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

University of Chichester, Chichester, England, United Kingdom
Journal of Applied Physiology (Impact Factor: 3.06). 12/2007; 103(5):1736-43. DOI: 10.1152/japplphysiol.00397.2007
Source: PubMed

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.

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    • "The ergogenic effect of β-alanine is not always observed when athletes are tested under conditions that closely simulate competitive performance, for example, swimming (50–400 m competition swim times) (Chung et al., 2012), 1-h cycling time trial (TT) performance (Chung, Baguet, Bex, Bishop, & Derave, 2014) and 400-m running TT performance (Derave et al., 2007). A recent meta-analysis by Hobson, Saunders, Ball, Harris, and Sale (2012) suggests that β-alanine supplementation could significantly increase time to exhaustion (TTE) during supramaximal exercise but not decrease exercise time (i.e. "
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    ABSTRACT: The varying results reported in response to β-alanine supplementation may be related to the duration and nature of the exercise protocol employed. We investigated the effects of β-alanine supplementation on a wide range of cycling performance tests in order to produce a clear concise set of criteria for its efficacy. Fourteen trained cyclists (Age = 24.8 ± 6.7 years; VO2max = 65.4 ± 10.2 mL·kg·min−1) participated in this placebo-controlled, double-blind study. Prior to supplementation, subjects completed two (familiarization and baseline) supramaximal cycling bouts until exhaustion (120% pre-supplementation VO2max) and two 1-, 4- and 10-km cycling time trial (TT). Subjects then supplemented orally for 4 weeks with 6.4 g/d placebo or β-alanine and repeated the battery of performance tests. Blood lactate was measured pre-exercise, post-exercise and 5 min post-exercise. β-alanine supplementation elicited significant increases in time to exhaustion (TTE) (17.6 ± 11.5 s; p = 0.013, effect compared with placebo) and was likely to be beneficial to 4-km TT performance time (−7.8 ± 8.1 s; 94% likelihood), despite not being statistically different (p = 0.060). Performance times in the 1- and 10-km TT were not affected by treatment. For the highly trained cyclists in the current study, β-alanine supplementation significantly extended supramaximal cycling TTE and may have provided a worthwhile improvement to 4-km TT performance. However, 1- and 10-km cycling TT performance appears to be unaffected by β-alanine supplementation.
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    • "Residual water and lipid peaks were removed by an HSVLD algorithm from the carnosine spectra. As a result of the more stable behavior (less orientation-dependent features), longer T 2 relaxation and higher signal-to-noise ratio (SNR) (3,9,19,22), only the C2-H peaks of carnosine and water were analyzed further. They were fitted in AMARES using single Lorentzian line shapes without constraints. "
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    ABSTRACT: The aims of this study were to observe the behavior of carnosine peaks in human soleus (SOL) and gastrocnemius (GM) muscles following acute exercise, to determine the relaxation times and to assess the repeatability of carnosine quantification by (1) H MRS at 7 T. Relaxation constants in GM and SOL were measured by a stimulated echo acquisition mode (STEAM) localization sequence. For T1 measurement, an inversion recovery sequence was used. The repeatability of the measurement and the absolute quantification of carnosine were determined in both muscles in five healthy volunteers. For absolute quantification, an internal water reference signal was used. The effect of acute exercise on carnosine levels and resonance lines was tested in eight recreational runners/cyclists. The defined carnosine measurement protocol was applied three times - before and twice after (approximately 20 and 40 min) a 1-h submaximal street run and additional toe-hopping. The measured T1 relaxation times for the C2-H carnosine peak at 7 T were 2002 ± 94 and 1997 ± 259 ms for GM and SOL, respectively, and the T2 times were 95.8 ± 9.4 and 81.0 ± 21.8 ms for GM and SOL, respectively. The coefficient of variation of the carnosine quantification measurement was 9.1% for GM and 6.3% for SOL, showing high repeatability, and the intraclass correlation coefficients (ICCs) of 0.93 for GM and 0.98 for SOL indicate the high reliability of the measurement. Acute exercise did not change the concentration of carnosine in the muscle, but affected the shape of the resonance lines, in terms of the shifting and splitting into doublets. Carnosine measurement by (1) H MRS at 7 T in skeletal muscle exhibits high repeatability and reliability. The observed effects of acute exercise were more prominent in GM, probably as a result of the larger portion of glycolytic fibers in this muscle and the more pronounced exercise-induced change in pH. Our results support the application of the MRS-based assessment of carnosine for pH measurement in muscle compartments. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.
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    • "popularity as an ergogenic aid is beta-alanine (BA), which is suggested to be effective for increasing high-intensity exercise performance (Derave et al. 2007; Hill et al. 2007). BA is a non-essential amino acid physiologically functioning as the precursor to carnosine (Culbertson et al. 2010; Smith et al. 2009), which increases the buffering capacity of H + (Derave et al. 2010; Eudy et al. 2013; Sale et al. 2010). "
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