Effects of six weeks of beta-hydroxy-beta-methylbutyrate (HMB) and HMB/creatine supplementation on strength power, and anthropometry of highly trained athletes
ABSTRACT This study investigated the effects of 6 weeks of dietary supplementation of beta-hydroxy-beta-methylbutyrate (HMB) and HMB combined with creatine monohydrate (HMBCr) on the muscular strength and endurance, leg power, and anthropometry of elite male rugby league players. The subjects were divided into a control group (n = 8), a HMB group (n = 11; 3 g.d(-1)) or a HMBCr group (n = 11; 12 g.d(-1) with 3 g HMB, 3 g Cr, 6 g carbohydrates). Three repetition maximum lifts on bench press, deadlifts, prone row, and shoulder press, maximum chin-up repetitions, 10-second maximal cycle test, body mass, girths, and sum of skinfolds were assessed pre- and postsupplementation. Statistical analysis revealed no effect of HMB or HMBCr on any parameter compared with presupplementation measures or the control group. HMB and HMBCr were concluded to have no ergogenic effect on muscular strength and endurance, leg power, or anthropometry when taken orally by highly trained male athletes over 6 weeks.
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ABSTRACT: BACKGROUND AND AIM: Strength and power are crucial components to excelling in all contact sports; and understanding how a player's strength and power levels fluctuate in response to various resistance training loads is of great interest, as it will inevitably dictate the loading parameters throughout a competitive season. This is a systematic review of training, maintenance and detraining studies, focusing on the development, retention and decay rates of strength and power measures in elite rugby union, rugby league and American football players. SEARCH STRATEGIES: A literature search using MEDLINE, EBSCO Host, Google Scholar, IngentaConnect, Ovid LWW, ProQuest Central, ScienceDirect Journals, SPORTDiscus™ and Wiley InterScience was conducted. References were also identified from other review articles and relevant textbooks. From 300 articles, 27 met the inclusion criteria and were retained for further analysis. STUDY QUALITY: Study quality was assessed via a modified 20-point scale created to evaluate research conducted in athletic-based training environments. The mean ± standard deviation (SD) quality rating of the included studies was 16.2 ± 1.9; the rating system revealed that the quality of future studies can be improved by randomly allocating subjects to training groups, providing greater description and detail of the interventions, and including control groups where possible. DATA ANALYSIS: Percent change, effect size (ES = [Post-Xmean - Pre-Xmean)/Pre-SD) calculations and SDs were used to assess the magnitude and spread of strength and power changes in the included studies. The studies were grouped according to (1) mean intensity relative volume (IRV = sets × repetitions × intensity; (2) weekly training frequency per muscle group; and (3) detraining duration. IRV is the product of the number of sets, repetitions and intensity performed during a training set and session. The effects of weekly training frequencies were assessed by normalizing the percent change values to represent the weekly changes in strength and power. During the IRV analysis, the percent change values were normalized to represent the percent change per training session. The long-term periodized training effects (12, 24 and 48 months) on strength and power were also investigated. RESULTS: Across the 27 studies (n = 1,015), 234 percent change and 230 ES calculations were performed. IRVs of 11-30 (i.e. 3-6 sets of 4-10 repetitions at 74-88 % one-repetition maximum [1RM]) elicited strength and power increases of 0.42 % and 0.07 % per training session, respectively. The following weekly strength changes were observed for two, three and four training sessions per muscle region/week: 0.9 %, 1.8 % and 1.3 %, respectively. Similarly, the weekly power changes for two, three and four training sessions per muscle group/week were 0.1 %, 0.3 % and 0.7 %, respectively. Mean decreases of 14.5 % (ES = -0.64) and 0.4 (ES = -0.10) were observed in strength and power across mean detraining periods of 7.2 ± 5.8 and 7.6 ± 5.1 weeks, respectively. The long-term training studies found strength increases of 7.1 ± 1.0 % (ES = 0.55), 8.5 ± 3.3 % (ES = 0.81) and 12.5 ± 6.8 % (ES = 1.39) over 12, 24 and 48 months, respectively; they also found power increases of 14.6 % (ES = 1.30) and 12.2 % (ES = 1.06) at 24 and 48 months. CONCLUSION: Based on current findings, training frequencies of two to four resistance training sessions per muscle group/week can be prescribed to develop upper and lower body strength and power. IRVs ranging from 11 to 30 (i.e. 3-6 sets of 4-10 repetitions of 70-88 % 1RM) can be prescribed in a periodized manner to retain power and develop strength in the upper and lower body. Strength levels can be maintained for up to 3 weeks of detraining, but decay rates will increase thereafter (i.e. 5-16 weeks). The effect of explosive-ballistic training and detraining on pure power development and decay in elite rugby and American football players remain inconclusive. The long-term effects of periodized resistance training programmes on strength and power seem to follow the law of diminishing returns, as training exposure increases beyond 12-24 months, adaptation rates are reduced.Sports Medicine 03/2013; DOI:10.1007/s40279-013-0031-3 · 5.32 Impact Factor
Strength and conditioning journal 01/2010; 32(1):93-100. DOI:10.1519/SSC.0b013e3181c212b9 · 0.77 Impact Factor
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ABSTRACT: Position Statement: The International Society of Sports Nutrition (ISSN) bases the following position stand on a critical analysis of the literature on the use of beta-hydroxy-beta-methylbutyrate (HMB) as a nutritional supplement. The ISSN has concluded the following. 1. HMB can be used to enhance recovery by attenuating exercise induced skeletal muscle damage in trained and untrained populations. 2. If consuming HMB, an athlete will benefit from consuming the supplement in close proximity to their workout. 3. HMB appears to be most effective when consumed for 2 weeks prior to an exercise bout. 4. Thirty-eight mg.kg.BM-1 daily of HMB has been demonstrated to enhance skeletal muscle hypertrophy, strength, and power in untrained and trained populations when the appropriate exercise prescription is utilized. 5. Currently, two forms of HMB have been used: Calcium HMB (HMB-Ca) and a free acid form of HMB (HMB-FA). HMB-FA may increase plasma absorption and retention of HMB to a greater extent than HMB-CA. However, research with HMB-FA is in its infancy, and there is not enough research to support whether one form is superior. 6. HMB has been demonstrated to increase LBM and functionality in elderly, sedentary populations. 7. HMB ingestion in conjunction with a structured exercise program may result in greater declines in fat mass (FM). 8. HMB's mechanisms of action include an inhibition and increase of proteolysis and protein synthesis, respectively. 9. Chronic consumption of HMB is safe in both young and old populations.Journal of the International Society of Sports Nutrition 02/2013; 10(1):6. DOI:10.1186/1550-2783-10-6 · 1.50 Impact Factor