The effect of 4 weeks beta-alanine supplementation and isokinetic training on carnosine concentrations in type I and II human skeletal muscle fibres.

Seven male students were supplemented with beta-alanine (beta-ALG) for 4 weeks (6.4 g day(-1)) and seven with a matching placebo (PLG). Subjects undertook 4 weeks of isokinetic training with the right leg (T) whilst the left leg was untrained (UT), serving as a control. Each training session consisted of 10 x 10 maximal 90 degrees extension and flexion contractions at 180 degrees /s using a Kin-Com isokinetic dynamometer, with 1 min rest between bouts. Muscle biopsies were taken from the vastus lateralis immediately before and at the end of the supplementation period. Following freeze drying muscle fibres were dissected and characterised by their MHC profile, as type I, IIa, IIx, or as hybrids of these. Carnosine was measured by HPLC. There was a significant increase in carnosine in both T and UT legs of the beta-ALG (9.63 +/- 3.92 mmol kg(-1) dry muscle and 6.55 +/- 2.36 mmol kg(-1) dry muscle respectively). There was a significant increase in the carnosine content of all fibre phentotypes, with no significant difference between types. There were no significant differences in the changes in muscle or in fibres between the T and UT legs. In contrast there was no significant change in the carnosine content in either the T or UT legs with placebo. The results indicate that 4 weeks training has no effect on the muscle carnosine content. Whilst an increase was seen with beta-alanine supplementation, this was not further influenced by training. These findings suggest that beta-alanine availability is the main factor regulating muscle carnosine synthesis.

The effects of 10 weeks of resistance training combined with beta-alanine supplementation on whole body strength, force production, muscular endurance and body composition.

Carnosine (Carn) occurs in high concentrations in skeletal muscle is a potent physico-chemical buffer of H+ over the physiological range. Recent research has demonstrated that 6.4 g x day(-1) of beta-alanine (beta-ala) can significantly increase skeletal muscle Carn concentrations (M-[Carn]) whilst the resultant change in buffering capacity has been shown to be paralleled by significant improvements in anaerobic and aerobic measures of exercise performance. Muscle carnosine increase has also been linked to increased work done during resistance training. Prior research has suggested that strength training may also increase M-[Carn] although this is disputed by other studies. The aim of this investigation is to assess the effect of 10 weeks resistance training on M-[Carn], and, secondly, to investigate if increased M-[Carn] brought about through beta-ala supplementation had a positive effect on training responses. Twenty-six Vietnamese sports science students completed the study. The subjects completed a 10-week resistance-training program whilst consuming 6.4 g x day(-1) of beta-ala (beta-ALG) or a matched dose of a placebo (PLG). Subjects were assessed prior to and after training for whole body strength, isokinetic force production, muscular endurance, body composition. beta-Alanine supplemented subjects increased M-[Carn] by 12.81 +/- 7.97 mmol x kg(-1) dry muscle whilst there was no change in PLG subjects. There was no significant effect of beta-ala supplementation on any of the exercise parameters measured, mass or % body fat. In conclusion, 10 weeks of resistance training alone did not change M-[Carn].