β-Alanine supplementation augments muscle carnosine content and attenuates fatigue during repeated isokinetic contraction bouts in trained sprinters

Abstract

Carnosine (beta-alanyl-l-histidine) is present in high concentrations in human skeletal muscle. The ingestion of beta-alanine, the rate-limiting precursor of carnosine, has been shown to elevate the muscle carnosine content. We aimed to investigate, using proton magnetic resonance spectroscopy (proton MRS), whether oral supplementation with beta-alanine during 4 wk would elevate the calf muscle carnosine content and affect exercise performance in 400-m sprint-trained competitive athletes. Fifteen male athletes participated in a placebo-controlled, double-blind study and were supplemented orally for 4 wk with either 4.8 g/day beta-alanine or placebo. Muscle carnosine concentration was quantified in soleus and gastrocnemius by proton MRS. Performance was evaluated by isokinetic testing during five bouts of 30 maximal voluntary knee extensions, by endurance during isometric contraction at 45% maximal voluntary contraction, and by the indoor 400-m running time. beta-Alanine supplementation significantly increased the carnosine content in both the soleus (+47%) and gastrocnemius (+37%). In placebo, carnosine remained stable in soleus, while a small and significant increase of +16% occurred in gastrocnemius. Dynamic knee extension torque during the fourth and fifth bout was significantly improved with beta-alanine but not with placebo. Isometric endurance and 400-m race time were not affected by treatment. In conclusion, 1) proton MRS can be used to noninvasively quantify human muscle carnosine content; 2) muscle carnosine is increased by oral beta-alanine supplementation in sprint-trained athletes; 3) carnosine loading slightly but significantly attenuated fatigue in repeated bouts of exhaustive dynamic contractions; and 4) the increase in muscle carnosine did not improve isometric endurance or 400-m race time.

Effect of β-alanine supplementation on 20 km cycling time trial performance

“…As such, we cannot con rm in the present study that muscle carnosine contents were signi cantly increased and, if so, what the magnitude of this increase was. However, supplementation with β-alanine at this level has consistently been shown to increase muscle carnosine concentrations by over 60% 8,11 , with others reporting no non-responders to β-alanine supplementation 11,21,31 . Indeed, only one participant from the series of muscle studies to-date has failed to respond to β-alanine supplementation with an increase in muscle carnosine 8 .…”

Muscle Carnosine Metabolism and β-Alanine Supplementation in Relation to Exercise and Training

“…Data are compiled from subjects of previous studies from our laboratory. Carnosine concentration is measured by means of proton MRS, as previously described [1], and expressed relative to the water signal. …”

Untitled

“…Since increased carnosine storage results in reduced muscle pain and fatigue after physical exercise [36][37][38][39], many athletes are using beta-alanine as a food supplement. The therapeutic effects of increased carnosine storage have been barely explored in diseases such as diabetes, which are characterized by oxidative injury.…”

“…Enzyme measurements for CNDP1 in human sera of healthy adults and diabetic patients have provided indications for post-translational modifications of CNDP1, which influence its prolonged enzyme activity by additional glycosylation [46]. In diabetic patients with microvascular complications, non-invasive measurement of tissue carnosine concentrations by proton magnetic resonance spectroscopy (1H-MRS) shows a significant reduction of carnosine concentrations in skeletal muscles of patients with type 2 diabetes, but not in patients with type 1 diabetes [36]. Oral administration of β-alanine, the rate limiting amino acid for the biosynthesis of carnosine [48], to healthy volunteers during 4 weeks resulted in reduced fatigue after physical exercise and in 30-50% increase of carnosine storage in peripheral muscle tissue, as determined again by proton-MRS [52].…”