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  • Author: Rubens A. da Silva x
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Edgar R. Vieira, Ruth Tappen, Sareen S. Gropper, Maria T. Severi, Gabriella Engstrom, Marcio R. de Oliveira, Alexandre C. Barbosa and Rubens A. da Silva

The objective of this pilot study was to evaluate a 6-month exercise program completed by 10 older Caribbean Americans. Assessments were done at baseline and 3 and 6 months, and included walks on an instrumented mat at preferred speed, and during street crossing simulations with regular (10 s) and reduced time (5 s). There were no significant differences on preferred walking speed over time. Differences between the street crossing conditions were found only at 6 months. Significant changes over time among the assessments were found only during street crossing with reduced time. Street crossing with reduced time was the only walking condition sensitive to capture changes associated with participating in the exercise program. There was a significant increase in dorsiflexion strength overtime. At 6 months it was significantly higher than at baseline and 3 months. The program was feasible, acceptable, and had some positive effects on walking, knee flexion, and dorsiflexion strength.

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Leonardo Shigaki, Cynthia Gobbi Alves Araújo, Mariane Guizeline Calderon, Thais Karoline Cezar Costa, Andreo Fernando Aguiar, Leonardo Oliveira Pena Costa and Rubens A. da Silva

Context: Strength/resistance training volume has historically been supported in the American College of Sports Medicine recommendations. However, for the back muscles, exercise prescription related to the number of sets, such as single versus multiple, is not well established in the literature. Objective: The purpose of this study was to compare the effects of 2 training volumes on strength and endurance of back-extensor muscles in untrained young participants with regard to a repeated-measures design. Design: Randomized controlled trial. Setting: Laboratory of functional evaluation and human motor performance. Participants: Forty-four untrained young participants (mean age = 21 y) were randomized into single-set (n = 14), multiple-set (MSG, n = 15), and untrained control (n = 15) groups. Intervention: The single-set group and MSG underwent a 10-week progressive resistance training program (2 d/wk) using a 45° Roman chair. Main Outcome Measures: Back maximal strength (dynamometer) and isometric and dynamic endurance (time limit, trunk extension–flexion cycles, and electromyography muscle fatigue estimates). Results: The results showed differences between the MSG and control group for isometric endurance time (mean = 19.8 s; 95% confidence interval, −44.1 to 4.8), but without time intervention significance. Significant improvement after training (P < .05) was found predominantly during dynamic endurance (number of repetitions) for both the MSG (+61%) and single-set group (+26%) compared with preintervention, whereas the control group reported no benefit. There was no significant (P > .05) difference in either strength or electromyography estimates after training. Conclusions: Both multiple and single volume training were efficient in promoting better back endurance during dynamic performance based on mechanical variables (time and number of repetitions).

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Rodolfo B. Parreira, Marcela C. Boer, Lucas Rabello, Viviane de Souza P. Costa, Eros de Oliveira Jr. and Rubens A. da Silva

The aim of this study was to evaluate the changes in center of pressure (COP) movement in four time intervals (5, 10, 15 and 30 s) during a one-leg stance test performed by young and elderly adults. Twelve young adults (mean 20 years) and 12 elderly subjects (mean 68 years) participated in this study. The subjects performed three 30 s trials of an eyes open one-leg stance test on a force platform, in which the COP parameter was computed at four points in time from same original COP signal. Significant differences were found between the young and elderly adults (P < .007) only at the 10, 15 and 30 s intervals. For both groups, COP changes were significantly different between the 5 s time interval and other intervals (10, 15 and 30 s). In conclusion, these results pointed out that age-related difference in COP changes were time dependent. This suggests that the use of longer durations increases the possibility of distinguishing more subtle differences in postural strategy among different groups of subjects.