Carbohydrate is the primary fuel for most types of exercise and the most important nutrient for athletic performance. Our body runs most efficiency with a balance of protein, fat and carbohydrates, but adequate carbohydrate is a key source of energy for athletes.
- Energy that fuels muscle contractions and brain function
- Stored energy for later use. (Any glucose not needed right away gets stored in the muscles and the liver in the form of glycogen.)
- An alternative energy source to protein being used for energy
During physical exercise stored carbohydrate or glycogen is converted into energy to fuel the muscles, but this supply is not endless. The amount of carbohydrate that can be stored in the body as glycogen depends on diet and the athlete’s conditioning level. Typically total glycogen stores equal 400-700 grams (75-100g in the liver and 300-600g in the muscles). An athlete consuming a high carbohydrate diet and following a solid nutrition protocol can increase these total carbohydrate reserves up to 880g. After about 60 to 90 minutes of exercise these fuels will become depleted; therefore the need to refuel for longer training.
Health Canada's "Guide for Nutrition" Recommendations advises that 55 per cent of the total energy in our diet should come from carbohydrates. For elite athletes, it is recommended that 60% to 70% of total energy be comprised of carbohydrates. Without adequate dietary carbohydrate the body is forced to rely more on fat stores and protein from our muscles, which are less efficient energy-producing pathways. As a result, the quality of training and performance may diminish. For athletes with a busy and rigorous training schedule, both carbohydrate snacks and adequate fluid intake are essential to maintain muscle glycogen and to sustain optimal energy levels.
How much carbohydrate and fluid should we consume before, during and after exercise?
Figure skaters, for example, must have enough energy to endure long aerobic activities and have split-second power surges to jump. On top of eating adequate carbohydrates daily, taking in carbohydrate before during and after exercise is essential to provide enough fuel and promote recovery. The following table outlines the key guidelines for carbohydrate, protein and fluid intake pre-, during and post-training. It is important to note that the exact timing and type of food to consume can be very individualized. It is recommended that athletes trial various types of food to find out which works best for them.
Why eat carbohydrate?
Before: To top up energy stores and delay fatigue. What you eat depends on how much time you have, but aim for a light carbohydrate meal.
During: To help to maintain blood sugar to fuel muscles during exercise. If your training session lasts longer than 90 minutes you will need additional carbohydrates to maintain energy levels. Choose easy to digest carbohydrates and aim for 30-50 g of liquid or solid sources every 30 minutes.
After: For replenishment of your energy supply after exercise, which helps guarantee the ability to last longer in the next training session or event. For optimal recovery and replenishment of glycogen stores, eat carbohydrates and protein within 60 minutes of completing your session.
||How much?||For Example|
1-2 hours before
* easy to digest
* low fat
|Carbohydrate 2 g/kg
Protein 10-15 g
Fluids 500 ml
1 cup chocolate soy milk + 1 cup water + banana
Or, 1 Granola bar + 1 low fat yogurt + 1 cup water
|During training fuels||600-1200 ml fluid/ hour
(3-4 large gulps every 15-20 minutes)
Carbohydrate 30-60 g/hr over 60-90 minutes
|Water or sports drink 1 -2 water bottles
(~500 ml each)
* within 1 hour of session
|carbohydrate 1 g/kg
protein 15-20 g
fluids 600-1200 ml
1 tetra pack soy milk + banana + 2 cups water
Or, 1 cliff bar + apple + 2 cups water
Or, 1 Kashi granola bar + 1 cup chocolate milk + 1 cup water
More than one training session or game….
For sports where there is more than one daily training session or back-to-back events scheduled follow these additional guidelines to ensure optimal refuelling and recovery between:
|30 minutes between games||Carbohydrate||Juice or sports drink|
|1-2 hours between games||Carbohydrate||Banana
|> 2 hrs (recovery nutrition)||Carbohydrate & Protein||
1 cup chocolate milk + Nature Valley granola bar + 1 cup water
Or Cliff Bar + ¾ cup yogurt + 1-2 cups water
Or Peanut Butter & Jam sandwich + 1 cup soy milk
Or 1 Kashi Granola Bar + 1 banana + 1-2 cups water
Or 1 Apple + energy bar + 1-2 cups water
Or ¾ cup yogurt + 0.25 cup dried fruit + 1-2 cups water
What are sources of carbohydrate and fluids for exercise?
Complex carbohydrates such as whole grain pasta and cereals, legumes, fresh fruit and starchy vegetables are excellent sources because they release energy slowly, are low in fat, and are packed with nutrients and fibre. Although sports bars, gels and drinks are quick, convenient sources of energy, obtaining your energy from natural sources of food is highly recommended and more economical. For example, a medium banana and one cup of fruit yogurt supply approximately 215 calories and 40 grams of carbohydrate. A Power Bar supplies 220 kcal and 48 grams of carbohydrate. If you choose sports foods, choose those without hydrogenated or saturated fats and without additives or preservatives. There is an advantage to making your own snacks they are nutritious, unprocessed sources of carbohydrate, protein, fat, fibre, minerals, and vitamins that energize your body.
Homemade Energy Bars
- Plan ahead! Prepare your daily snack-pack the night before. Pack it full of nutritious carbohydrate-rich snacks such as a whole grain bagel with peanut butter, yogurt, fig bars, bananas, orange slices, graham crackers and granola bars.
- Develop a complete nutrition training plan. Don't just eat and keep well hydrated during competition. Practice fuelling during training so you are accustomed to it for your events. Experiment with different quantities and sources of carbohydrate (foods and fluids) during exercise to determine what keeps your body performing at optimal levels.
- Always carry a water bottle and take regular sips during activity. Ask your coach to remind you.
Note: With even a 2 percent dehydration work capacity drops by 10-20 percent.
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