High-Intensity Interval Training Augments Muscle Carnosine in the Absence of Dietary Beta-alanine Intake

Abstract

In the absence of any dietary intake of β-alanine, HIIT increased MCarn content. The contribution of increased MCarn to the total increase in βmin vitro appears to be small.

Magnetic Resonance Spectroscopy as a Non-invasive Method to Quantify Muscle Carnosine in Humans: a Comprehensive Validity Assessment

“…On the other hand, carnosine peaks in the HPLC chromatogram are large, sharp and easily quantifiable across the entire physiological range. Previous studies in the literature also appear to support the discrepancy between 1H-MRS and HPLC measurements of muscle carnosine, since HPLC studies consistently show 40-80% increases in muscle carnosine in response to 4 weeks of a 6.4 g.day −1 dosage of β-alanine supplementation 8,9,19 , whereas studies using 1H-MRS show much larger increases of 140-160% in muscle carnosine 12 , or no increase at all 13 following similar β-alanine supplementation protocols. In line with this, a recent meta-analysis including numerous studies assessing the effects of β-alanine supplementation on muscle carnosine showed that the method (HPLC vs. 1H-MRS) is a factor that significantly affects muscle carnosine outcomes (Rezende et al, submitted 34 ).…”

“…To be certain that HPLC is a reliable method for muscle carnosine determination and that it could be used as the reference in this study, we also examined its reliability, which showed excellent repeatability in all instances (i.e., intra-assay, inter-extract, and inter-biopsy). www.nature.com/scientificreports www.nature.com/scientificreports/ The present investigation revealed important methodological issues that must be considered when interpreting muscle carnosine values obtained in vivo by 1H-MRS. Due to the small signal amplitude [14][15][16][17] , we sought to be certain that the carnosine signal is quantifiable across the entire physiological range, including the expected values for the lowest and highest extremes of human population, such as those reported in vegetarians 9 and bodybuilders 22 . In this regard, 1H-MRS showed excellent linearity when carnosine is quantified in phantoms containing pure carnosine, as well as a clear ability to detect and quantify carnosine even in the lowest range.…”

“…One explanation for the larger variation of 1H-MRS is the non-homogeneity of carnosine distribution in the skeletal muscle. Carnosine content is greater in type II than type I muscle fibres 9 ; therefore, the inevitable change in muscle site when performing two 1H-MRS, albeit small, may cause sampling sites to have different fiber type composition, adding a source of measurement error. However, slight changes in sampling sites likely occurred with muscle biopsies and, yet, the variation for HPLC was lower.…”

Papel da atividade muscular sobre a regulação do conteúdo de carnosina em resposta à suplementação de beta-alanina: um estudo em atletas com lesão medular

“…Além de evidências produzidas através de experimentos in vitro (SEVERIN, KIRZON e KAFTANOVA, 1953;BEGUM, CUNLIFFE e LEVERITT, 2005), evidências indiretas corroboram o relevante papel da carnosina na regulação do pH intramuscular. Dentre elas, podemos destacar as maiores concentrações do dipeptídeo encontradas no músculo de atletas velocistas em comparação com atletas de endurance e controles não treinados (PARKHOUSE et al, 1985), bem como os elevados valores encontrados em fibras do tipo II (23.2 mmol‧kg -1 de músculo seco), até duas vezes maiores em relação às fibras oxidativas do tipo I (10.5 mmol‧kg -1 de músculo seco) (HARRIS, 1998;KENDRICK et al, 2009;SALLES PAINELLI et al, 2018). Cabe dizer que esforços de alta intensidade demandam altas taxas de transferência de energia por vias anaeróbias, processo este que gera grande acúmulo de íons H + e, portanto, redução do pH muscular.…”

“…De fato, acreditava-se que o treinamento físico, em especial os de alta intensidade, poderiam promover adaptações no sentido de elevar a capacidade tamponante muscular através do aumento da síntese de carnosina. Recentemente, em outro estudo conduzido no nosso laboratório, foi mostrado que o treinamento intervalado de alta intensidade promove aumento do conteúdo muscular de carnosina independentemente da ingestão de alimentos fontes de dipeptídeos histidínicos(SALLES PAINELLI et al, 2018). Portanto, acreditava-se que em atletas, a resposta a suplementação poderia ocorrer em menor magnitude, considerando que nestes indivíduos o conteúdo muscular de carnosina em condições basais geralmente está acima da média do restante da população.…”