Doubling of muscle carnosine concentration does not improve laboratory 1-hr cycling time trial performance

Muscle carnosine loading through chronic oral beta-alanine supplementation has been shown to be effective for short-duration, high-intensity exercise. This randomised, placebo controlled study explored whether the ergogenic effect of beta-alanine supplementation is also present for longer duration exercise. Subjects (27 well-trained cyclists/triathletes) were supplemented with either beta-alanine or placebo (6.4 g/day) for six weeks. Time to completion and physiological variables for a 1-h cycling time-trial were compared between pre- and post-supplementation. Muscle carnosine concentration was also assessed via proton magnetic resonance spectroscopy before and after supplementation. Following beta-alanine supplementation, muscle carnosine concentration was increased by 143 ± 151% (mean ± SD; p < 0.001) in the gastrocnemius and 161 ± 56% (p < 0.001) in the soleus. Post-supplementation time trial performance was significantly slower in the placebo group (60.6 ± 4.4 to 63.0 ± 5.4 min; p < 0.01) and trended towards a slower performance following beta-alanine supplementation (59.8 ± 2.8 to 61.7 ± 3.0 min; p = 0.069). We found an increase in lactate/proton concentration ratio following beta-alanine supplementation during the time-trial (209.0 ± 44.0 (beta-alanine) vs. 161.9 ± 54.4 (placebo); p < 0.05), indicating that a similar lactate concentration was accompanied by a lower degree of systemic acidosis, even though this acidosis was quite moderate (pH ranging from 7.30-7.40). In conclusion, chronic beta-alanine supplementation in well-trained cyclists had a very pronounced effect on muscle carnosine concentration and a moderate attenuating effect on the acidosis associated with lactate accumulation, yet without affecting 1-h time-trial performance under laboratory conditions.Muscle carnosine loading through chronic oral beta-alanine supplementation has been shown to be effective for short-duration, high-intensity exercise. This randomised, placebo controlled study explored whether the ergogenic effect of beta-alanine supplementation is also present for longer duration exercise. Subjects (27 well-trained cyclists/triathletes) were supplemented with either beta-alanine or placebo (6.4 g/day) for six weeks. Time to completion and physiological variables for a 1-h cycling time-trial were compared between pre- and post-supplementation. Muscle carnosine concentration was also assessed via proton magnetic resonance spectroscopy before and after supplementation. Following beta-alanine supplementation, muscle carnosine concentration was increased by 143 ± 151% (mean ± SD; p < 0.001) in the gastrocnemius and 161 ± 56% (p < 0.001) in the soleus. Post-supplementation time trial performance was significantly slower in the placebo group (60.6 ± 4.4 to 63.0 ± 5.4 min; p < 0.01) and trended towards a slower performance following beta-alanine supplementation (59.8 ± 2.8 to 61.7 ± 3.0 min; p = 0.069). We found an increase in lactate/proton concentration ratio following beta-alanine supplementation during the time-trial (209.0 ± 44.0 (beta-alanine) vs. 161.9 ± 54.4 (placebo); p < 0.05), indicating that a similar lactate concentration was accompanied by a lower degree of systemic acidosis, even though this acidosis was quite moderate (pH ranging from 7.30-7.40). In conclusion, chronic beta-alanine supplementation in well-trained cyclists had a very pronounced effect on muscle carnosine concentration and a moderate attenuating effect on the acidosis associated with lactate accumulation, yet without affecting 1-h time-trial performance under laboratory conditions.A