l'effet placebo de la beta alanine je l'ai senti en tout cas, sur des reps difficiles ça cale, on y pense et hop une nouvelle vitesse s'enclenche et ça repart c'est l'impression que ma donnée la beta, mais bon n'est ce pas le reste qui joue et mon esprit?
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Donne de l'endurance aux vieilles personnes[Vous devez être inscrit et connecté pour voir ce lien]"J Int Soc Sports Nutr. 2008 Nov 7;5:21.
The effect of beta-alanine supplementation on neuromuscular fatigue in elderly (55-92 Years): a double-blind randomized study.
Stout JR, Graves BS, Smith AE, Hartman MJ, Cramer JT, Beck TW, Harris RC.
Department of Health and Exercise Science, University of Oklahoma, Norman, OK, USA.
[Vous devez être inscrit et connecté pour voir ce lien].
BACKGROUND: Ageing is associated with a significant reduction in skeletal muscle carnosine which has been linked with a reduction in the buffering capacity of muscle and in theory, may increase the rate of fatigue during exercise. Supplementing beta-alanine has been shown to significantly increase skeletal muscle carnosine. The purpose of this study, therefore, was to examine the effects of ninety days of beta-alanine supplementation on the physical working capacity at the fatigue threshold (PWCFT) in elderly men and women. METHODS: Using a double-blind placebo controlled design, twenty-six men (n = 9) and women (n = 17) (age +/- SD = 72.8 +/- 11.1 yrs) were randomly assigned to either beta-alanine (BA: 800 mg x 3 per day; n = 12; CarnoSyntrade mark) or Placebo (PL; n = 14) group. Before (pre) and after (post) the supplementation period, participants performed a discontinuous cycle ergometry test to determine the PWCFT. RESULTS: Significant increases in PWCFT (28.6%) from pre- to post-supplementation were found for the BA treatment group (p < 0.05), but no change was observed with PL treatment. These findings suggest that ninety days of BA supplementation may increase physical working capacity by delaying the onset of neuromuscular fatigue in elderly men and women.
CONCLUSION: We suggest that BA supplementation, by improving intracellular pH control, improves muscle endurance in the elderly. This, we believe, could have importance in the prevention of falls, and the maintenance of health and independent living in elderly men and women.PMID: 18992136 [PubMed]"
mais sur des hommes plus jeunes pas de différence constatée sur la base de test choisie:[Vous devez être inscrit et connecté pour voir ce lien]"Eur J Appl Physiol. 2009 Feb;105(3):357-63. Epub 2008 Nov 7.
The effects of beta-alanine supplementation and high-intensity interval training on neuromuscular fatigue and muscle function.
Smith AE, Moon JR, Kendall KL, Graef JL, Lockwood CM, Walter AA, Beck TW, Cramer JT, Stout JR.
Department of Health and Exercise Science, Metabolic and Body Composition Laboratory, University of Oklahoma, Norman, OK 73019, USA.
The purpose of this study was to determine the effects of beta-alanine supplementation and high-intensity interval training (HIIT) on electromyographic fatigue threshold (EMG(FT)) and efficiency of electrical activity (EEA). A total of 46 men completed four, 2-min work bouts on a cycle ergometer. Using bipolar surface electrodes, the EMG amplitude was averaged and plotted over the 2-min. The resulting slopes were used to calculate EMG(FT) and EEA. Following initial testing, all participants were randomly assigned to either placebo (PL; n = 18), beta-alanine (BA; n = 18) or control groups (CON; n = 10). Following randomization, participants engaged in 6 weeks of HIIT training. Significant improvements in EMG(FT) and EEA resulted for both training groups. In conclusion, HIIT appeared to be the primary stimulus effecting EMG(FT) or EEA,
suggesting adaptations from HIIT may be more influential than increasing skeletal muscle carnosine levels on delaying fatigue in recreationally active men.PMID: 18989693 [PubMed - indexed for MEDLINE]"
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[Vous devez être inscrit et connecté pour voir ce lien]J Strength Cond Res. 2006 Nov;20(4):928-31.
Effects of twenty-eight days of beta-alanine and creatine monohydrate supplementation on the physical working capacity at neuromuscular fatigue threshold.
Stout JR, Cramer JT, Mielke M, O'Kroy J, Torok DJ, Zoeller RF.
Department of Health and Exercise Science, University of Oklahoma, Norman, OK 73019, USA.
[Vous devez être inscrit et connecté pour voir ce lien]The purpose of this study was to examine the effects of 28 days of beta-alanine (b-Ala) and creatine monohydrate (CrM) supplementation on the onset of neuromuscular fatigue by using the physical working capacity at neuromuscular fatigue threshold (PWC(FT)) test in untrained men. Fifty-one men (mean age +/- SD = 24.5 +/- 5.3 years) volunteered to participate in this 28-day, double-blind, placebo-controlled study and were randomly assigned to 1 of 4 groups: placebo (PLA; 34 g dextrose; n = 13), CrM (5.25 g CrM plus 34 g dextrose; n = 12), b-Ala (1.6 g b-Ala plus 34 g of dextrose; n = 12), or b-Ala plus CrM (CrBA; 5.25 g CrM plus 1.6 g b-Ala plus 34 g dextrose; n = 14). The supplement was ingested 4 times per day for 6 consecutive days, then twice per day for 22 days before posttesting. Before and after the supplementation, subjects performed a continuous incremental cycle ergometry test while a surface electromyographic signal was recorded from the vastus lateralis muscle to determine PWC(FT). The adjusted mean posttest PWC(FT) values (covaried for pretest PWC(FT) values) for the b-Ala and CrBA groups were greater than those for the PLA group (p < or = 0.05). However, there were no differences between the CrM vs. PLA, CrBA vs. b-Ala, CrM vs. b-Ala, or CrM vs. CrBA groups (p > 0.05).
These findings suggested that b-Ala supplementation may delay the onset of neuromuscular fatigue. Furthermore, there appeared to be no additive or unique effects of CrM vs. b-Ala alone on PWC(FT).
PMID: 17194255 [PubMed - indexed for MEDLINE]
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[Vous devez être inscrit et connecté pour voir ce lien]"J Appl Physiol. 2007 Nov;103(5):1736-43. Epub 2007 Aug 9.
beta-Alanine supplementation augments muscle carnosine content and attenuates fatigue during repeated isokinetic contraction bouts in trained sprinters.Derave W, Ozdemir MS, Harris RC, Pottier A, Reyngoudt H, Koppo K, Wise JA, Achten E.
Dept. of Movement and Sport Sciences, Ghent Univ., Watersportlaan 2, B-9000 Ghent, Belgium.
[Vous devez être inscrit et connecté pour voir ce lien]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.
PMID: 17690198 [PubMed - indexed for MEDLINE]"
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une dernière pour les dames:
[Vous devez être inscrit et connecté pour voir ce lien]"Amino Acids. 2007;32(3):381-6. Epub 2006 Nov 30.
Effects of beta-alanine supplementation on the onset of neuromuscular fatigue and ventilatory threshold in women.
Stout JR, Cramer JT, Zoeller RF, Torok D, Costa P, Hoffman JR, Harris RC, O'Kroy J.
Department of Health and Exercise Science, University of Oklahoma, Norman, OK 73019-6081, USA.
[Vous devez être inscrit et connecté pour voir ce lien]This study examined the effects of 28 days of beta-alanine supplementation on the physical working capacity at fatigue threshold (PWCFT), ventilatory threshold (VT), maximal oxygen consumption (VO2-MAX), and time-to-exhaustion (TTE) in women. Twenty-two women (age+/-SD 27.4+/-6.1 yrs) participated and were randomly assigned to either the beta-alanine (CarnoSyn) or Placebo (PL) group. Before (pre) and after (post) the supplementation period, participants performed a continuous, incremental cycle ergometry test to exhaustion to determine the PWCFT, VT, VO2-MAX, and TTE. There was a 13.9, 12.6 and 2.5% increase (p<0.05) in VT, PWCFT, and TTE, respectively, for the beta-alanine group, with no changes in the PL (p>0.05). There were no changes for VO2-MAX (p>0.05) in either group. Results of this study indicate that beta-alanine supplementation delays the onset of neuromuscular fatigue (PWCFT) and the ventilatory threshold (VT) at submaximal workloads, and increase in TTE during maximal cycle ergometry performance. However, beta-alanine supplementation did not affect maximal aerobic power (VO2-MAX).
In conclusion, beta-alanine supplementation appears to improve submaximal cycle ergometry performance and TTE in young women, perhaps as a result of an increased buffering capacity due to elevated muscle carnosine concentrations.
PMID: 17136505 [PubMed - indexed for MEDLINE]"
Sujet: Booster d'entrainement 
Mer 25 Nov 2009 - 21:08
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