Both BA and BA+HIS groups showed significantly increased carnosine concentrations after 23 days of supplementation (BA: soleus p<0.001 (+57.2%), gastrocnemius p=0.002 (+34.6%). BA+HIS: soleus p<0.001 (+54.0%), gastrocnemius p=0.004 (+33.1%)), in contrast to the HIS group of which the carnosine concentration remained constant during the supplementation period (soleus p=0.894 (+5.0%), gastrocnemius p=0.528 (+4.0%)). This is the first study to investigate the effect of L-histidine supplementation on muscle carnosine content. In contrast to the animal data, histidine supplementation does not induce carnosine loading in human muscles. Furthermore, combined supplementation with beta-alanine and L-histidine has no additional effect compared to beta-alanine supplementation alone. Collectively, these data confirm that beta-alanine is the rate-limiting factor for carnosine synthesis in humans. References Derave W et al (2010). Sports medicine 40: 247–63. Tamaki N et al (1977). Journal of Nutritional Science and Vitaminology 23: 331-340. Dunnett and Harris (1999). Equine Vet J (Suppl.) 30: 499-504 park SW et al (2013). Japan Poultry Science 50: 251-256. Harris RC et al (2006). Amino Acids 30(3): 279–289. The influence of a mild thermal challenge and severe hypoxia on exercise performance and serum BDNF. Jeroen Van Cutsem1, Nathalie Pattyn1,4, Dirk Vissenaeken3, Gino Dhondt3, Kevin De Pauw1, Cajsa Tonoli1, Romain Meeusen1,5, Bart Roelands1,2. 1 Department of Human Physiology, Vrije Universiteit Brussel, Brussels, Belgium 2 Fund for Scientific Research Flanders (FWO) 3 Center for Aviation Medicine, Military Hospital Queen Astrid, Brussels, Belgium 4 Vital Signs and Performance Monitoring, Royal Military Academy, Brussels, Belgium 5 School of Public Health, Tropical Medicine and Rehabilitation Sciences, Abstract Aim To examine the isolated and combined effects of severe hypoxia and a mild thermal challenge on performance, physiological measures, cognition and serum brain derived neurotrophic factor (BDNF). Methods Nine trained male athletes (Age: 23±3y; Wmax: 333±45W) completed four experimental trials (CON: 15°C/0m, ALT: 15°C/3800m, TEMP: 25°C/0m, ALT+TEMP: 25°C/3800m) in a double blind, randomized, cross-over design. Subjects cycled for 30min in a self-paced test starting at 75%Wmax, their goal was to ‘perform as much work as possible in 30min’. Power output, heart rate, blood lactate, pulse oximetry, core and skin temperature, thermal sensation, ratings of perceived exertion (RPE), reaction time (RT) and BDNF were assessed. Results Subjects produced a significantly lower amount of work in 30min due to temperature (CON: 434±69kJ; TEMP: 420±75kJ; P=0.029) and altitude (CON: 434±69kJ; ALT: 298±51kJ; P<0.001). RPE-scores did not differ between trials (P>0.05). Altitude increased mean RT (P=0.022; 282±28ms at sea level; 289±32ms at altitude) and RT variability (P=0.020; 44±3ms at sea level: 50±4ms at altitude). Exercise increased BDNF (P=0.005; PRE: 21.8±8.4ng/mL; POST: 26.5±10.9ng/mL). However nummer 2 | juli 2015 | Sport & Geneeskunde 43 Pagina 42
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