An important area in the realm of sports nutrition is the timing of food and fluid consumption around exercise. In general, nutrition guidelines for athletes for each of the macronutrients are as follows: 6-10 grams carbohydrate per kilogram body weight per day, 1.2- 1.7 grams protein per kilogram body weight per day, and 20%-30% of total daily energy from fat (Rodriguez et. al 2009). The specific recommendations for each time frame surrounding exercise are detailed below.
Eating before exercise has been shown to improve exercise performance when compared to exercising in a fasted state (Maffucci and McMurray 2000, Jentjens et al. 2003, Mosely et al. 2003). In regard to the composition of the pre-exercise meal or snack, it is recommended that it be high in carbohydrates, low in fat, moderate in protein, low in fiber, provide adequate fluid, and be familiar to the athlete (Rodriguez et. al 2009).
In general, larger meals can be consumed when there is a greater time gap between eating and exercise, whereas smaller amounts should be consumed if eating and exercise are in close proximity. In terms of carbohydrate, it is recommended that 1-4 grams carbohydrate per kilogram body weight be consumed 1-4 hours prior to exercise (Sugiura and Kobayashi 1998). For fluid needs, at least four hours prior to exercise it is recommended that water or a sports drink be consumed in the amount of approximately 5-7 milliliters per kilogram body weight (Rodriguez et. al 2009).
Fueling during exercise is of greatest importance during prolonged exercise. For exercise bouts lasting less than 45-60 minutes, water is generally sufficient. However, endurance performance has been shown to be benefited with drinking sports beverages that contain 6-8% carbohydrate during exercise (Coggan and Coyle 1991, Nicholas et al. 1995, Jeukendrup et al. 1997). For events lasting longer than one hour it is recommended that carbohydrate intake be in the range of 30-60 grams carbohydrate per hour, or 0.7 grams carbohydrate per kilogram body weight per hour (McConell et al. 1996, Currell and Jeukendrup 2008). Carbohydrates may be obtained from food, gels, or sports beverages, the latter option also providing needed fluid.
In regard to fluid intake during exercise, specific general recommendations for fluid replacement during exercise have not been established, as these general guides would likely be inappropriate for many situations (Sawka et al. 2007). Thus, fluid intake should be determined for each athlete individually based on the length of exercise, sweat rate, and opportunities to drink (Rodriguez et. al 2009).
The period immediately following exercise is a time when the body is best positioned to restore glycogen (the storage form of carbohydrates in the body) at the highest rate (Sugiura and Kobayashi 1998). It is recommended that carbohydrates be consumed within 30 minutes after exercise and that 1.5 grams carbohydrate per kilogram be consumed in the first hour following exercise (Ivy et al. 1988, Sugiura and Kobayashi 1998). Adding protein as part of a meal after exercise may be beneficial in regard to muscle protein synthesis and repair (Rodriguez et al. 2007, van Loon et al. 2013). In regard to specific amounts or time frames for protein ingestion surrounding exercise, additional research is needed (van Loon et al. 2013).
If recovery time is not limited, normal meals, snacks, and water intake should be sufficient to replenish fluids lost. In situations where recovery time is limited, or there is excess dehydration, 1.5 liters of fluid for each kilogram of body weight lost should be consumed (Sawka et al. 2007).
When attempting to meet nutrition needs, the timing of eating surrounding exercise is an important consideration. Appropriate meal timing and composition before, during, and after exercise can assist in improving athletic performance.
By: Jamie Saunders, University of Utah
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Articles by Jamie Saunders.