Alissa Wika1, Kyle Reason1, James Green, FACSM1, Lauren Killen1, Matthew McAllister2, Hunter Waldman1. 1University of North Alabama, Florence, AL. 2Texas State University, San Marcos, TX.

BACKGROUND: Astaxanthin (AX), a carotenoid found in marine species has been found to positively impact metabolic markers, including reducing inflammation, hypertension, diabetes, and even some types of cancer. Additionally, studies focused on healthy individuals have shown AX may improve fat oxidation rates and spare endogenous carbohydrates, which in turn should improve markers of metabolic flexibility. However, to date, no studies have examined the impact of AX in an overweight cohort. Therefore, this study assessed the impact AX supplementation on markers of metabolic flexibility in overweight individuals (≥25 bodyfat percentage). METHODS:Subjects supplemented with 12 mg AX or placebo (PLA) for 4 weeks in between pre and post trials. Pre and post trials included anthropometric measurements (height, mass, bodyfat percentage, and blood pressure) and a graded exercise test (GXT) on the Velotron bike. The GXT included 6 stages, each lasting 5 min, with the first being a resting stage. Stage 2 started at 30 W (females) and 50 W (males). Resistance increased 15 W after each stage ended, completing a total of 90 W (females) and 110 W (males). Following completion of 6 stages, resistance increased by 15 W every minute, until volitional exhaustion where VO2peak was recorded. During the last 30 s of Stages 1-6, subjects had their finger pricked for the measurement of capillary lactate and glucose. In addition, VO2, VCO2, heart rate (HR), respiratory exchange ration (RER), and overall ratings of perceived exertion (RPE) were recorded at the end of each stage. RESULTS: There were no changes found in fat oxidation rates, blood lactate levels, or bodyfat percentage (all P > 0.05). However, there was a significant decrease in carbohydrate oxidation from pre to post supplementation AX only (P = 0.02, d = 0.23; ~8%). Additionally, the AX group also showed a dramatic decrease in exercising heart rate from pre to post supplementation (P < 0.001, d = 0.46, ~7%, 9 bpm). Although no changes were observed in primary markers of metabolic health (i.e. fat oxidation rates, bodyfat percentage), the significant decrease in HR following AX supplementation, at any given absolute intensity during cycling, provides some implications for reducing cardiac strain in overweight individuals during exercise and may have implications for future clinicians.

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