Whole Food and Nutrition

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Food and drinks for athletic performance


What an athlete consumes before, during and after exercise is important for comfort and performance during exercise. While eating soon before exercise doesn't provide the bulk of the fuel needed for the activity, it can prevent the distracting symptoms of hunger during exercise. The major source of fuel for active muscles is carbohydrate which gets stored in the muscles as glycogen in the days before exercise. This is one reason that the post-exercise meal is critical to recovery and being ready for the next exercise session. We will start with fluids.

Fluid and Electrolytes to support activity

Water is the main need for the body' life-supporting functions. Water is its number one nutrient. Body functioning is compromised by loss of too much water. Sweat is the obvious manner in which the body loses water. Exhaling leads to loss of water via vapor. During physical exercise, both routes have a purpose, and dehydraytion becomes a a problem. Fatigue is the first symptom of dehydration: a water loss of even 1 to 2 percent of body weight can lessens a person's capacity to do muscular activity. A 7% loss can lead to a likely collapse.

Fluid losses via Sweat

Working muscles produce heat as a by-product of ATP breakdown. The body cools itself via sweating. Each liter of sweat dissipates about 600 kcalories of heat, preventing a rise in body temperature of almost 10 C. The body routes its blood supply through the capilaries just under the skin, and the skin secretes sweat to evaporate and cool the skin and the underlying blood. The deeper body chambers are cooled when the blood flows back.

Hyperthermia

In hot, humid weather, sweat doesn't evaporate well because the surrounding air is already laden with water. Body heat builds up and triggers maximum sweating, without sweat evaporation, little cooling takes place. In such conditions, active people must take precautions to prevent heat stroke. The only way to prevent heat stroke is to drink sufficient fluid before and during the activity, rest in the shade when tired, and wear lightweight clothing that allows evaporation. [Hence the danger of rubber or heavy suits that 'supposedly promote weight loss during physical activity - they promote profuse sweating, prevent sweat evaporation, and invite heat stroke] If you ever experience any of the symptoms of heat stroke listed under Explanations in the left column, stop your activity, sip fluids, seek shade, and ask for help. Heat stroke is dangerous and can be fatal, these symptoms demand attention.

Hypothermia

Endurance athletes can easily lose 1.5 liters or more of fluid during each hour of activity. To prepare for fluid losses, a person must hydrate before activity. To replace fluid losses, the person must rehydrate during and after activity. Even then, in hot weather, the GI tract may not be able to absorb enough to keep up with sweat losses, and some degree of dehydration may be inevitable. Athletes preparing for competition are often advised to drink extra fluids in the days immediately beforehand, especially if they are still training. The extra water is not stored in the body, but drinking extra water ensures maximum hydration at the start of an event. Some coaches and athletes withold water during practice because they mistakenly believe the body adapts to use less water and that this will somehow be beneficial. This false and dangerous idea has cost some athletes their health, and some their lives. [as well as poor performances] Full hydration is imperative for every athlete both in training and in competition. The athlete who arrives at an event even slightly dehydrated, arrives with a disadvantage. Drinking extra water does no harm and may be protective. What is the best fluid for an exercisng body? For noncompetitive, everyday active people, plain cool water is recommended, especially in warm weather, for two reasons: it rapidly leaves the digestive tract to enter the tissues where it is needed, and it cools the body from the inside out. For endurance athletes, other purposes for replenishing water lost through sweating and providing a source of carbohydrate to supplement the body's limited glycogen stores. Carbohydrate depletion brings on fatigue in the athlete, but as already mentioned, fluid loss and the accompanying buildup of body heat can be life-threatening. Thus the first priority for endurance athletes should be to replace fluids. Many good-tasting drinks are marketed for active people.

Electrolyte losses and replacement

When a person sweats, small amounts of electrolytes - the electrically charged minerals soduim, potassuim, cholride, and magnesium - are lost from the body along with water. Losses are greatest in beginners; training improves electrolyte retention. To replenish lost electrolytes, a person ordinarily needs only to eat a regular diet that meets energy and nutrient needs. In extremely demanding endurance events lasting more than 3 hours, electrolyte replacements may be needed. Electrolyte or salt tablets always cause water to flow out the tissues into the GI tract, they also increase potassium losses, irritate the stomach, and cause vomiting. Thus these tablets worsen dehydration and impair performance in several ways.

When To Eat

Exercising on a full stomach is not ideal. Food that remains in your stomach during an event may cause stomach upset, nausea, and cramping. To make sure you have enough energy, yet reduce stomach discomfort, you should allow a meal to fully digest before the start of the event. This generally takes 1 to 4 hours, depending upon what and how much you've eaten. Everyone is a bit different, and you should experiment prior to workouts to determine what works best for you. If you have an early morning race or workout, it's best to get up early enough to eat your pre-exercise meal. If not, you should try to eat or drink something easily digestible about 20 to 30 minutes before the event. The closer you are to the time of your event, the less you should eat. You can have a liquid meal closer to your event than a solid meal because your stomach digests liquids faster.

What To Eat

Because glucose is the preferred energy source for most exercise, a pre-exercise meal should include foods that are high in carbohydrates and easy to digest. This include foods such as whole wheat pasta, breads, fruits, energy bars and drinks.

Planning

Planning is essential if you are competing in an all-day event, such as track meets or other tournaments. Consider the time of your event, the amount of your meal and the energy required. Also, be aware of the amount of fluid you consume. You should plan ahead and prepare meals and snacks that you have tried before and know will sit well with you. Do not experiment with something new on the event day.

Suggested Pre-Exercise Foods

Eating before exercise is something only the athlete can determine based upon experience, but some general guidelines include eating a solid meal 4 hours before exercise, a snack or a high carbohydrate energy drink 2 to 3 hours before exercise, and fluid replacement (sports drink) 1 hour before exercise.

1 hour or less before competition

fruit or vegetable juice such as orange, tomato, or V-8, and/or
fresh fruit such as apples, watermelon, peaches, grapes, or oranges and/or
Energy gels
up to 1 1/2 cups of a sports drink.

2 to 3 hours before competition

fresh fruit
fruit or vegetable juices
whole grain bread and bagels
low-fat yogurt
sports drink


3 to 4 hours before competition

fresh fruit
fruit or vegetable juices
whole grain bread and bagels
whole grain pasta with tomato sauce
baked potatoes
energy bar
whole grain cereal with low-fat milk
low-fat yogurt
whole grain toast/bread with real peanut butter, lean meat, or low-fat cheese
30 oz of a sports drink

Sugar and Performance

If you are an endurance athlete, evidence suggests that eating some sugar (like energy bars, some types of candy bars, or sports drinks) 35 to 40 minutes before an event may provide energy (glucose) to your exercising muscles when your other energy stores have dropped to low levels. However, you should experiment with such strategies before competition because some people do not perform well after a blood glucose spike.

Caffeine and Performance

Caffeine acts as a stimulant on the central nervous system. It had been thought to boost endurance by stimulating a greater use of fat for energy, and thereby reserving glycogen in the muscles. Research, however, doesn't support that theory. When caffeine improves endurance, it does so by acting as a stimulant. Caffeine can have serious side effects for some people. Those who are very sensitive to its effects may experience nausea, muscle tremors, and headaches. Too much caffeine is a diuretic, and can result in dehydration, which decreases performance.

Foods to Avoid Before Exercise

Any foods with a lot of fat can be very difficult and slow to digest and remain in the stomach a long time. They also will pull blood into the stomach to aid in digestion, which can cause cramping and discomfort. Meats, doughnuts, fries, potato chips, cookies and candy bars should be avoided in a pre-exercise meal. Keep in mind that everyone is a bit different and what works for you may not work for you teammate or training partner. Factor in individual preferences and favorite foods, and an eating plan is a highly individualize thing.

Sources:

The Position Statement from the Dietitians of Canada, the American Dietetic Association, and the American College of Sports Medicine, Canadian Journal of Dietetic Practice and Research in the Winter of 2000, 61(4):176-192. Res, P., Ding, Z., Witzman, M.O., Sprague, R.C. and J. L. Ivy. The effect of carbohydrate-protein supplementation on endurance performance during exercise of varying intensity. International Journal of Sports Nutrition and Exercise Metabolism. Levenhagen DK, Carr C, Carlson MG, Maron DJ, Borel MJ, Flakoll PJ. Post exercise protein intake enhances whole-body and leg protein accretion in human. Medicine and Science in Sports & Exercise. 2002 May; 34(5): 828-37.