VO₂Connection

There are several fueling strategies that can be used to train and recover from training most effectively. Proper nutrition is necessary to feel optimal while training and to prepare for the next session. Before training it is important to be well-hydrated and not glycogen depleted. Dehydration or glycogen depletion can reduce the quality of a training session and overall enjoyment.

Dehydration and overhydration not only reduces performance but can be dangerous. When exercising aerobically on hot and humid days the body may require upwards of 1-2 liters of fluids per hour but it is also important not to overhydrate. Hyponatremia is a dangerous condition that can cause cardiac failure due to very low serum sodium levels (from overhydration or excessive sodium losses). To avoid hyponatermia consume fluids with electrolytes (sodium and potassium). Pre and post exercise weigh-ins are useful to determine fluid losses. It is important to adjust fluid consumption so that no weight is gained throughout the workout and minimal weight is lost. As a general rule of thumb in warm conditions, drink 0.5 liters of fluid 1 hour prior to exercise, 1 liter per hour of exercise, and after exercise consume as much fluid as needed until body weight is returned to normal.

Common signs of glycogen depletion are lethargy, decreased power output, and a general feeling of malaise and fatigue. For maximal glycogen repletion, athletes that perform more than 90 minutes of continual intense aerobic exercise daily should consume 8-10 g per kg body weight of carbohydrate daily. For a 150 pound athlete this is about 675 g or 2700 kcal from carbohydrate alone! Timing of consumption is everything. After training it is very important to replenish muscle glycogen as soon as possible. Muscle tissue extracts glucose from circulation at a maximal rate up to thirty minutes after exercise. This is very important for people training daily or twice a day. Miss this thirty minute window and risk becoming glycogen depleted. To most effectively replenish muscle glycogen focus on simple carbohydrates that are broken down and enter the blood stream quickly (foods high on the glycemic index). Examples of these types of carbohydrates are: fresh and dried fruit, most sport drinks, juices, energy gels, and even sugary candies and refined breads. Recent studies have indicated that consuming a few grams of protein post-exercise in addition to simple carbohydrates further facilitates the muscles ability to absorb glucose.

Foods low on the glycemic index (GI) may minimize insulin secretions and increase fatty acids in the blood, thereby sparing glycogen. Foods higher in fat, protein, and fiber tend to effect insulin levels to a lesser extent and are lower GI foods. These foods should be consumed before workouts to maintain normal blood glucose and insulin levels throughout the training session. Whole grains, peanut butter, protein sources, and most vegetables and dairy products are low GI foods.

Some usable applications to the above suggestions include the following: When training in the morning, one should first have a light snack and at least 12 ounces of fluid. A good pre-workout morning meal could consist of a piece of whole wheat toast with one tablespoon of peanut butter, a half cup of milk, and 8 ounces of water 30 minutes prior to exercise. This is enough fuel to get through the workout without causing stomach upset or arriving home famished. Why eat before a morning workout if not hungry? Recent studies have shown that muscle is built more efficiently throughout and after the workout if a combination of protein and carbohydrate is consumed prior. Lunch and snacks should be appropriately planned for mid-day and evening workouts. Train to soon after a meal and risk feeling lethargic or GI distress; train to late and risk “bonking” or cutting the workout short due to hunger pangs or low blood glucose. Eat a lunch that is well-balanced in macronutrients and wait two to three hours to exercise. A light snack may be necessary if exercising more than three or four hours after the last meal is consumed. Various energy bars are great quick fixes, convenient, have a desirable macronutrient ratio, and require very little planning. Yogurt, half a sandwich, granola bars, fruit and cheese are also good options. After training hydrate with a beverage that contains some form of sugar and a little sodium and consume about 200-400kcals of high GI carbohydrate within thirty minutes of exercise.

Personal preference also plays a major role in what should be consumed before or after a workout. Some athletes may not be able to tolerate much food prior to working out or may have very little appetite after a training session or race. It is important to acknowledge these issues. Liquid calories are often the best option for athletes with appetite and GI issues.

More than getting caught-up on what is high GI, low GI, grams of carbohydrate, and liters of water the point of this article is to inform the reader that they should be aware of nutrition and hydration before and after exercise. It not only affects performance but also quality of training on a daily basis.

Abigail Larson MS, CSCS