Gustavo H. Peixoto

The Effect of Double - Blind Carbohydrate Ingestion during 60 km of Self-Paced Exercise in Warm Ambient Conditions

This study evaluated double blind ingestions of placebo (PLA) versus 6% carbohydrate (CHO) either as capsules (c) or beverage (b) during 60 km self-paced cycling in the heat (32°C and 50% relative humidity). Ten well-trained males (mean ± SD: 26±3 years; 64.5±7.7 kg and 70.7±8.8 ml.kg−1.min−1 maximal oxygen consumption) completed four separate 60 km time trials (TT) punctuated by 1 km sprints (14, 29, 44, 59 km) whilst ingesting either PLAb or PLAc or CHOb or CHOc. The TT was not different among treatments (PLAb 130.2±11.2 min, CHOb 140.5±18.1 min, PLAc 143.1±29.2 min, CHOc 137.3±20.1 min; P>0.05). Effect size (Cohen’s d) for time was only moderate when comparing CHOb – PLAb (d = 0.68) and PLAb – PLAc (d = 0.57) whereas all other ES were ‘trivial’ to ‘small’. Mean speed throughout the trial was significantly higher for PLAb only (P<0.05). Power output was only different (P<0.05) between the sprints and low intensity efforts within and across conditions. Core and mean skin temperatures were similar among trials. We conclude that CHO ingestion is of little or no benefit as a beverage compared with placebo during 60 km TT in the heat.

Estudo da confiabilidade da força aplicada durante a mobilização articular ântero-posterior do tornozelo

Reliability Study on the Force Applied During Anteroposterior Mobilization of the Ankle Joint Background: Factors that contribute towards the efficiency of joint mobilization maneuvers is the intensity and reproducibility of the force applied during mobilization, by one or more examiners. Objective: To evaluate the intra and inter-examiner reliability of Maitland grade III and IV anteroposterior mobilization force on the ankle joint. Method: Two experienced examiners mobilized both ankles of thirty-five healthy subjects. A force platform was positioned under the calves of these subjects to detect the forces applied during the maneuvers. The signals were converted and recorded using the DasyLab 4.0 software. The maximum and minimum peak forces from the curves obtained were then analyzed. The intraclass correlation coefficient (ICC) was used to assess the intra and inter-examiner reliability. To evaluate any systematic error in the measurements, the paired t-test was utilized on the intra-examiner data and the t-test for independent samples for the inter-examiner data. The Bland & Altman method was used to assess the concordance limits for the measurements from the two examiners. Results: The data showed high intraexaminer reliability. The inter-examiner reliability was low and moderate for the maximum and minimum forces respectively, during anteroposterior mobilization of the ankle joint. Conclusions: These data suggest that the force applied during Maitland grade III and IV mobilization of the ankle joint presents high intra-examiner reliability and low inter-examiner reliability.

Viscoelastic stress relaxation in the hamstrings before and after a 10-week stretching program.

We investigated the viscoelastic stress relaxation response before and after a 10‐week hamstrings static stretch program. Methods: The maximal range of motion (ROMmax) and maximal torque (Torquemax) were assessed before and after a 10‐week stretching program. Six 30‐s static stretches at a predetermined torque were performed, and the relative change in stress relaxation was examined. Results: ROMmax and Torquemax increased by 53% and 82%, respectively (P < 0.001). The relative stress relaxation (RSR) decreased significantly for repetition 1 when comparing the pretest (25%) and posttest (21%) values (P = 0.003). A significant decrease was also observed for repetitions 2 and 3 (P < 0.014), with no significant difference in repetitions 4–6 (P > 0.056). Conclusions: Individuals who participated in a 10‐week hamstrings passive–static stretch program had a reduced RSR response. A higher stretch intensity or longer duration may be necessary to achieve RSRs similar to those reported before the stretch program. Muscle Nerve, 2015 Muscle Nerve 51:761–764, 2015

Space Creation Dynamics in Basketball Small-Sided Games:

Space creation dynamics (SCDs) describe actions players perform to create a scoring opportunity. This study compared SCDs and types of offense during three different three versus three (3vs.3) basketball small-sided games (SSGs) played in half court: 3vs.3 with man-to-man defense in half playing area (3vs.3HALF), 3vs.3 with man-to-man defense in full playing area (3vs.3FULL), and 3vs.3 with reduced shot clock (3vs.3RT). We also investigated the efficacy of SCDs in all SSGs and the reliability of SCDs in 3vs.3HALF. While the efficacy of SCDs did not differ among these SSGs, 3vs.3RT presented significantly more “space creation with ball dribbled” and “shot clock violations,” and less “on ball screens.” 3vs.3FULL presented no differences in the SCDs and types of offense compared with 3vs.3HALF. Reliability within 3vs.3HALF was higher for “space creation with ball dribbled,” “space creation without the ball,” “set offenses,” “fast breaks,” and “loss of ball during passing or dribbling.” We concluded that 3vs.3 basketball SSGs with different rules can be used for training different tactical behaviors important to formal games, especially since the 3vs.3HALF presented good reliability for many variables related to tactical behavior.

Exploratory factor analysis for differentiating sensory and mechanical variables related to muscle-tendon unit elongation.

ABSTRACT Background Stretching exercises are able to promote adaptations in the muscle-tendon unit (MTU), which can be tested through physiological and biomechanical variables. Identifying the key variables in MTU adaptations is crucial to improvements in training. Objective To perform an exploratory factor analysis (EFA) involving the variables often used to evaluate the response of the MTU to stretching exercises. Method Maximum joint range of motion (ROMMAX), ROM at first sensation of stretching (FSTROM), peak torque (torqueMAX), passive stiffness, normalized stiffness, passive energy, and normalized energy were investigated in 36 participants during passive knee extension on an isokinetic dynamometer. Stiffness and energy values were normalized by the muscle cross-sectional area and their passive mode assured by monitoring the EMG activity. Results EFA revealed two major factors that explained 89.68% of the total variance: 53.13% was explained by the variables torqueMAX, passive stiffness, normalized stiffness, passive energy, and normalized energy, whereas the remaining 36.55% was explained by the variables ROMMAX and FSTROM. Conclusion This result supports the literature wherein two main hypotheses (mechanical and sensory theories) have been suggested to describe the adaptations of the MTU to stretching exercises. Contrary to some studies, in the present investigation torqueMAX was significantly correlated with the variables of the mechanical theory rather than those of the sensory theory. Therefore, a new approach was proposed to explain the behavior of the torqueMAX during stretching exercises.