PMID- 38149561 OWN - NLM STAT- MEDLINE DCOM- 20231228 LR - 20231228 IS - 0304-4920 (Print) IS - 0304-4920 (Linking) VI - 66 IP - 6 DP - 2023 Nov-Dec TI - Beta-hydroxy-beta-methylbutyrate supplementation preserves fat-free mass in collegiate boxers during acute body mass loss. PG - 485-493 LID - 10.4103/cjop.CJOP-D-23-00074 [doi] AB - Acute body mass loss before competitions in combat sports usually leads to loss in fat-free mass. Beta-hydroxy-beta-methylbutyrate (HMB) has been shown to increase skeletal muscle mass and muscle strength in various muscle wasting conditions. This study investigated the effect of HMB supplementation on body composition and sport-specific performance in well-trained boxers consuming a hypocaloric diet. Twelve male college boxers were divided into the HMB and placebo (PLA) groups using a body weight-matched single-blind parallel design. The study comprised a 6-day weight loss period (days 1-6), followed by a 3-day competition period (days 7-9). The participants in both the groups consumed 16 kcal/kg/day, including 1.6-1.7 g/kg of carbohydrates, 1.2-1.3 g/kg of protein, and 0.45-0.5 g/kg of fat during the 9-day period. The HMB group consumed 3 g/day HMB. Body composition measurement, isometric mid-thigh pull (IMTP), and a simulated boxing match were performed at baseline and on days 7, 8, and 9. Fasting blood samples were collected on the day before day 1 and on days 7, 8, and 9. Body mass was significantly decreased after the 6-day weight loss period (HMB group: baseline: 69.4 +/- 11.2 kg, day 7: 67.1 +/- 11.2 kg; PLA group: baseline: 68.6 +/- 12.1 kg, day 7: 65.7 +/- 11.5 kg, P < 0.05) while it was unchanged on the 3-day competition period in both the groups. Fat-free mass in the HMB group was maintained throughout the 9-day period (baseline: 56.7 +/- 9.3 kg, day 7: 56.3 +/- 8.7 kg, day 9: 55.8 +/- 9.5 kg) whereas it significantly decreased on days 7 and 9 compared to the baseline in the PLA group (baseline: 55.2 +/- 6.4 kg, day 7: 54.1 +/- 6.6 kg, day 9: 54.0 +/- 6.6 kg, P < 0.05). In the PLA group, the average and maximal heart rates in round 1 and the average heart rate in round 2 on days 8 and 9 were significantly lower than those at baseline, while these parameters were unchanged in the HMB group. The maximal force and the rate of force development in the IMTP remained unchanged among the different timepoints in both the groups. The blood biochemical parameters were similar at any timepoint between the PLA and HMB groups. HMB supplementation during acute weight loss may preserve fat-free mass and maintain heart rate response in subsequent simulated matches in well-trained boxers. In addition, HMB supplementation had a nonsignificant effect on glucose, fat, and protein metabolism during energy restriction. FAU - Chang, Chen-Kang AU - Chang CK AD - Department of Sport Performance, National Taiwan University of Sport, Taichung, Taiwan. FAU - Kao, Shih-Yen AU - Kao SY AD - Department of Sport Performance, National Taiwan University of Sport, Taichung, Taiwan. FAU - Wang, Chung-Yuan AU - Wang CY AD - Department of Combat Sport, National Taiwan University of Sport, Taichung, Taiwan. LA - eng PT - Journal Article PT - Randomized Controlled Trial PL - India TA - Chin J Physiol JT - The Chinese journal of physiology JID - 7804502 RN - 3F752311CD (beta-hydroxyisovaleric acid) RN - 0 (Polyesters) SB - IM MH - Humans MH - Male MH - Body Composition MH - *Diet, Reducing MH - *Dietary Supplements MH - Muscle, Skeletal/physiology MH - Obesity MH - Polyesters/pharmacology MH - Single-Blind Method MH - Weight Loss OTO - NOTNLM OT - Body composition OT - boxing OT - isometric mid-thigh pull OT - simulated boxing match COIS- None EDAT- 2023/12/27 12:41 MHDA- 2023/12/28 06:42 CRDT- 2023/12/27 06:46 PHST- 2023/12/28 06:42 [medline] PHST- 2023/12/27 12:41 [pubmed] PHST- 2023/12/27 06:46 [entrez] AID - ChinJPhysiol_2023_66_6_485_389333 [pii] AID - 10.4103/cjop.CJOP-D-23-00074 [doi] PST - ppublish SO - Chin J Physiol. 2023 Nov-Dec;66(6):485-493. doi: 10.4103/cjop.CJOP-D-23-00074.