Leucine metabolites do not induce changes in phase angle, bioimpedance vector analysis patterns, and strength in resistance trained men.

We aimed to assess the effects of off-the-shelf leucine metabolite supplements on phase angle (PhA), bioimpedance vector analysis (BIVA) patterns and strength during an 8-week resistance training protocol. Fifty-three male participants were allocated into 4 groups: α-hydroxyisocaproic acid (n = 12, age = 30.9 ± 9.3 years), ß-hydroxy-ß-methylbutyrate free acid (n = 12, age = 31.0 ± 9.3 years), calcium ß-hydroxy-ß-methylbutyrate (n = 15, age = 32.1 ± 5.2 years) or placebo (n = 14, age = 28.9 ± 6.6 years). Bioimpedance parameters and 1-repetition maximum (1RM) for back squat and bench press were assessed at baseline and at the end of weeks 4 and 8. Additionally, fat-free mass and fat mass were evaluated by dual-energy X-ray absorptiometry. No statistically group by time interactions were found, even adjusting for age. PhA and vector did not change over the training period, while time-dependent increases were observed for 1RM back squat and 1RM bench press. A direct association was observed between PhA and 1RM bench press changes (whole sample), while PhA and strength were correlated throughout the study, even when adjusting for fat-free mass and percentage of fat mass. Leucine metabolites have no effect on PhA, BIVA patterns or strength during an 8-week resistance training program, in resistance trained subjects. The trial was registered at ClincicalTrials.gov: NCT03511092. Novelty: Supplementation with leucine metabolites is not a supplementation strategy that improves bioelectrical phase angle, cellular health, and strength after an 8-week resistance training program. When consuming a high protein diet, none of the α-hydroxyisocaproic acid, ß-hydroxy-ß-methylbutyrate free acid, and calcium ß-hydroxy-ß-methylbutyrate metabolites resulted in an ergogenic effect in resistance trained men.

Muscle thickness and echo-intensity changes of the quadriceps femoris muscle during a strength training program.

INTRODUCTION: Ultrasound (US) has an important role in musculoskeletal (MSK) evaluation, allowing the study of muscle morphology and function. Muscle thickness (MT) and muscle echo-intensity (EI) are two important parameters that may quantify muscle structural adaptations to a variety of stimuli. The aim was to explore the potential of quantitative US imaging for assessing the adaptations and responses of the muscle tissue to increased contractile activity using B-mode US. This study was centred on the quadriceps femoris muscle contractile activity on MT and EI. METHODS AND MATERIALS: Twenty-eight young male adults participated in the study, divided in a control group and two training groups performing concentric or eccentric strength training, respectively. The effect of a 15-week strength program was studied on MT and EI in several regions of the heads of the quadriceps femoris using B-mode US. All images acquisitions and measurements were done by the same experience sonographer. RESULTS: Strength training resulted in an increase of MT at all muscles and sites (p < 0.05), except the VM. Strength training failed in changing EI in most of the quadriceps femoris, except in the VI and some regions of the VL. No statistically significant differences were observed in our quantitative US parameters between concentric and eccentric training (p > 0.05). CONCLUSION: These results emphasise the value of MT as a quantifiable muscle US method for evaluating muscle adaptation to exercise training. However, the inconsistency of the EI values indicates that more studies are needed to develop it as an accurate diagnostic tool.

Upper body force production after a low-volume static and dynamic stretching.

This study investigated the acute effect of a low-volume static and dynamic stretching on maximal isometric peak force (MIPF), time to maximal isometric force (TMIF), rate of force production (RFP) and average amplitude of the surface EMG (AvgEMG) of the main agonist muscles acting on the bench press maximum isometric force exercise. Thirty subjects were randomly divided into three groups: static stretch (SG: 22.8 ± 5.6 years, 176.6 ± 3.5 cm, 74.4 ± 5.9 kg), dynamic stretch (DG: 21.4 ± 3.9 years, 178.4 ± 7.2 cm, 71.7 ± 8.2 kg) and control group (CG: 20.4 ± 3.6 years, 179.8 ± 5.8 cm, 74.4 ± 9.8 kg). SG performed two 30-s repetitions and DG performed 10 repetitions of each of the two different exercises for the pectoralis major and triceps brachii. The MIPF, TMIF, RFP and AvgEMG of the pectoralis major (sternocostal part) and triceps brachii (long and lateral head) were measured before and immediately after the stretching protocols. A significant decrease in the MIPF from pre- to post-stretching was observed in both SG (p <0.001) and DG (p <0.05). No significant differences were found in the CG for all force parameters. No significant differences in the TMIF and RFP from pre- to post-stretching were found in the three groups. The SG showed a significant (p <0.05) decrease in the AvgEMG of the three muscles, whereas no significant differences were found for the DG and CG. These findings suggest that a low-volume static and dynamic stretching adversely affects efforts of muscle maximal strength of the upper limb muscles studied, but it does not seem to affect TMIF or RFP.

Analysis of kinematics of the lower limb during step exercise.

The motion of lower extremity joints is one of the mechanisms by which mechanical load is attenuated. The main purposes of this study were to characterize the motion of the right lower limb in a group of 18 women experienced in step exercise, when performing selected step patterns, and to investigate the differences that exist between four stepping rate conditions (125, 130, 135, and 140 beats per minute) and between four step patterns (basic step, knee lift, run step, and knee hop). The parameters explored were the range-of-movement and angular velocity of hip, knee, and ankle joints at initial contact and peak values. The four movement patterns analyzed presented different kinematical profiles, but no profiles were influenced by stepping rate. Stepping rate and step pattern had more effect on range of motion of ankle and knee joints, and on the angular velocity of knee and hip joints. To prevent injury, proper instruction should be provided in relation to foot placement on the step bench and on the ground.