The effects of amino acid supplementation on hormonal responses to resistance training overreaching

The purpose of this investigation was to examine the effects of amino acid supplementation on muscular performance and resting hormone concentrations during resistance training overreaching. Seventeen resistance-trained men were randomly assigned to either an amino acid (AA) or a placebo (P) group and underwent 4 weeks of total-body resistance training designed to induce a state of overreaching. The protocol consisted of two 2-week phases (phase 1, 3 sets of 8 exercises performed for 8-12 repetitions; phase 2, 5 sets of 5 exercises performed for 3-5 repetitions). Muscle strength and resting blood samples were determined before (T1) and at the end of each training week (T2-T5). One-repetition maximum squat and bench press decreased at T2 in the P group but not in the AA group; both groups showed similar increases in strength at T3 to T5. Significant elevations in serum creatine kinase and uric acid were observed at T2 in the P group; the elevation in creatine kinase correlated highly to reductions in 1-repetition maximum squat (r = -0.67, r(2) = 0.45). Significant elevations in serum sex hormone-binding globulin were observed during overreaching in the P group from T2 to T5; this response was abolished in the AA group. Significant reductions in total testosterone were observed in the P group at T4 compared with T1, and total testosterone values were higher for the AA group than for the P group from T2 to T4. Serum 22-kd growth hormone concentrations were elevated at T2 to T5 in P group only. No differences were observed in resting cortisol and insulinlike growth factor 1. Hemoglobin concentrations were significantly reduced at T2 to T5 in the P group. These results indicate that the initial impact of high-volume resistance training is muscle strength reduction and hormonal/biochemical alterations. It appears that amino acid supplementation is effective for attenuating muscle strength loss during initial high-volume stress, possibly by reducing muscle damage by maintaining an anabolic environment

Effect of training load on simulated team sport match performance

This study examined the effect of training load on running performance and plasma markers of anaerobic metabolism, muscle damage, and inflammation during a simulated team sport match performance. Seven team sport athletes (maximal oxygen uptake, 47.6 ± 4.2 mL·kg–1·min–1) completed a 60-min simulated team sport match before and after either 4 days of HIGH or LOW training loads. Venous blood samples were taken pre-match, immediately post-match, and 2 h post-match for interlukin-6, monocyte chemoattractant protein-1 (MCP-1), creatine kinase (CK), lactate dehydrogenase, C-reactive protein, xanthine oxidase (XO), and hypoxanthine. Following HIGH training load, sprint velocity decreased (p < 0.001) and total distance covered was reduced (HIGH 5495 ± 670 m, LOW 5608 ± 674 m, p = 0.02) was observed during the simulated match protocol compared with the LOW match simulation. Decreased performance capacity was accompanied by a significant increase in serum CK concentration (HIGH 290 ± 62 U·L–1, LOW 199 ± 33 U·L–1, p = 0.005). The HIGH training also resulted in a decreased post-match hypoxanthine and MCP-1 and an increase in XO concentration 2 h post-match. Four days of increased training load reduced running performance during the match simulation and altered the metabolic and inflammatory response to high-intensity intermittent exercise.Katie May Slattery, Lee Kenneth Wallace, David John Bentley, Aaron James Coutt

Low carbohydrate diets and performance

Athletes are continually searching for means to optimize their performance. Within the past 20 years, athletes and scientists have reported and/or observed that consuming a carbohydrate restricted diet may improve performance. The original theories explaining the purported benefits centered on the fact that fat oxidation increases, thereby "sparing" muscle glycogen. More recent concepts that explain the plausibility of the ergogenicity of low carbohydrate, or high fat, diets on exercise performance pertain to an effect similar to altitude training. We and others have observed that, while fat oxidation may be increased, the ability to maintain high intensity exercise (e.g., above the lactate threshold) seems to be compromised or at least indifferent compared to when more carbohydrate was consumed. That said, clinical studies clearly demonstrate that ad-libitum low carbohydrate diets elicit greater decreases in body weight and fat than energy equivalent low fat diets, especially over a short duration. Thus, while low carbohydrate and high fat diets appear detrimental or indifferent relative to performance, they may be a faster means to achieve a more competitive body composition