Fueling Pre-, During, and Post-Exercise
In previous articles I have discussed general guidelines for how to fuel your body for exercise. Here I would like to get specific about the recommended nutrient intake prior to, during and after a workout or athletic event. Generally speaking, these guidelines are geared towards exercises lasting one hour or more. This could be a longer race (or training for that race), a soccer game, a day of basketball tournaments, or an intense gym workout or sports practice. For the purposes of this discussion, we will refer to this exercise as your “event”.
Pre-Exercise
It is important to consider your timeline surrounding your exercise session, then plan your pre-exercise meals and snacks accordingly. The goal is to keep your glycogen stores (a.k.a., muscle fuel) full and your body adequately hydrated while also avoiding any gastrointestinal distress while exercising. Therefore, pre-exercise meals and snacks are focused on carbohydrate and liquid intake.
The average person stores 500 grams of carbohydrate as glycogen in their muscle cells. There appears to be a certain threshold at which performance is impaired once muscle glycogen stores fall below a certain level; therefore, muscle glycogen stores will never truly fall to zero. The goal is to keep the muscle glycogen stores “topped off” to prevent them falling below that threshold. It is estimated that full glycogen stores will generally supply fuel for 60 - 90 minutes of exercise at 55-75% of your maximum heart rate.
Three to four hours before your event, enjoy a meal with 3-4 grams of carbohydrate per kilogram body weight. Considering you will have plenty of time to digest this food before exercising, it is appropriate to incorporate some proteins, fats and fiber into this meal. However, be mindful of your own tolerance of fibrous foods before exercise. If you have a more sensitive stomach, you may want to avoid some high fiber foods, such as broccoli, cauliflower, or bran cereals.
One to three hours before your event, enjoy a smaller meal with 1-2 grams of carbohydrate per kilogram body weight. This meal may still incorporate some proteins, fats and fiber, but in more limited amounts.
Less than one hour before your event, try a snack with 1 gram of carbohydrate per kilogram body weight. For the most part, avoid proteins, fats and fiber, as these foods will slow down your digestion, causing the food to “sit” in your stomach for too long. Consider consuming this fuel in liquid form (i.e., sports beverage) if you are concerned about a sensitive stomach.
Throughout this time, fluids should be consumed as desired. There is no need to force yourself to drink an excessive amount of fluid, as this could cause you to become overhydrated, diluting the electrolytes in your bloodstream, possibly causing a “sloshing” sensation in your stomach, and requiring you to have to go to the bathroom mid-event. Have a water bottle nearby and take drinks of water as you desire. However, be sure to drink 7 - 12 ounces of fluid 15 - 30 minutes before your event.
During Exercise
For events lasting less than one hour, there has not been a demonstrated need to consume any calories during exercise. However, if you are attempting to train your gut to tolerate food while exercising in anticipation of a future athletic event, you may be practicing having some food in your stomach during shorter bouts of exercise.
For events lasting more than one hour, aim for 30-60 grams of carbohydrate per hour for the first three hours. This fuel should not contain proteins, fats or fibers – just carbs! This could be real food, such as a banana or dried fruit, or it could be sports gels or sports drinks. Keep in mind that a sports beverage that is too concentrated in carbohydrates will often cause GI distress. Aim for a 6-8% carbohydrate solution in a sports beverage.
For events lasting more than three hours (think marathon or all-day sports tournament), aim for 60 - 90 grams of carbohydrate per hour after the first three hours. Again, focus on carbohydrates only in order to refuel glycogen stores and promote quick digestion.
Every 15 - 30 minutes, drink 6 - 12 ounces of fluid (this may be a sports drink). In general, 1 gulp equals 2 ounces of fluid. Just a 2% body weight loss in fluids during exercise has been shown to significantly impair performance and put a strain on the cardiovascular system, including increased heart rate and fatigue. Drink regularly to avoid this amount of fluid loss.
Post-Exercise
To optimize recovery, repair, and muscle protein synthesis, nourishing your body after your event is key. A good rule of thumb is to aim for a small, balanced meal or snack within 30 minutes after your exercise. Glycogen restoration and muscle protein synthesis is heightened within this 30 minute window. Your meal should contain 1.2 grams of carbohydrate and 0.4 grams of protein per kilogram body weight.
Within two hours after your event, enjoy a balanced meal with at least 1.2 grams of carbohydrate and 15 - 30 grams of protein. This meal can contain more fats and fibers.
After exercising, drink fluids to recover your sweat loss. Sweat loss is very individual, so you can calculate your sweat rate per hour by weighing yourself before and after a workout. A 1 kilogram (2.2 pound) loss is equal to about 1 liter of fluid lost. If you lose a lot of salt in your sweat, consider adding sodium to your fluids to replace the loss.
As discussed previously, it is important to listen to your hunger cues and continue to nourish yourself on recovery days. Do not restrict your intake just because you are not exercising at a high intensity that day. Oftentimes, people find themselves to be more hungry on their rest days, and that is okay!
Working with a dietitian is a great way to optimize your athletic performance with nutrition. If you would like to work with me, schedule a FREE discovery call here to see if we are a good fit!
“A great diet cannot make an average athlete elite, but a poor diet can make an elite athlete average.”