Monday, 3 May 2010
Athletes are always seeking ways to enhance performance and delay fatigue. Muscle glycogen is the major fuel source during prolonged, moderate to high-intensity exercise, and there is a direct relationship between depleted muscle glycogen and fatigue. Therefore, muscle glycogen repletion is vital to recovery time and maintaining top performance for athletes at all levels (1).
Glycogen repletion is important to ensure an athlete’s quick muscle recovery for subsequent practices, especially those who train, or must compete, multiple times in a single day (1). Timing, composition and the quantity of a post-exercise meal or snack is dependent upon the length and intensity of exercises, timing of the next exercise session, as well as an individual’s needs (1).
Carbohydrates For Recovery - How Much?
The current recommendation for daily carbohydrates (CHO) consumption is 5 – 7g CHO/kg/day for the general athlete and 7 – 10g/kg/day for the endurance athlete (1). Consuming CHO immediately after exercise accelerates glycogen repletion (10) because there is increased blood flow to the muscles, which results in heightened sensitivity to insulin (9). Sufficient CHO ingestion over the next 24 hours is also important. Current recommendations are to consume 1 – 1.5g of CHO/kg of body weight within 30 minutes after exercise and then again at 2-hour intervals for the next six hours (1). See Table 1 for some ideas on what to consume within 30 minutes post-exercise.
Carbohydrates For Recovery - What Type?
The type of carbohydrate (CHO) an athlete consumes after exercise can affect how much and how quickly he or she resynthesizes glycogen. Foods and/or beverages containing glucose/ sucrose, and those having a high glycemic index are preferred. Glucose and sucrose are preferred over fructose (1), as fructose promotes a lower level of glycogen resynthesis as compared to glucose (3) and larger amounts of fructose may promote gastrointestinal distress due to its slower absorption rate(3). High glycemic index foods induce higher muscle glycogen levels as compared to low glycemic index foods (1).
Readily available foods, such as whole grain cereal and skim milk, have been found to be an effective post-exercise fuel (2). In fact, one study found that the carbohydrate to protein combination found in a bowl of whole grain cereal and skim milk had a similar effect on muscle glycogen repletion as did sports drinks (2). The combination was also found to positively affect protein synthesis. From this research, it seems that whole foods can be a good alternative to commercial sports drinks, if preferred by the athlete.
Endurance athletes may benefit from consuming protein along with carbohydrates after exercise as this combination has been shown to reduce markers of muscle damage and improve post-exercise recovery. This could also have a positive effect on subsequent performances (8).
Some studies have demonstrated a benefit of Branched Chain Amino Acids (BCAA) on muscle recovery (6). BCAA’s appear to affect muscle protein metabolism during and after exercise and prevent muscle damage induced by exercise (6). The release of amino acids from muscles is decreased
when BCAA’s are ingested (6).
The goal for athletes in resistance-type exercise is to increase muscle mass and strength. The nutrition intervention for this type of activity involves stimulating net muscle protein gains during recovery. PRO ingestion increases the rate of muscle protein synthesis and inhibits protein breakdown after training (10). One study found that during prolonged resistance training, post-exercise consumption of CHO and PRO, 1 – 3 hours after resistance training stimulated improvements in strength and body composition better than a placebo (3). Essential amino acids in a dose of 40g have regularly shown to have an effect in promoting muscle protein synthesis and CHO may enhance this effect (3). The findings suggest ingesting 50 – 75g CHO with 20 – 75g PRO after heavy resistance training (3). Furthermore, adding 10g of creatine has shown to produce a significant increase in body mass as compared to just CHO and PRO (3). See Table 2 for possible CHO and PRO combinations.
Nutrition post-exercise has been proven to promote recovery for athletes. Post-exercise nutrition has been shown to increase strength and muscle
mass in athletes who participate in resistance-type exercises. Timing, composition and amount of post-exercise food is dependent upon the individual,
timing of the next exercise session and the activity performed.
Article from nsca’s performance training journal • www.nsca-lift.org • volume 9 issue 2, Debra Wein, MS, RD, LDN, CSSD, NSCA-CPT,*D and Marcia Nelson