Sports Nutrition

Diet and Exercise

Whether you’re an exercise enthusiast or an elite athlete, it helps to understand how nutrients are used to power your body. Carbohydrates, fats and protein are energy-yielding macronutrients while water, vitamins and minerals are non-energy yielding micronutrients.  All carbohydrates are broken down to make glucose which is the body’s primary source of energy.  Proteins and fats also provide energy but through a more circuitous route. 

Whether you are planning a trip to the gym or are getting ready for the big game or race then it may be prudent to carefully plan your pre-workout meal.  Such meals should be high in carbohydrate content but low in fat and fiber.  If your stomach is full of fat and fiber during exercise your body will use more resources on digestion than to power your workout.   Of course, fiber at any other time ensures good health.

A suitable pre-game meal might consist of whole wheat toast with sliced banana and cinnamon or a fruit smoothie made with non-dairy milk. The following table is a recommendation for daily macronutrient levels.

Macronutrient	% Total Daily Calories
Carbohydrates	45-65
Fats	20-35
Proteins	10-30

 

The glucose derived from carbohydrates that is not used immediately for energy is stored in the liver in the form of glycogen.  However, this storage form has a limited capacity of approximately 2,000 calories.  Any glucose above this amount is converted to fat. 

Some athletes who follow a Ketogenic diet actually rely on fatty acids for energy.   In this regimen, fats comprise 75% of total calorie consumption.  Although this type of diet promotes fat burning and muscle development it should only be followed under the guidance of a healthcare practitioner.   

Dietary protein is critical for muscle development.  Consumption within two hours following a vigorous workout will facilitate muscle repair.  Proteins are comprised of amino acids, nine of which are “essential” meaning that your body MUST get them from your diet.  Animal proteins are Complete meaning that they contain all of the essential amino acids.  Vegans and vegetarians must reply on Soy, since this is the only plant protein known to contain all of the essential amino acids.  Some athletes will take amino acid supplements to ensure adequacy but this can lead to an imbalance of amino acid levels.  When amino acids are over supplied the body cannot store them so it will either convert them to glucose for storage as glycogen or it will convert them to fat.  Since the body can also use amino acids for fuel it may burn the amino acids instead of fat.

Do athletes really need to take supplements?  A well-nourished athlete consumes all of the vitamins and minerals they need from whole food.  However, there is no down side to taking a Multi-vitamin with or without iron, depending on the individual needs. Creatine is an amino-acid-like supplement thought to be helpful in muscle development.  In actuality, your muscles make all the creatine they need.  A protein powder may be useful as a meal replacement, so long as it is complete (eg. Whey or Soy-based).  Powders with added nutrients from additional plant sources (pea, rice, green vegetables, etc) make an especially healthy choice.