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are, however, some special considerations that vegetarians and vegans need to be aware of. Though leafy greens like spinach and kale are excellent sources of iron, only about 10 percent of iron from plant sources can actually be absorbed by the body (compared to 18 percent from meat). Female endurance athletes, in particular, are prone to low iron levels, so they may need to consider iron supplements if tests show their levels are low. In addition, a 2010 review in the journal Current Sports Medicine Reports by Joel Fuhrman and Deana Ferreri identified several other micronutrients that vegan and vegetarian athletes may be deficient in. In particular, zinc, vitamin B12, and the omega-3 fatty acid DHA are all crucial for physical performance and are either hard to absorb or hard to get enough of from plant sources, so they recommend taking supplements.

“Clearly,” Fuhrman and Ferreri conclude, “a properly designed vegan (or near-vegan) diet can meet the nutritional demands of a speed and agility athlete, such as tennis, skiing, basketball, track, and soccer, but may not be ideal to maximize growth over 300 lb as a football linebacker.” Scott Jurek might disagree with this conclusion, since he manages to consume up to 8,000 calories a day—but there’s no doubt that such extreme consumption requires a special and perhaps rare dedication. Most of us, though, have no desire to exceed 300 pounds or run for 24 hours at a time, so a well-balanced vegan or vegetarian diet is perfectly capable of meeting our needs.

CHEAT SHEET: NUTRITION AND HYDRATION

• To carbo-load, you can max out your carbohydrate stores with just one day of eating 10 grams of carbohydrate per kilogram of body weight.

• To avoid stomach problems during exercise, avoid high-fiber and high-fat foods in pre-exercise meals and allow at least three hours for digestion.

• Eat as soon as possible after exercise (within at most two hours) to enhance recovery and training gains, aiming for a roughly 4:1 ratio of carbohydrate to protein.

• Losing more than 2 percent of your body weight in fluid is thought to hurt performance, but some scientists now believe that simply drinking when you’re thirsty is sufficient.

• Drinking too much can lead to dangerously low sodium levels (hyponatremia) and possibly death. Don’t drink more than eight ounces every 20 minutes.

• For events lasting longer than an hour or two, consume fluids containing no more than 6 percent carbohydrate and some electrolytes.

• Antioxidants like vitamins C and E may block some of the health effects of exercise and slow post-exercise muscle recovery, though the evidence is still preliminary.

• Probiotics can help ward off respiratory infections and digestive problems, but it’s not yet clear which strains of bacteria are best and how much is required.

• Vitamin D (the sunshine vitamin) is crucial for good health and many people require supplementation, but there’s no evidence that extra vitamin D improves athletic performance if you’re not deficient.

• Training with depleted carbohydrate stores (e.g., before breakfast) can teach your body to burn more fat and store more carbohydrates, but there’s little evidence so far that it boosts performance.

• Studies have found no difference in physiology or results in athletes with vegetarian and non-vegetarian diets, provided that the diets are balanced and include all necessary nutrients.

Chapter 11

Mind and Body

A RESEARCHER IN WALES IS CURRENTLY trying to improve the stationary bike performance of a group of volunteers using a program of vigorous training, 45 to 90 minutes a day, five days a week . . . playing a cognitively challenging computer game. Training the brain, he believes, will translate into improved physical performance. However the results turn out, the fact that such an experiment isn’t simply laughed out of the lab shows how much our understanding of the link between brain and body has changed in the past decade.

For decades, exercise physiology has struggled to pin down the limits of physical performance