Maria F. Navarrete1, Steven B. Machek1,2, Jeffrey L. Heileson2, Dillon R. Harris2, Emilia E. Zawieja,3 Dylan T. Wilburn2, Christopher D. Hulsey2, Jason M. Cholewa4, & Darryn S. Willoughby, FACSM2,5

1University of the Ozarks, Clarksville, AR; 2Baylor University, Waco, TX; 3The Poznań University of Life Sciences, Poznań, Poland; 4University of Lynchburg, Lynchburg, VA; 5University of Mary Hardin-Baylor, Belton, TX

Blood flow restriction (BFR) training and betaine supplementation are both touted for their ability to independently augment serum growth hormone (GH), as well as subsequent insulin-like growth factor-1 (IGF-1) concentrations. Furthermore, betaine supplementation may augment blood flow restriction (BFR) training-mediated metabolic stress and mechanical tension via osmolyte-associated protein protection and attenuated fatigue. PURPOSE: to compare the impacts of a potential BFR-betaine synergy on circulating post-exercise GH and IGF-1 concentrations. METHODS: Eighteen recreationally trained males (25±5y) were randomized in double-blind fashion to supplement 6g/day of either betaine anhydrous (BET) or identically dosed cellulose placebo (PLA) for 14-days. Subsequently, all subjects performed four standardized sets of one-leg press and two additional sets to muscular failure on both legs in a counter-balanced and crossover design. Specifically, one leg performed standard high-load (HL; 70%1RM) exercise and contralateral limb underwent BFR (LL-BFR; 20%1RM) training at 80% arterial occlusion pressure. Serum growth hormone (GH) and insulin-like growth factor-1 concentrations were analyzed before (PRE) and 30-minutes post-exercise (POST30M), subsequently quantified via ELISA. The changes in serum hormones from baseline (∆GH and ∆IGF-1) were assessed via separate two-way mixed model ANOVA with repeated measures at a significance level of p<.05. RESULTS: Analysis failed to detect any main or interaction effects for ∆GH. Despite statistically equivocal main exercise condition and interaction effects, the supplement-specific change from baseline in serum IGF-1 was significantly (p=.042; ηp2=.247) higher in BET (105.4±34.0ng/mL to 114.6±32.6ng/mL) versus PLA (136.6±45.1 to 129.1±37.7ng/mL). Incidentally, serum ∆IGF-1 failed normality assumptions, and thus the aforementioned significant finding was confirmed via a exercise condition-collapsed non-parametric Mann-Whitney U test (p=.029; R2=.132). CONCLUSION: Although these data fail to support a BFR-betaine synergy, they otherwise support BFR as a viable training modality and further substantiate the growing literature regarding betaine’s ostensibly anabolic potential.

ACKNOWLEDGEMENTS: The present research was partially funded by the Baylor University Health, Human Performance, and Recreation Doctoral Dissertation Research Grant and the Polish National Science Centre under Grant DEC2017/27/N/NZ9/00750 (approximately 40% and 60% of total funding, respectively). Furthermore, the authors would like to thank Dr. Mike DeBord from B3 Sciences and Jack Owoc from Vital Pharmaceuticals for generously donating the experimental cuffs and supplement, respectively, to assist in the completion of this investigation.

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