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High-Impact Exercise Strengthens Bones

Three recent studies show that the single most important factor that helps prevent osteoporosis is intense resistance exercise.

1) A review of 10 studies shows that the higher the level of competitive sports, the greater the bone density of female collegiate athletes (J Am Board Fam Med, November 2011;24:728 - 34). As the competition becomes more intense and requires more training, the greater force in training causes bones to become larger and stronger, with elite athletes having the highest bone mineral densities.

2) Adolescent male athletes have much denser bones than non-athletes (J Strength Cond Res, November 11, 2011). Those competing in the high-impact sports have the densest bones. The high-impact sports were gymnastics, basketball, and handball.

3) Men and women who participate in high-impact sports at the ages when bones grow the most (10 to 30 years) gain the most bone, according to a review of the scientific literature reported in Physical Medicine and Rehabilitation (September, 2011;3(9):861-7). Those who continue in these sports maintain bone density.

High-impact sports include gymnastics, hurdling, judo, karate, volleyball and other jumping sports, soccer, basketball, racquet games, step-aerobics, and speed skating. Repetitive low-impact sports (such as distance running) are also associated with greater bone density. Non-impact sports such as swimming, water polo and cycling have not been shown to improve bone density.


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Neck Cooling Helps You Go Faster in Hot Weather

Placing a cooling band on the neck before the start of a 90-minute time trial helps you run faster in hot weather (Medicine and Science in Sports and Exercise, December 2011; 43(12):2388-2395). Replacing the cooling neck band every 30 minutes offered no additional benefit.

More than 80 percent of the energy used to power your muscles is lost as heat, so during intense exercise in the heat, body temperature rises. This slows you down as the limiting factor to how fast you can run is the time it takes to bring oxygen into muscles through the bloodstream. A rise in body temperature increases the amount of oxygen your muscles need and slows you down.

Dropping your body temperature before you compete has been shown in many studies to help you run faster. This can be done by cooling yourself in water before competition, using a cooling vest or putting a cooling band around your neck.

Cooling the head and neck are far more effective in helping you run or ride faster than cooling comparable amounts of skin anywhere else in your body (J Applied physiology, 1976;40:668-72). Cooling is more effective if it is sustained after a person starts racing (Proceedings from the Australian Physiological and Pharmacological Society, 2001;32:122P).

Cooling the brain improves racing times. Brain function is an important part of how fast a person can race. During intense exercise, the muscles build up huge amounts of lactic acid that spill over into the bloodstream and travel to the brain. The brain uses lactic acid as its most efficient fuel since lactic acid can be used for energy and requires the least amount of oxygen of all sources of energy. Cooling the brain allows the brain to meet its needs for energy and allows you to run faster.

In this study, the neck band lowered neck skin temperature, but it did not lower body temperature, fluid loss, or sugar and lactic acid levels; and it did not affect the stress hormones, dopamine and serotonin.

The neck-cooling band is a long skinny beanbag filled with water-absorbing pellets (found in garden centers). Once soaked in water, it will stay wet for a very long time. You can make one yourself or order from for $10.00 plus $1.50 USPS first class shipping (USA).


New Study on L-Arginine

A recent paper from the University of Alberta shows that the popular supplement, L-arginine, probably offers no advantage for athletic competition (Applied Physiology, Nutrition and Metabolism, 2011, 36(3): 405-411).

HOW ARGININE MAY IMPROVE PERFORMANCE: Arginine is an amino acid, a protein building block. In the body, arginine is converted to NITRIC OXIDE which opens blood vessels to increase the flow of blood to muscles. Theoretically, this could bring more oxygen to muscles and help you to ride faster. It also increases blood levels of GROWTH HORMONE that helps muscles recover faster from hard exercise. Growth hormone also raises blood levels of INSULIN AND INSULIN-LIKE GROWTH FACTOR-1 that help muscles grow.

WHY ARGININE MAY NOT IMPROVE PERFORMANCE: Most of the studies that show these benefits have been done on non-athletes. Arginine is usually given to people who have heart trouble and high blood pressure. The few studies done on competitive athletes show conflicting results, which could be due to the fact that nobody knows how much arginine to take to improve performance.

WHY THIS STUDY IS DIFFERENT FROM ALL OTHERS: The authors gave high doses (0.15 g/kg body weight), very low doses (.075 g/kg of body weight), and placebo (no arginine) successively to fit, healthy young men at rest. Blood was drawn every half hour for three hours after each dose. The authors knew that arginine disappears from the bloodstream two hours after it is taken.

In these healthy young men, both the high and low doses of arginine raised blood arginine levels equally, and did not raise nitric oxide, growth hormone, insulin, or insulin-like growth factor-1. The author concluded that arginine may benefit older sick people, but it may have little effect on healthy young men. The author has repeated these studies on endurance and strength-trained athletes but has not reported his findings.


Recipe of the Week:

French Lentil Soup

You'll find lots of recipes and helpful tips in The Good Food Book - it's FREE ***********************************************

December 4th, 2011
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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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