Most experts recommend 1,300 mg of calcium a day for girls aged 9 through 19. Natural sources of calcium, such as low-fat dairy products, are the smartest choice, because they also contain vitamin D and protein, both required for calcium absorption. Milk, yogurt, and cheese contribute most of the calcium in our diets. Some vegetables are also good sources, including broccoli, kale, and Chinese cabbage. Many foods are supplemented with calcium, including some brands of orange juice and tofu. The daily intake for Vitamin D is 600 IU per day for most children and healthy adults.
Having the proper footwear is essential for any workout, and for winter runs, that means sneaks with EVA (ethylene vinyl acetate), says Polly de Mille, an exercise physiologist who oversees New York Road Runner's Learning Series for first-time New York City Marathon runners. “Polyurethane tends to get really stiff and cold in the winter, which could increase your risk of injury.” Another important feature is a waterproof and windproof upper: Look for shoes made with Gortex, or wrap your mesh uppers in duct tape to keep feet dry and warm.
Poor nutrition can manifest itself in many ways. The more obvious symptoms of a nutritional deficiency include dull, dry or shedding hair; red, dry, pale or dull eyes; spoon-shaped, brittle or ridged nails; bleeding gums; swollen, red, cracked lips; flaky skin that doesn't heal quickly; swelling in your legs and feet; wasted, weak muscles; memory loss; and fatigue.