Physiological and performance effects of a probiotic supplementation on runners under heat stress : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Human Nutrition, Massey University, Palmerston North, New Zealand
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Date
2021
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Massey University
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Abstract
Background: Interest in the role of probiotics in gut health and wellbeing has grown rapidly over the last 10 years, however research into the use of probiotics in exercise as a potential ergogenic aid is limited. Previous literature has identified several mechanisms that may be behind the beneficial effects conferred by a range of probiotic strains on host health, such as immune function, gut regulation, inflammatory responses and cognition. It appears that a few strains have shown to exert ergogenic potential although Fonterra’s proprietary strains have yet to be investigated in this space. Research in this area may lead to a potential new therapeutic option for athletes in the ever expanding, multimillion dollar sport nutrition supplement industry. Aim: To investigate if 4 weeks of Lactocaseibacillus rhamnosus HN001 and Bififidobacterium animalis ssp. lactis HN019 probiotic supplementation would influence exercise performance of male runners under heat stress. Further, physiological parameters, including fluid loss, core temperature and HR were also investigated during the exercise test. Methods: In a randomised, double-blinded, crossover study, seven male runners completed 4 weeks of dual strain probiotic or placebo supplementation followed by a 1 hour running trial in a heat chamber (30°C, 50% RH) at the end of each supplementation period. Participants ran on a treadmill at 70% of their ventilatory threshold (VT) for a 45-min pre-load phase followed immediately by a 15-min self-paced time trial. HR, core temperature and fluid loss were recorded throughout the experimental trial. Participants completed a 3-week washout period in between the two supplementation periods. Results: Four weeks of dual probiotic supplementation did not affect exercise performance in male runners under heat stress as determined by a 15-min time trial (p=0.63). Physiological measures were also unaffected following the supplementation period. Reliability data showed good reliability for performance (<5% CV). Conclusion: No ergogenic effect was conferred by the combination of these two strains, B. lactis HN019 and L. rhamnosus HN001, following 4 weeks’ supplementation. Physiological measures of HR, fluid loss and core temperature, taken during the experimental trial were also negligible. It is likely either the dose, small sample size, probiotic strains or combination of all three played a role in the absence of improvement to performance and physiological measures. The reliability of test-retest (CV< 5%) reflected the robust nature of the study design despite several limitations, some of which were to be expected with running a study through COVID restrictions. However, future research should explore a dose dependent relationship, alongside increasing the sample size and investigating the possible interaction between multi strain probiotic interventions.