one month after the race, indicating an inherent alteration in the heart’s ability to relax, the authors note.

Wood and colleagues emphasize that their results do not pertain to elite athletes; “our group consisted of runners who ran on average less than 40 miles a week during training, a level that is most consistent with the 'average' marathon runner.”

Their study also does not address whether this transient dysfunction damages the heart or if there are any long-term cardiac consequences.

Although free radicals are considered to be "central actors" in most human health problems, of special interest to Dr. Cooper is the link between free radicals and heart disease. Free radicals are seen to be the primary cause of plaque buildup in arteries. They act directly upon low-density lipoproteins (the bad form of cholesterol), changing them into something called foam cells, which in turn clog arteries. This process, Dr. Cooper believes, may explain the untimely death of his friend, marathon runner Jim Fixx, at age 52 from coronary disease.

Research has shown that overexercising can lead to overproduction of free radicals in the body. Because of his extraordinary level of physical exertion, Fixx would have run a much higher risk of free radical damage than the average person. Other free radical stimulants include air pollution, cigarette smoke, ultraviolet light, pesticides, and food contaminants.

"In the 17 years preceding his death," Dr. Cooper notes, "Fixx had run 37,000 miles, including 20 marathons, and he was still running 60 miles per week up to the time of his death. Of course, it could be contended that if Fixx and other highly trained, older athletes had not been involved in marathoning and ultramarathoning, they might have succumbed to their disease many years before.... But increasingly, I have come to believe that there also may be a link between over-training and disease." Dr. Cooper presents other examples of athletes who died young, not from heart disease but from cancer, in which radicals may have played a decisive role. Dr. Cooper also considers his own seemingly inevitable bouts of sickness during marathon training: "I wondered if it was possible that excessive exercise might not only be unnecessary, but might even be harmful - so harmful that my own physical training philosophy and recommendations should be altered."

This new view of exercise naturally has a profound effect on aerobic fitness programs. "It has become clear," Dr. Cooper writes, "that an appropriate exercise prescription becomes more complicated - especially when you take into account exposure to free radical |triggers' such as overtraining."

Overtraining with Caution:
Researchers, including the late Dr. Linus Pauling, have recommended large doses of the antioxidant vitamins C, E, and beta carotene for fighting free radicals, but Dr. Cooper believes vitamins are only part of the story. "What is often overlooked," he notes, "is that exercise must be at the center of any effective antioxidant action plan. Without regular exercise, your body's internal defenses against free radicals - including natural endogenous antioxidants [those produced by the human body], such as SOD, GSH, and catalase, may become too fragile for supplements to have their full effect."

Dr. Cooper's solution to the free-radical problem is The Lower-Intensity Exercise Program, which he calls "the most effective exercise program for good health - including building up defenses against free radicals...." Here, low intensity means exercising several times a week at your "target heart rate," a rate in between your normal heart rate and the maximum rate that allows you to improve your endurance. For easier measurement of exercise duration and intensity, Dr. Cooper devised a point system. One must work up to 15 points each week using one of a variety of exercise choices, including walking, aerobic walking, walk-running, cycling, and swimming. The exercises can be performed on one of two levels. one for those interested only in fitness, and a more strenuous one for athletic competitors.

Specificity of Sport

Training for any sport requires work on a combination of the following factors:
Coordination:
Use your muscles in the same manner you will use them in competition.
Speed:
Use your muscles at the same speed or faster than you will use them in competition.
Strength:
Use your muscles against resistance in the same manner that you will use them in competition.

"I think what I represent is achieving what you want in life. It's a matter of your attitude. Some people have a negative attitude, and that's their disability."
Marla Runyan, legally blind US 1500M Olympic hopeful.