Sports Fitness Training

It is well understood by the athletic community that increased carbohydrate intake (loading) can significantly enhance exercise performance in situations in which muscle glycogen stores are limiting. Less well known, but of critical importance is that there is a brief window of opportunity perhaps 60 minutes or so following exercise in which the muscle glycogen synthetic rate is significantly greater than at any other time during the day. Similarly, it is becoming clear that strength exercise causes disruptions in both muscle protein synthesis and degradation, resulting over time in substantial muscle growth. Perhaps, nutrient supplementation post­exercise might optimize muscle growth. For example, this overall growth response could be limited by energy and/or amino acid availability. If so, providing either or both could enhance muscle growth/repair via increasing protein synthesis or decreasing protein degradation. Some evidence Combining carbohydrate and amino acids may be the best approach because the insulin released in response to the carbohydrate stimulates amino acid uptake by muscle, leading, at least potentially, to enhanced protein synthetic rates . As mentioned above, some amino acids are also powerful stimulators of insulin release. Moreover, other hormones important for positive training adaptations could be involved. It appears that the essential amino acids are the most crit­ical and that only small amounts may be necessary. As further study clarifies the details of the effects of strength training on net protein balance in muscle it should become possible to prescribe precise recommendations regarding type, amounts, and timing of nutrient supplementation to maximize the anabolic stimulus following strength training. If so, this information would be of considerable benefit not only to the athletic community but also to any group of individuals who have lost muscle function due to disease or disuse (i.e., post-surgery, injuries, elderly, zero-gravity environment, etc.).