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2001 Nutrition and Health News from ACSM

At this year's meeting of the American College of Sports Medicine (ACSM, the nation's leading group of sports medicine professionals), over 5,000 members gathered in Baltimore to learn the latest research regarding health, exercise and sports medicine. The following are some highlights that might be of interest to you.

IMPORTANCE OF EXERCISE
We all know that exercise is health-protective, but just how much does exercise impact health? One study with about 26,000 men indicates those who exercised had lower rates of death from cancer than those who exercised less. This held true even for smokers. If you have friends who smoke, tell them to at least exercise and be fit!

Exercise can save corporations millions of dollars on medical expenses. In a three-year study of the effectiveness of a corporate wellness challenge, 700 employees earned points for doing regular exercise, reducing cholesterol levels, body fat and blood pressure plus attending health education programs. The employees got paid $350 per person for completing the program. Incentive payouts of $400,000 yielded net savings of $1.6 million for the three year period ($762 per participant per year). The program contributed to reduced health care costs, less absenteeism and reduced workers compensation costs. Exercise is less expensive than medicine!

One "innovative" way to become fit is to get a dog and walk it. But even dog owners need guidelines. A survey of 410 dog owners suggest 58% did not walk their dogs regularly, and only 22% walked their dogs for more than 2 hours per week--not long enough! This lack of exercise has implications for the health of both the dog and the owner. Fido, start begging to go for a walk!

CANCER
The benefits of exercise extend into cancer recovery. Chemotherapy and radiation treatment are known to cause fatigue and reduced physical activity, as well as reduced immune function. In a study with 11 breast cancer patients who did strength training (1-3 sets) and aerobic exercise (15-20 minutes) for three months after radiation treatment, the women showed improved immune function (as measured by recovery of lymphocytes).

Exercise has psychological benefits as well for cancer patients. In another study of 40 women in recovery from breast cancer, those who walked regularly experienced less body dissatisfaction and physique anxiety; they felt better about their bodies and reported improved health-related quality of life. Integrating physical activity into cancer treatment programs has meaningful implications.

FLUIDS
If you lose 2-3% of your body weight pre-post exercise, you compromise your ability to perform at your best. Yet, many athletes fail to drink enough fluids. In a simulated 10 mile running race, the athletes drank only 30% of what they lost via sweat and became 2% dehydrated. This study underscores the need to adhere to a predetermined fluid schedule. By knowing your sweat rate (as determined by weighing yourself naked before and after exercise), you can then know how much to drink. Theoretically, if you lose 1 pound of sweat per hour of exercise, you should target consuming 1 pound of fluid (16 ounces) per hour during your next exercise bouts. In reality, you may not need/be able to tolerate quite that much because your body has inner water that gets released during exercise--about 3 grams water become available /gram muscle glycogen used during exercise--but at least you'll have a baseline fluid target. By experimenting during training, you can learn how much fluid you can actually tolerate during exercise in different temperatures.

A survey of almost 250 collegiate athletes at U Mass-Amherst indicates that prior to exercise, 13% of the athletes were considered underhydrated (based on the concentration of their urine). Sixty-nine percent were acceptably hydrated, and only 17% were well hydrated. Men were more likely than women to be underhydrated. The bottom line: Be responsible--consume enough fluids!

Exercise scientists have validated that an accurate way to tell if you have had enough fluids is to simply monitor the color of your urine. The darker the color, the greater the level of dehydration. In a 30 mile mountain bike race (completed with no fluids other than "tanking up" beforehand), the athletes ended with a very small volume of dark-colored urine that was indicative of 5% dehydration.

Overhydration also deserves mention. Among "slow athletes" (such as participants in >5-hour fund-raising marathons), medics are noticing more and more disoriented participants with a vacant stare. The problem: overhydration. These slow athletes take the advice "drink often" to the extreme. Hints: 1. Do not add water to a sloshing stomach. 2. Consume sodium-containing sports drinks and foods (as compared to consuming only water).

As for what's acceptable to drink during exercise, a study with ever-popular Coca Cola validated what athletes have been doing for years. Cyclists traded sports drink for Coke after 1.5-2 hours of hard biking and again during the final 30-minute sprint. They enjoyed a stronger performance than when they had no caffeine. The combination of caffeine + sugary fluid (be it Coke or a sports drink + caffeine) yielded a stronger finish.

BODY FAT / WEIGHT
Weight is forever a concern of athletes, and overweight / obesity is a national public health concern. Researchers are particularly interested in the effect of exercise on weight management. Overweight people commonly believe they have to exercise vigorously to achieve weight loss. In a 16 week study with overweight people assigned to one of 3 programs (diet plus: vigorous exercise OR intermittent 10-minute bouts of vigorous exercise OR simply increased activity in their daily lifestyle), the subjects averaged 1 lb. weight loss / week and all experienced similar health benefits (reduced blood pressure, blood lipids). The bottom line: Simple daily activity has a positive impact on weight and health. Not everyone wants to exercise vigorously (nor needs to exercise vigorously). But most of us can park the car further away, take more stairs and fewer elevators, and sweep the kitchen floor with more effort. Small bouts of activity count; they burn calories and improve health.

Take heed: Doing regular exercise does not always equate to weight loss. In a 16 month study, overweight women who exercised 5 days/week for 45 minutes did not lose weight (but they did improve fitness). The women failed to create the calorie deficit needed to lose body fat. Apparently they were less active during other parts of the day.

Nancy Clark, MS, RD specializes in nutrition for sports and exercise. She counsels both competitive and casual exercisers at SportsMedicine Associates in Brookline MA (617-739-2003). Her popular book, Nancy Clark's Sports Nutrition Guidebook, Second Edition, is available via www.nancyclarkrd.com.