Supplements the debate/discussion thread

The purpose of this study was to examine the effect of 30 days of β-alanine supplementation in collegiate football players on anaerobic performance measures. Subjects were randomly divided into a supplement (β-alanine group [BA], 4.5 g•d−1 of β-alanine) or placebo (placebo group [P], 4.5 g•d−1 of maltodextrin) group. Supplementation began 3 weeks before preseason football training camp and continued for an additional 9 days during camp. Performance measures included a 60-second Wingate anaerobic power test and 3 line drills (200-yd shuttle runs with a 2-minute rest between sprints) assessed on day 1 of training camp. Training logs recorded resistance training volumes, and subjects completed questionnaires on subjective feelings of soreness, fatigue, and practice intensity. No difference was seen in fatigue rate in the line drill, but a trend (P = .07) was observed for a lower fatigue rate for BA compared with P during the Wingate anaerobic power test. A significantly higher training volume was seen for BA in the bench press exercise, and a trend (P = .09) for a greater training volume was seen for all resistance exercise sessions. In addition, subjective feelings of fatigue were significantly lower for BA than P. In conclusion, despite a trend toward lower fatigue rates during 60 seconds of maximal exercise, 3 weeks of β-alanine supplementation did not result in significant improvements in fatigue rates during high-intensity anaerobic exercise. However, higher training volumes and lower subjective feelings of fatigue in BA indicated that as duration of supplementation continued, the efficacy of β-alanine supplementation in highly trained athletes became apparent.

The purpose of this study was to examine the changes in bench press strength (BPS), vertical jump (VJ), 100 yd dash time, and fat-free weight (FFW) in football players following 8 weeks of supplementation with a carbohydrate placebo (CHO), creatine monohydrate (CM), or CM plus CHO. Using a double blind random design, 24 college football players were placed into one of three treatment conditions: CHO) 35g CHO; CM) 5.25g CM plus 1g CHO; or CM+CHO) 5.25g CM and 33g CHO. All treatments were similar in taste and were ingested four times per day for five consecutive days and twice daily thereafter. All subjects weight trained for 1 h and participated in 30 min of speed drills four times per week for 8 weeks. The CM+CHO group experienced significant (p<0.05) improvement in BPS, VJ, 100 yd dash time and FFW when compared to the CHO group. However, delta scores for the CM group were not significantly different from the CHO group. These data suggest that CHO taken with CM during training may be superior to training alone for enhancing exercise performance and FFW.

Optimal nutrition and supplementation are often used to enhance performance. Thus, the purpose of this study was to examine the role kilocalorie (kcal) intake, diet composition and creatine monohydrate supplementation (CMS) had on strength/body composition of 28 NCAA division one football players during the same, intense 15-day training period. Nutritionally, athletes primarily consumed school cafeteria food (33/45 meals) though were permitted to eat ad libitum from any source. Daily diet forms, listing menu items and recommended intake based on body mass, were utilized. All food consumed was recorded by the athlete, either by marking number of servings, or by a write-in entry. Creatine monohydrate or a placebo was administered (random, double-blind design) in a “load” phase (20 grams/day, 7 days) and in a subsequent “maintenance” phase (10 grams/day, 8 days). Results indicated no significant difference between the groups for nutritional intake (kcals: p = 0.89; 5,162/5,203 kcal, mean macronutrients: p = 0.62; carbohydrate 61/58%, protein 18/19%, fat 22/23%), strength volume during the “load” phase (p = 0.98) or in a pre-post “max bench press output” during a combination “load-maintenance” phase of CMS (p = 0.19). No significant difference existed for skinfold body composition measurements (p = 0.79) but a significant increase in body mass was observed in the experimental group (p < 0.0003). {Note: A different group of teammates (n = 52; same design & cafeteria, nutrition not analyzed) revealed similar non-significant findings for strength volume (p = 0.96) but significance was found in pre-post max bench press output (p = 0.04)}. Three conclusions are warranted: (1) CMS in a typical “load” phase dose did not significantly improve strength volume compared to a placebo group. (2) Pre-post “maximal bench press output” was not significantly increased during 15 days of a “load-maintenance” phase of CMS, however trends appeared to be present. (3) Body mass with no concurrent increase in skinfold body fat thickness was significantly increased during 15 days of a “load-maintenance” phase of CMS.

A large number of studies have been published on creatine supplementation over the last decade. Many studies show that creatine supplementation in conjunction with resistance training augments gains in muscle strength and size. The underlying physiological mechanism(s) to explain this ergogenic effect remain unclear. Increases in muscle fiber hypertrophy and myosin heavy chain expression have been observed with creatine supplementation. Creatine supplementation increases acute weightlifting performance and training volume, which may allow for greater overload and adaptations to training. Creatine supplementation may also induce a cellular swelling in muscle cells, which in turn may affect carbohydrate and protein metabolism. Several studies point to the conclusion that elevated intramuscular creatine can enhance glycogen levels but an effect on protein synthesis/degradation has not been consistently detected. As expected there is a distribution of responses to creatine supplementation that can be largely explained by the degree of creatine uptake into muscle. Thus, there is wide interest in methods to maximize muscle creatine levels. A carbohydrate or carbohydrate/protein-induced insulin response appears to benefit creatine uptake. In summary, the predominance of research indicates that creatine supplementation represents a safe, effective, and legal method to enhance muscle size and strength responses to resistance training.

Current dietary protein requirements were determined using essentially sedentary individuals and, therefore, are designed for the general population. Unfortunately, the recommendations from these studies have been applied to athletes as well. Because of the vast differences in daily energy expenditure alone this would seem to be a naive approach. Moreover in recent years, considerable evidence has accumulated on athletes, primarily those involved at each end of the exercise intensity-duration continuum, i.e., strength (weight lifting) to endurance (running, cycling, or swimming), suggesting that dietary protein needs may be greater by as much as 125% in comparison to sedentary individuals. The additional protein may be necessary for use as an auxiliary fuel for endurance exercise and as a supplementary source of amino acids to build and/or maintain the large muscle mass present in those who strength train. In addition, although more speculative, it is possible that other constituents in high quality protein sources, i.e., creatine, conjugated linoleic acid, carnosine, etc. may also be beneficial. Definitive dietary recommendations for various athletic populations must await further study, but the mass of current evidence indicates that individuals involved in strength/power/speed activities may benefit from intakes of about 1.7 to 1.8 g protein • g body mass−1 • day−1 (approximately 112–125% higher than the sedentary recommendation) and those who participate in endurance activities from about 1.2–1.4 g • kg−1 • d−1 (approximately 50 to 75% higher than the sedentary recommendation). Assuming total energy intake is sufficient to cover expenditure, these intakes can be obtained from a diet consisting of about 10% energy intake as protein. Some athletes may not consume this amount of protein, especially those who consume inadequate energy (dieters or those trying to maintain an arbitrary body mass for their activity, i.e., gymnasts, dancers, wrestlers, etc.), those who are growing (children, adolescents, women who are pregnant), or those who select diets which may exclude high quality protein sources (vegetarians and seniors). Despite the common practice of consuming greater amounts of protein (2–4 g • kg−1 • d−1) among strength athletes in particular, few data exist suggesting that this has any further benefit, i.e., there appears to be a ceiling effect. Finally, the concerns expressed routinely about liver or kidney problems with high protein diets have little scientific support; however, the easy accessibility of individual amino acid supplements poses a potentially serious threat because there are likely a variety of confounding interactions and the effects of mega doses of single amino acids are largely untested. Future studies are needed to fine tune these recommendations.

To investigate the influence of carbohydrate (CHO) consumption on the acute hormonal response, and chronic adaptation to weight lifting exercise, two studies were conducted. Following a four-hour fast, seven young men (21.3 ± 3.5 y) performed (on two occasions) a nine-station weight lifting protocol, completing 3 sets of 10 repetitions at 75% of IRM (series 1). Randomly assigned, one session included the ingestion of a non-caloric placebo, and the other, a 6% CHO solution. For series 2, two groups of young men (21.3±1.5 y) participated in 12 weeks of progressive resistance weight training. Training for one group included the ingestion of a non-caloric placebo, and the other, a 6% CHO solution. In series 1, weight lifting exercise with CHO ingestion significantly (p < 0.05) elevated blood glucose and plasma insulin levels above baseline, as well as that occurring with the placebo. This resulted in a significant blunting of the cortisol response (7% with CHO compared to 99% with placebo). These findings indicate that CHO consumption during weight lifting exercise can modify the acute hormonal response to exercise. With series 2, CHO consumption continued to blunt the cortisol response to exercise during the twelve weeks of training. This is in contrast to significantly elevated cortisol levels observed for the placebo control group. Corresponding with the modified response patterns were differences in muscle growth. Weight training exercise with CHO ingestion resulted in significantly greater gains in both type I (19.1%) and type II (22.5%) muscle fibre area than weight training exercise alone. The difference in the cortisol response accounted for 74% of the variance (r= 0.8579, p= 0.006) of change in type I muscle fibre area, and 52.3% of the variance (r= 0.7231, p= 0.043) of change in type II muscle fibre area. These findings suggest that the modification of the cortisol response associated with CHO ingestion can positively impact the skeletal muscle hypertrophic adaptation to weigh training.