The Effects of Leucine Metabolites in Performance, Body Composition and Biochemical Markers of Muscle Damage
Condition: Resistance Training
Study type: Interventional

Summary: 
      This study aimed to conduct a double-blind randomized pragmatic trial to evaluate the effects
      of off-the-shelf leucine metabolite supplements HMB-FA, HMB-Ca, alfa-HICA, on resistance
      training-induced changes in body composition, performance and biochemical markers of muscle
      damage. The investigators' working hypothesis is that so long as subjects adhered to a diet
      containing adequate energy and dietary protein, there would be no differences between those
      receiving the leucine metabolites - HMB-FA, HMB-Ca and alfa-HICA - when compared to a placebo
      consuming group.
    

Detailed description: 
      This was a randomized, double blind, placebo-controlled study with additional control of
      diet. The investigators compared the effect of 8 weeks of supplementation with HMB-FA,
      HMB-Ca, or alfa-HICA on performance, body composition, and biochemical markers of muscle
      damage. The study involved fifty-three participants engaged in resistance training for at
      least one year (≥3 training sessions per week).

      Performance measures - To evaluate aerobic performance an incremental test to volitional
      exhaustion was performed. Peak power and strength was assessed by maximum strength and the
      participants also performed a Wingate and vertical jump tests. Perceived performance and
      recovery was measured by the perceived recovery status scores in training days. This tool
      allowed to evaluate both fatigue, general muscle soreness, sleep quality, stress levels and
      mood throughout the study. Performance tests were performed at baseline, prior to the
      beginning of the study, and at the end of weeks 4 and 8, in a fed state (a meal replacement
      bar was provided to participants before the tests).

      Body composition measures - To evaluate body composition a dual-energy X-ray absorptiometry
      (DXA) scan was performed; Muscle thickness was measured by ultrasonography; Total body water
      and both the extracellular water and intracellular water were assessed by bioelectrical
      impedance spectroscopy (BIS). These tests were performed at baseline and at the end of weeks
      4 and 8, with participants reporting to the lab in a fasted state, refraining from exercise,
      alcohol or stimulant beverages for at least 8 h.

      Biochemical markers of muscle damage - To assess biochemical markers (total testosterone and
      cortisol, creatine kinase, insulin-like growth factor 1, growth hormone), blood was collected
      at baseline and at the end of weeks 4 and 8, in a fasted state with participants also
      refraining from exercise, alcohol or stimulant beverages for at least 12 h.

      Training protocol - The training program was designed according to the guidelines for
      hypertrophy type of resistance training for intermediate-trained individuals and consisted on
      3 sessions per week during an 8-week period.

      Statistics - sample size was calculated through an a priori power analysis (G*Power Version
      3.1.9.2, Heinrich Heine Universitat Dusseldorf, Germany), based on FFM changes from previous
      studies and power of 0.80. Statistical analysis will be performed using IBM SPSS statistics
      version 22.0 (IBM, Chicago, Illinois, USA). Normality of the distribution of variables will
      be tested by Shapiro-Wilk test. Baseline characteristics between groups were analyzed by a
      1-way analysis of variance (ANOVA) since normality was observed. Time and time x group
      interactions will be evaluated by repeated-measures ANOVA. The equality of the matrix of
      variance and sphericity will be explored with the Levene F test and Mauchly's test,
      respectively. Overall significance level for α was set at p ≤ 0.05.
    

Intervention name(s): HMB-FA; HMB-Ca; alfa-HICA; Placebo comparator
Intervention type(s): Dietary Supplement; Dietary Supplement; Dietary Supplement; Other
Intervention description(s): One gram of HMB-FA was ingested before exercise, and two grams were ingested at subsequent meals (1 g per meal). At rest days supplement was administered 1 g per meal. The total duration of the intervention was 8 weeks.; One gram of HMB-Ca was ingested before exercise, and two grams were ingested at subsequent meals (1 g per meal). At rest days supplement was administered 1 g per meal. The total duration of the intervention was 8 weeks.; Five hundred miligram of alfa-HICA was ingested before exercise, and one gram was ingested at subsequent meals (500 mg per meal). At rest days supplement was administered 500 mg per meal. The total duration of the intervention was 8 weeks.; One gram of magnesium stearate was ingested before exercise, and two grams were ingested at subsequent meals (1 g per meal). At rest days placebo was administered 1 g per meal. The total duration of the intervention was 8 weeks.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Basic Science
Keywords: Leucine metabolites; Resistance training; Hypertrophy; Strength; Supplement