Optimal Nutrition for Exercise and Sports
Eating - before, during and after exercise
Optimal nutrition for sports and exercise has three major objectives.
- Optimal performance - expressed as speed, strength, power and endurance.
- Optimal recovery - so you can do it again very soon.
- Optimal health - so you can repeat it forever - well at least for a long long time.
What to eat before, during and after exercise has provided the platform for many "round table" discussions - in the parlor, the classroom, the locker room and your favorite watering hole.
Students of ancient history will recall accounts of dietary manipulation for optimal performance going back to the Gladiators. They apparently ate ground lion's teeth and raw meat prior to performances in hopes of acquiring the ferocious characteristics of the lion.
Science and experience have produced many trends and attitude changes over the years and this is a summary of where that has lead.
Develop a WOE (way of eating) that will optimize your health. This should include the storage and replacement of adequate energy in muscles so you are always ready for action.
I adhere to "The Better Balanced Diet", the 40-30-30 approach. That means 40 percent of calories from carbohydrates, preferably with a low glycemic index. 30 percent of calories from good quality, easily digestible protein and 30 percent of calories from good quality fats. The fats should include approximately equal portions of essential fatty acids, mono unsaturated fats and saturated fats.
My strongest warning is "do not go below 30 per cent of calories from fat", except in the meals 24 hours prior to an endurance event. You make good use of fat during exercise and it has other redeeming qualities (the subject of a future column).
This WOE should ensure adequate muscle glycogen stores for most exercise tasks which last for up to one hour and still provide the nutrients for optimizing the immune system and maintaining adequate blood glucose levels to feed the brain.
In anticipation of high intensity and long duration activities, it is wise to top up glycogen stores and blood sugar with a pre-event meal higher in carbohydrates (approximately 60 percent of calories) but do not ignore the protein.
A recent article in the American Journal of Nutrition recommends the protein content of a pre-event meal remain at 20 percent or higher. It has now been well established that endurance athletes demand more protein than weight lifters. After all they challenge their systems at 75 percent ++ of aerobic capacity for considerably longer times than non-endurance athletes.
It is always wise to ensure adequate hydration prior to commencing activity. In intermittent activities like team sports, individual skill sports and sprint events, water is usually the beverage of choice.
Marathons, triathlons and other ultra endurance challenges may warrant the use of a good quality (one with 6 to 8 electrolytes and primarily a glucose polymer carbohydrate source) sport drink of 8 to 16 ounces in the half hour prior to performance.
Most events lasting less than one hour demand the replacement of lost fluid every 10 to 15 minutes, if optimum performance is the objective. Even small increments of dehydration have shown significant decreases in performance.
Short duration events without water will not hurt your health but may not give you optimal performance. Water is usually adequate.
Longer duration events and/or within a very hot environment, electrolyte and carbohydrate replacement will be warranted. The objective of a carbohydrate drink during the performance is to maintain blood glucose levels, to spare the stored protein and glycogen, by providing easy accessible energy for the brain and some of the working muscles.
The brain uses glucose for energy so you never want to become hypoglycemic during a performance. If you choose to use one of the "Gel" products you must drink lots of extra water or you will find them counter productive.
Remember, there is no evidence that an overload of carbohydrates in muscles or blood will help performance in sub one hour activities. Muscle glycogen depletion only becomes a limiting factor when the intensity is high (over 75 percent of aerobic capacity) and the duration is long (over one hour).
Similarly, blood sugar cannot exceed certain levels. If blood sugar is chronically high it will induce an insulin response which is reflected by fatigue during exercise.
A long time friend, who holds several weight lifting records, once said to me "The 3 most important elements of training for optimal results are recovery, recovery and recovery".
That is when all of the "good things" happen to your physiology. It is probably the most ignored part of athletes' diet and yet it may be the most important part.
Naturally you want to re-hydrate immediately after heavy exercise. This will help to carry the electrolytes to their proper places, help to cool the system and help to carry accumulated toxins out of the body. Plan on drinking 2 cups for every pound of sweat lost.
The second objective of recovery is replacing muscle and liver glycogen stores and the replacement of the "branched chain amino acids" (BCAA), the protein portion which is metabolized during exercise.
If you don't replace glycogen, recovery of energy is slow and your willingness to do it again soon, is one of reluctance. Plan on consuming 50 to 100 grams of carbohydrates within the first 15 minutes of recovery. Go for liquids first. Following a marathon type of activity, plan to eat approximately 600 grams of carbohydrates within the first 24 hours following the event.
If you don't replace the BCAA's, you find your muscles talking strange languages (stiffness and soreness) to you approximately 1 to 2 days after the intense workout. To encourage the glycogen replacement, consume adequate and in this case, high glycemic index carbohydrates in the 2 hours immediately following exercise.
This is the one window of opportunity when you want insulin to rise quickly and induce storage of glycogen. The elevated insulin will also help to carry the BCAA's (assuming you consumed some) into the muscle. So it is also wise to include some protein in your recovery plan.
Dr. John Ivy published a study in 1992 in the Journal of Applied Physiology which demonstrated optimum glycogen and BCAA recovery occurred when a recovery drink of carbohydrate (glucose polymer) and protein (whey protein isolate) in the ratio of 3:1 in favor of the carbohydrate was consumed.
Others have reproduced these results in recent years and it has lead to the development of some excellent recovery drink products. You could also use cereal in milk or protein powders in juice.
The third recovery strategy should be one of optimal nutrition. That means nutrition high in vitamins and minerals.
During exercise, we naturally produce free radicals which are molecules that become toxic when exposed to oxygen. These oxidized free radicals are apparently responsible for many ailments ranging from flu and colds, to cancer and heart disease.
It has been shown that 40 per cent of Marathon finishers are ill within one week of finishing their run. That is a sign of a depressed or challenged immune system.
The only thing that helps to build and maintain a healthy immune system is adequate nutrition. So eat lots of colorful vegetables, protein, essential fatty acids and take your supplements to stay happy in your exercise.
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