HMB COMBINED WITH HIGH-INTENSITY FUNCTIONAL EXERCISE IMPROVE PERFORMANCE AND AEROBIC CAPACITY IN TRAINED MALES

PURPOSE: Beta-hydroxy-beta-methylbutyrate (HMB) is supposed to facilitate protein synthesis and thus supports nutritional status, physical capacity and exercise performance. It was hypothesized that 3-wk supplementation with free liquid HMB form (90 mgHMB·kg-1Fat-free mass[FFM]) will result in the improvement in the performance and aerobic capacity, and the magnitude of these changes will be amplified after introducing high-intensity functional training (HIFT) stimuli. METHODS: The randomized double-blind placebo-controlled parallel study was performed in the group of 21 trained male athletes aged 31.1 ± 9.3 yrs. Participants were randomly allocated into the HMB (n = 11) or the placebo (PLA; n = 10) group. The study protocol included two 3-wk periods: 1) supplementation period (SUP) - ingestion of HMB/PLA and performing usual training cycle, and 2) SUP + FGB period - ingestion of HMB/PLA and implementing the additional exercise stimuli - two Fight Gone Bad (FGB) workouts/wk. Testing were performed at baseline (BAS), and after completion of SUP and SUP + FGB. The incremental cycling test was performed. Oxygen uptake (VO2), carbon dioxide exhalation and heart rate (HR) were recorded. The following indices were evaluated: time to exhaustion (TEXH), maximal VO2 uptake (VO2MAX), respiratory quotient (RQ), maximal HR (HRMAX) and power (PMAX), as well as time to ventilatory threshold (TVT), and corresponding VT values: VO2VT, RQVT, HRVT and PVT. RESULTS: In the HMB group: 1) there were significant linear increases in TEXH (BAS: 814 ± 48 s, SUP: 849 ± 48 s, SUP + FGB: 879 ± 47 s; p < 0.001) and PMAX (BAS: 317 ± 20 W, SUP: 331 ± 20 W, SUP + FGB: 344 ± 19 W; p < 0.001) across study visits; and 2) at SUP + FGB VO2MAX (BAS: 3907 ± 420 mL·min-1, SUP: 4031 ± 340 mL·min-1, SUP + FGB: 4209 ± 465 mL·min-1; p = 0.017), and TVT (BAS: 609 ± 72 s, SUP: 621 ± 56 s, SUP + FGB: 636 ± 73 s; p = 0.022) were significantly higher compared to BAS. Moreover, at SUP HRMAX, HRVT and RQVT were higher in the HMB compared to the PLA group. CONCLUSIONS: HMB supplementation significantly improved performance and aerobic capacity indices, and HIFT stimuli amplified the effects. HIFT-stimuli provided no advantages regarding aerobic capacity in trained males (PLA group), unless combined with supplementation with high individual doses of HMB established relative to FFM. Supported by: This study was funded by the National Science Centre, Poland. K.D.-M has received research grant from the Polish National Science Centre (grant number 2018/31/D/NZ7/00803).