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Interval Training

To become stronger and faster, athletes use a technique called interval training, in which they exercise very intensely, rest and then alternate intense bursts of exercise and rest until their muscles start to feel heavy. Intervals are a fixed number of repeats of a fixed distance at a fixed pace with a fixed recovery time. There are two types of intervals: long and short. A short interval takes less than 30 seconds and does not build up significant amounts of lactic acid in the bloodstream, so an athlete can do lots of repeat short intervals in a single workout.

Long intervals take two minutes or more and are very tiring. In interval training, a runner may run a quarter mile 12 times, averaging 1 minute, with a 110-yard slow jog between each. A weightlifter may lift a heavy weight ten times in a row and then repeat another set of ten. Runners run intervals as fast as they can and recover enough to run the same fast pace several times. Runners need very short recoveries between intervals, usually only about 30 seconds; but weight lifters need much longer recoveries, at least two and a half minutes. Runners become short of breath and feel a burning in their muscles when lactic acid starts to accumulate in muscles, but it takes only a few seconds for a trained athlete to recover between each hard run. On the other hand, weight lifters feel burning caused by tearing of the muscle fibers and it takes a much longer time for the pain to disappear so they can lift very heavy weights again.

You can apply the concept of interval training to your program at any level of fitness. When you start a new exercise program, exercise for 30 seconds, stop for 30-60 seconds, longer if you need it. Alternate exercising and resting until you feel tired or your muscles feel heavy. Then stop for the day. The stronger you get in your sport, the more intense your intervals can become. You work at your maximum capacity for 30-60 seconds, then take 60-90 seconds to recover, then go very hard for another 30-60 seconds. Do this vigorous interval workout once a week until you get tired. At first you may only be able to do two or three intervals, but your muscles get stronger and you build up the number of intervals you can complete. Go easy the next day or take a day off if you feel any discomfort.


Dear Dr. Mirkin: Why do runners wear such skimpy shorts, even when it’s cold or rainy?

Heavy clothes slow you down. A heavy sweatsuit weighing 34 ounces will slow a 10 kilometer time by about 45 seconds. Wearing a sweatsuit and a nylon outer shell weighing 47 ounces will add almost six minutes to a marathon time. A lighter running suit weighing 22 ounces will slow you down by about three minutes. To reduce the weight that they carry, some runners even tear the edges off the identifying paper number pinned to their shirts.

The ability of a material to hold water is even more important than its weight. You perspire when you exercise intensely and sweat collects in your clothes, making them a lot heavier. Cotton clothes absorb sweat and keep on gaining weight as you continue to sweat during a competition. On the other hand, synthetic fibers such as polyester do not hold much water, so they remain light. The average competitive runner will run faster by four seconds in a 10-kilometer race and 20 seconds in a marathon just by switching from a cotton T-shirt and shorts weighing 8.2 ounces to nylon ones weighing 5.1 ounces. However, at temperatures below 40 degrees Fahrenheit, you will run faster by wearing clothes to cover your arms, legs, fingers and ears. Shivering will use up far more energy than it takes to carry extra clothes.


Dear Dr. Mirkin: What’s the best time to do stretches?

Stretching should always be done after your muscles are warmed up. Warming up raises muscle temperature to make them more pliable and resistant to injury. Resting muscle temperature is only about 97 degrees, but a slow jog around the block or any similar warm-up activity will raise muscle temperature to more than 99 degrees. Then you can do your stretches, or you can stretch after you finish your workout.

There’s no good evidence that stretching prevents injuries, but stretching that is done properly can help to make you a better athlete. Competitive athletes stretch to make muscles and tendons longer to generate a greater torque about a joint, so they can lift heavier, run faster, jump higher or throw further. Stretch no further than you can hold for a few seconds. Bouncing gives you a longer stretch, but it can tear muscles. Only competitive athletes need to stretch further than they can hold for a few seconds. Forceful stretching will give you greater flexibility than slow deliberate stretching, but it increases your chances of injuring yourself. If you're over 50, be extra careful because older muscles are less springy and more likely to tear.


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Recipe of the Week
Barley is one of my favorite whole grains; it’s inexpensive, familiar and delicious. Try it in this hearty recipe:
Split Pea and Barley Stew

List of Diana's Healthful Recipes


June 26th, 2013
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About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities. Read More
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