Navegando por Palavras-chave "cross-sectional area"

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    Effects of Strength and Power Training on Neuromuscular Variables in Older Adults
    (Human Kinetics Publ Inc, 2012-04-01) Wallerstein, Lilian França; Tricoli, Valmor; Barroso, Renato; Rodacki, Andre L. F.; Russo, Luciano; Aihara, André Yui [UNIFESP]; Fernandes, Artur da Rocha Correa [UNIFESP]; Mello, Marco Tulio de [UNIFESP]; Ugrinowitsch, Carlos; Universidade de São Paulo (USP); Univ Fed Parana; Universidade Federal de São Paulo (UNIFESP)
    The purpose of this study was to compare the neuromuscular adaptations produced by strength-training (ST) and power-training (PT) regimens in older individuals. Participants were balanced by quadriceps cross-sectional area (CSA) and leg-press 1-repetition maximum and randomly assigned to an ST group (n = 14; 63.6 +/- 4.0 yr, 79.7 +/- 17.2 kg, and 163.9 +/- 9.8 cm), a PT group (n = 16; 64.9 +/- 3.9 yr. 63.9 +/- 11.9 kg, and 157.4 +/- 7.7 cm), or a control group (n = 13; 63.0 +/- 4.0 yr, 67.2 +/- 10.8 kg, and 159.8 +/- 6.8 cm). ST and PT were equally effective in increasing (a) maximum dynamic and isometric strength (p < .05), (b) increasing quadriceps muscle CSA (p < .05), and (c) decreasing electrical mechanical delay of the vastus lateralis muscle (p < .05). There were no significant changes in neuromuscular activation after training. The novel finding of the current study is that PT seems to be an attractive alternative to regular ST to maintain and improve muscle mass.
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    Multivariate Analysis in the Maximum Strength Performance
    (Georg Thieme Verlag Kg, 2012-12-01) Souza, E. O. de; Tricoli, V.; Paulo, A. C.; Silva-Batista, C.; Cardoso, R. K.; Brum, P. C.; Bacurau, A. V. N.; Laurentino, G.; Neves-, M.; Aihara, A. Y. [UNIFESP]; Ugrinowitsch, C.; Universidade de São Paulo (USP); Univ Paulista UNIP; Univ Nove Julho; Universidade Federal de São Paulo (UNIFESP)
    This study performed an exploratory analysis of the anthropometrical and morphological muscle variables related to the one-repetition maximum (1RM) performance. in addition, the capacity of these variables to predict the force production was analyzed. 50 active males were submitted to the experimental procedures: vastus lateralis muscle biopsy, quadriceps magnetic resonance imaging, body mass assessment and 1RM test in the leg-press exercise. K-means cluster analysis was performed after obtaining the body mass, sum of the left and right quadriceps muscle cross-sectional area (Sigma CSA), percentage of the type II fibers and the 1RM performance. the number of clusters was defined a priori and then were labeled as high strength performance (HSP1RM) group and low strength performance (LSP1RM) group. Stepwise multiple regressions were performed by means of body mass, Sigma CSA, percentage of the type II fibers and clusters as predictors' variables and 1RM performance as response variable. the clusters mean +/- SD were: 292.8 +/- 52.1 kg, 84.7 +/- 17.9 kg, 19249.7 +/- 1645.5 mm(2) and 50.8 +/- 7.2% for the HSP1RM and 254.0 +/- 51.1 kg, 69.2 +/- 8.1 kg, 15483.1 +/- 1 104.8 mm(2) and 51.7 +/- 6.2 %, for the LSP1RM in the 1RM, body mass, Sigma CSA and muscle fiber type II percentage, respectively. the most important variable in the clusters division was the Sigma CSA. in addition, the Sigma CSA and muscle fiber type II percentage explained the variance in the 1RM performance (Adj R-2 = 0.35, p = 0.0001) for all participants and for the LSP1RM (Adj R-2 = 0.25, p = 0.002). for the HSP1RM, only the Sigma CSA was entered in the model and showed the highest capacity to explain the variance in the 1RM performance (Adj R-2 = 0.38, p = 0.01). As a conclusion, the muscle CSA was the most relevant variable to predict force production in individuals with no strength training background.
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    Paradoxical sleep deprivation induces muscle atrophy
    (Wiley-Blackwell, 2012-03-01) Dattilo, Murilo [UNIFESP]; Antunes, Hanna Karen Moreira [UNIFESP]; Medeiros, Alessandra [UNIFESP]; Mônico-Neto, Marcos [UNIFESP]; Souza, Helton de Sá; Lee, Kil Sun [UNIFESP]; Tufik, Sergio [UNIFESP]; Mello, Marco Tulio de [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); CEPE
    Introduction: Because paradoxical sleep deprivation (PSD) induces a catabolic hormone profile, we sought to evaluate the morphology of the tibialis anterior (TA) muscle and testosterone and corticosterone levels of paradoxical sleepdeprived rats.Methods: Three study groups of rats were established: the first group was sleep deprived for 96 h; the second group was also sleep deprived for 96 h, but then returned to their home-cage and allowed to sleep for the next 96 h; and the third group was the control group, with a normal sleep cycle. Results: PSD reduced the weight and fiber cross-sectional area of the TA muscle. Moreover, PSD enhanced plasma corticosterone and reduced serum testosterone levels. the 96 h of sleep after PSD was sufficient to restore partially the morphology of TA, while hormones returned to basal levels. Conclusion: PSD induces hormonal alterations that may mediate muscle atrophy. Muscle Nerve, 2012