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THE LONGITUDINAL EFFECTS OF BETA-ALANINE SUPPLEMENTATION ON TIME TO EXHAUSTION AND LOWER-BODY ISOMETRIC TORQUE IN MASTERS FEMALE CYCLISTS

Abstract

Jordan M. Glenn1,2, Rodger Stewart1,2, Nicole E. Moyen1, Carly Arnold1, Landon Lavene1, Mikaila Davis1, Aaron Martinez1, Lauren Wethington1,2 & Michelle Gray1,2

University of Arkansas – 1Human Performance Lab, 2Office for Studies on Aging, Fayetteville, Arkansas

Longitudinal supplementation of beta-alanine (BA) increases exercise performance presumably due to increases in the intramuscular pH buffer, carnosine. With regards to BA supplementation, females are more sensitive to carnosine increases and these results are further pronounced in trained muscle. Taking into account the fact that baseline intramuscular carnosine levels also naturally decrease with age, trained, older females may experience the most significant benefits from BA supplementation. However, the effects of BA on exercise performance in female masters athletes (MA) are unknown. PURPOSE: The purpose of this study was to examine the longitudinal effects of BA supplementation on cycling time to exhaustion (TTE) and lower-body isometric torque (ISOtq) in female MA cyclists. METHODS: Sixteen female MA (age = 53.8 ± 1.5 years, height = 162.63 ± 2.74 cm, weight = 64.39 ± 5.29 kg) with a minimum of 2-years competitive cycling experience participated in this double-blind, randomized study. Participants were randomized into two groups (PLA = 8g dextrose; BA = 800mg + 8g dextrose) before completing TTE evaluation at 120% of pre-determined VO2peak values, and dominant leg ISOtq. Participants supplemented 4 times/day over 4 weeks. TTE and ISO were revaluated each week over the 4-week intervention. RESULTS: There were no initial significant differences between groups for demographic, TTE, or ISOtq variables (p > 0.05). Two-way repeated measures ANOVA revealed that after 4 weeks of BA supplementation, TTE was significantly increased in the BA group compared to PLA (p < 0.05). Univariate analyses indicated that at week 4, participants consuming BA performed significantly better (24% increase from baseline) during TTE compared to PLA (p < 0.01). No differences were observed for TTE during the other intermittent weeks. When comparing ISOtq, no significant differences existed at any time point between the two groups (p > 0.05). CONCLUSION: Four-weeks of BA supplementation increased cycling TTE in female MA with no effects on lower-body ISOtq. As significant results were not observed until the 4-week time-point, this indicates BA must be loaded a minimum of 4 weeks for positive results to be observed in older, trained females although they may experience more sensitive responses with regards to increases in intramuscular carnosine bioavailability. Future research directions should evaluate the mechanistic properties influencing these positive increases in performance as carnosine concentrations can only be evaluated via muscle biopsy analysis or proton magnetic resonance spectroscopy.

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