European Stars and Stripes (Newspaper) - October 9, 1990, Darmstadt, Hesse                                To your health what Good is warming up by Sandra Blakeslee new York times stretching touching the toes running in place and otherwise warming up before a vigorous workout improves Range of motion and makes athletes feel better but does virtually nothing to prevent muscle injuries new research suggests. The research involving rabbits has yet to be duplicated in people. But health experts say the findings Are important because More and More people Are exercising and because Little is known about the benefits of warming up. The idea that warming up protects Muscles Quot sounds Good said James a. Schwane an associate professor of health and kinesiology at the University of Texas in Tyler. The researchers Are studying the pain and swelling that occasionally afflict joggers cyclists and other athletes. In most cases they say these symptoms result when certain muscle fibres Are torn in certain kinds of movement. But the tearing does not result from a Lack of oxygen they say and therefore warming up is useless to prevent it. If a sport requires flexibility and a wide Range of motions the warm up can improve performance experts say. And warming up and stretching connective tissue that surrounds Muscles might help prevent soreness that can occur even if Muscles Are not injured. It is not known if warming up prevents injury to ligaments and tendons the researchers said. Physiologists and molecular biologists have Only recently begun to concentrate on muscle injury said or. Richard Lieber associate professor of surgery at the University of California in san Diego. The idea that warming up May not prevent muscle injury is based on the known physical properties of the three a theory of muscle damage scientists Are developing a new understanding of How Muscles function leading them to suspect that warming up before exercise does not protect muscle fibres from injury. A variety of fibres of the three kinds of muscle fiber types 1, 2a and 2b, 2b is most subject to injury. Most experts had believed warmups could prevent injury by increasing the flow of oxygen carrying blood to Muscles. But scientists say 2b fibres do not need oxygen to turn their glucose fuel into Energy. Calcium buildup and damage As the Energy producing bodies called mitochondria Are exhausted in Type 2b fibres they May let Large amounts of Calcium build up activating destructive enzymes. Calcium buildup types of muscle fibres found in most mammals and the three types of contractions that Muscles undergo in performing movement Lieber explained. Type i fibres Are slow to contract and generate Low Levels of Force. They act for example to maintain the body a position while standing. Able to generate most of the Energy they need from glucose and oxygen they Are highly resistant to fatigue. Type 2 fibres contract rapidly generating up to four times As much Force As Type i fibres. They come in two varieties. Type 2a fibres also use oxygen to make Energy and can perform Large amounts of work before fatigue sets in. Type 2b fibres Are the Quot biggest strongest and most rarely used muscle fibres a he said. But instead of using oxygen to make Energy they rely on a More primitive but faster process called Glycolysis which turns glucose directly into Energy without using oxygen. They produce Large amounts of Force quickly he said but fatigue rapidly. Sources Richard l. Lieber. . Rebecca Chamberlain new York times Lieber and his swedish colleague or. Jan Frieden studied All three muscle cell types in experiments on rabbits whose leg Muscles were mechanically lengthened contracted and both lengthened and contracted. Then rabbits were killed and their leg muscle fibres were examined closely. Although the rabbits had not done any Quot warming up Quot the Type 1 and 2a fibres were Normal after All three treatments or. Lieber said. But after the lengthening contracting Experiment the Type 2b fibres were destroyed. Their cell Walls had broken and enzymes the cells had then produced had begun to consume the cell itself. This is the kind of injury that produces the pain and swelling some athletes feel after exercise. Why the cells fall apart is not yet fully understood. After the first few minutes of extreme exercise he said Type 2b fibres Are depleted of Energy become stiff and As they continue to be stretched May experience mechanical  Joy a special kind of Calm by Ira Dreyfuss associated press it s amazing How anything that feels so bad can make you feel so Good. After 30 minutes of gasping sweating and aching you re enjoying the Post exercise Coo Down a and it is really Cool. As you catch your breath and walk you feel As Serene As a sunny Day. A quiet Joy washes Over you. Sometimes it even comes Over you while you re still running. What puzzles researchers is Why. They believe the altered state is cooked out of the biochemical Stew you bring to a simmer by exercising but they re still working out both the ingredients and the recipe. Back during the running revolution of the 1970s, the feeling was described As Quot runner s High Quot probably a borrowing from the drug culture Quot High a said Murray e. Allen associate professor in the school of kinesiology the study of muscle movement at Simon Fraser University Burnaby British Columbia. Allen and other researchers consider the term inaccurate. The feeling is not solely for runners of course a the mood change has been reported from Many activities. And studies indicate its really a kind of Calm he said. Researchers looking for the physiological cause have been focusing on Beta endorphin one of a class of hormones that May act As opiates. When exercise increases stress Beta endorphin production also increases often sharply. Endorphins seem to partially control the effects of the hormone epinephrine the biochemical accelerator in the body a reaction to stress said Peter a. Farrell an associate professor of applied physiology at Pennsylvania state University. A i firmly believe. Endorphins Are keeping the body from Over responding Quot he said. Quot a Calm is one Label you could hang on it Quot said Bradley d. Hatfield associate professor in the department of kinesiology at the University of Maryland who is analysing the relationship of mood and Beta endorphin Levels. Some findings from that project have been reported in the journal Medicine and science in sports and exercise. The researchers had 12 Young men exercise at varying intensities on stationary bikes. They found that Beta endorphin Levels increased with intensity and that the Levels declined More slowly among the higher intensity exercisers after the workout was Over. But endorphin increases do not translate consistently into mood changes. Exercisers and non exercisers reported lower anxiety and stress. This could mean that people Felt More comfortable As time passed and they got More used to the conditions of the Experiment Hatfield said. Depression and hostility scores did t change but that could be because these Young healthy people did no to have much depression or hostility to begin with he said. Quot it s probably a multidimensional thing Quot Hatfield said. Mood could be affected by everything from the complexities of Neur chemistry to the simple feeling of Success you get from doing a Tough Job he said. Page 16 a a a the stars and stripes tuesday october 9,1990