Today's Nutrition Tip: Sports Nutrition

Sports nutrition has come a long way since the days of the legendary ancient Olympian Milo of Croton (6th century B.C.), whose daily diet reportedly consisted of 20 pounds of meat, 20 pounds of bread and 18 pints of wine. Scientists, such as George Brooks from UC Berkeley, showed that carbohydrates are the most important fuel at exercise intensities above 65 percent of maximum effort. A 2010 report by the International Olympic Committee concluded that carbohydrate intake should match the demands of training and competition and may vary considerably during different times of the year. Athletes should consume nutrient–rich carbs (fruits, whole grains, etc.) in place of simple sugars with few nutrients. Protein intake for athletes should be approximately 1.2 to 1.7 grams per kilogram bodyweight per day. Consuming extra protein after exercise may promote strength gains and recovery from training but may not be critical if daily protein intake is optimal. Caloric intake should reflect the metabolic demands of the sport. Vitamin D is important for muscle and bone health and is an important dietary consideration for athletes with limited sun exposure. Foods and supplements such as creatine monohydrate, beetroot juice and beta alanine show potential for improving performance. Following a sensible, high-performance diet will make you a better athlete.

(Nutrition Today, 46: 197-202, 2011)

Today's Training Tip: Prevent Muscle Loss

Older adults typically lose muscle mass as they age — a condition called sarcopenia. Muscle loss increases the risk of falls, decreases mobility and reduces tissue area critical for normal blood sugar metabolism. Japanese researchers showed that consuming a protein snack containing 15 grams of protein plus daily light weight training increased lean body mass and muscle cross-sectional area, while reducing body fat in older adults. Combining light exercise with regular protein intake can prevent muscle deterioration during aging.

(Journal Nutritional Science Vitaminology, 57: 233-238, 2011)

Today's Supplement Tip: Beetroot

A St. Louis University study found that beetroot (200 grams containing at least 500 milligrams of nitrate) improved running speed during a 5-kilometer treadmill speed test in recreational runners. Beetroot juice contains nitrate that the blood vessels use to produce nitric oxide— a critical chemical that promotes blood flow, improves sexual performance and enhances energy levels. The capacity of the endothelial cells (cells lining the blood vessels) to secrete nitric oxide is an important measure of cardiovascular health and performance. Nitrites from food sources such as processed meats might increase the risk of cancer, so it’s probably best to consume beets rather than foods such as hotdogs or bologna.

(Paper presented at American Dietetic Association Food & Nutrition Conference & Expo, September 24, 2011)

Today's Training Tip: Brown Rice

Last year Muscular Development magazine discussed a Harvard University study that found that people who ate five servings of white rice per week had a 20 percent increased risk of diabetes compared to those who ate less than one serving per month. Eating two or more servings of brown rice per week decreased the risk of diabetes by 11 percent (Arch Int Medicine, 170: 961, 2010). Brown rice contains the outer bran and germ portions of the rice grain, which slows its digestion in the gut. Manufacturing white rice removes these portions, leaving only the starchy interior.

A 16-week study from the Chinese Academy of Sciences found opposite results. Researchers compared the effects of consuming white rice or brown rice (ad libitum; they could eat as much as they wanted) on diabetes risk factors in people with type 2 diabetes. They found no differences between groups in body mass index, waist circumference, blood pressure or measures of blood sugar metabolism. They concluded that consuming brown rice had no effect on metabolic risk factors of diabetes.

Differences between the Harvard and Chinese studies could be due to genetic variations in the metabolic response to diet, cultural differences between test subjects or differences in research design.

(Journal of Nutrition, 141: 1686-1690, 2011)

Today's Training Tip: Spot Reducing

Wouldn’t it be nice if you could target abdominal fat with focused exercises such as crunches or hanging leg raises and make it disappear? Any credible fitness or exercise physiology expert will tell you that spot reducing is impossible— doing hundreds of sit-ups won’t make your abs smaller and more defined. Adipose tissue (fat) and muscle do not share the same blood supply, so exercising muscle gets fat for fuel from adipose tissue throughout the body. However, University of Copenhagen researchers found that fat breakdown was higher in adipose tissue near exercising muscles than in adipose adjacent to resting muscles, so spot reducing might be possible.

(Am J Physiol Endocrinol Metab, 292, E394, 2007).

A six-week study from the University of Southern Illinois University found that high-volume abdominal exercise training had no effect on bodyweight, body fat percentage, abdominal fat percentage, waist circumference or abdominal skinfold measurements. The test subjects increased abdominal endurance capacity substantially. There was no effort during the study to reduce abdominal fat through caloric restriction. The study showed that abdominal exercises without dieting had no effect on abdominal fat. If you want six-pack abs, you have to do a lot more than sit-ups and leg raises.

(Journal Strength Conditioning Research, 25: 2559-2564, 2011)

Today's Health Tip: Kidney Function

Coffee is the world's most popular beverage (after water). In the past, coffee drinking was thought unhealthy because it increased heart rate and triggered sleep disturbances in some people. More recent studies have found that coffee drinking helps prevent type 2 diabetes and cardiovascular diseases. Japanese researchers found that it also improved kidney function. They compared urine output in young adults who drank either coffee or green tea. Coffee drinking increased adiponectin, an important chemical in fat and carbohydrate metabolism, and boosted magnesium levels. The study showed that coffee has a positive effect on kidney function.

(Journal Nutrition Metabolism, Published Online July 21, 2011)

Today's Drug Tip: Infertility

Hormone levels are controlled much like the thermostat in your house regulates temperature. When the body detects excessive levels of a hormone, it decreases production. Likewise, it increases production when it senses low levels of the hormone. Testosterone is controlled by a negative feedback loop that includes testosterone release by the testes, gonadotropin-releasing hormone production by the hypothalamus, and LH and FSH release by the pituitary gland. When athletes use anabolic steroids, the body determines that testosterone levels are excessive and shuts down normal production. This affects testosterone metabolism and associated factors such as sperm production and sex drive. Also, high levels of testosterone or anabolic steroids are converted to estrogens, which also affect sexual function. Athletes who use anabolic steroids for long periods typically experience impaired reproductive function. Don’t depend on this! The world is full of accidental babies created when athletes thought they were safe.

(British Journal Of Urology International, published online June 17, 2011; Fertility Sterility 96: 7-8, 2011)

Today's Supplement Tip: Muscle Damage

Eccentric exercise (lengthening muscle contractions) is associated with muscle damage and delayed onset muscle soreness. During recovery from this type of exercise, the muscles repair damaged tissue and increase in size. Leucine is an essential amino acid that plays an important role in activating biochemical pathways involved in muscle hypertrophy. A study from Appalachian State University found that leucine supplements (250 milligrams per kilogram of bodyweight) ingested 30 minutes before performing high-volume drop jumps and eccentric leg presses did not affect muscle soreness, but helped maintain force output during the days after the workout. Leucine had no effect on post-exercise jump height. The study found that leucine promoted recovery following high-volume eccentric exercise, but the effects were small.

(Amino Acids, published online May 11, 2011)

Today's Sex Tip: Testosterone Gel

Daily application of testosterone gels and creams is popular in men with low testosterone levels who do not like intramuscular injections. A study by scientists from Urology Research Options in Aurora, Colorado found that men with low testosterone levels (less than 300 ng/dL) achieved normal blood testosterone levels after two weeks of applying 2.5 grams per day of the gel (1.62 percent testosterone). Side effects were minimal, and included increases in PSA (prostate-specific antigen) or aggressiveness in less than 10 percent of the patients. Increases in testosterone levels, while clinically significant, were not high enough to improve athletic performance.

(Journal Sexual Medicine, 8: 2079-2089, 2011)

Today's Drug Tip: Growth Hormone

Many bodybuilders and power athletes take growth hormone to increase muscle mass, decrease fat, and improve athletic performance. No well-controlled study has shown that growth hormone is an effective sports supplement. An Australian study funded by the World Anti-Doping Agency (WADA) found that growth hormone, with or without testosterone, increased sprint speed and lean mass and decreased body fat. Growth hormone worked best when combined with testosterone. The beneficial effects disappeared after a six-week washout period. Growth hormone had no effect on maximal oxygen consumption, deadlift, vertical jump, or maximum power. This study used recreational athletes, so the results might not apply to elite performers.

(Annals Internal Medicine, 152: 568-577, 2010)