Osmar Pinto Neto

Publications (2)4.29 Total impact

• Article: Hand dominance during constant force isometric contractions: evidence of different cortical drive commands.

  Rafael Pereira, Ivna Vidal Freire, Cláudia Virgínia Galindo Cavalcanti, Carla Patrícia Novais Luz, Osmar Pinto Neto
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  ABSTRACT: The purpose of this study was to investigate force variability and sensoriomotor strategies of dominant and nondominant hands of right and left-handed subjects during a submaximal isometric force production task. Twelve right-handed adults (9 men and 3 women; 23 ± 3 year) and twelve left-handed adults (4 men and 8 women; 24 ± 3 year) performed an isometric constant force contraction sustained at 30 and 50% of maximal force for 10 s. Surface EMG signals were obtained from forearm flexors and extensors. Force signals were analyzed in the time (CV of force) and frequency (0-10 Hz) domain. The neural activation of the involved muscles was investigated from the EMG structure using the cross-wavelet spectra of the interference EMG signals of six different frequency bands of the EMG signals were quantified (5-13, 13-30, 30-60, 60-100, 100-150 and 150-200 Hz). The major findings were: (1) dominant and nondominant hands of right- and left-handed subjects exhibited similar CV of force; (2) the power spectrum of force is influenced by handedness, with greater 1-3 Hz oscillations for left-handed subjects when compared to right-handed subjects; (3) right-handed subjects have greater 30-60 Hz neuromuscular activation when compared to left-handed subjects. Our results indicate that right-handed individuals may rely preferentially in visual feedback to carry out a task with visual and proprioceptive feedback because of the left hemisphere specialization on the visuomotor control.
  Arbeitsphysiologie 12/2011; 112(8):2999-3006. · 2.15 Impact Factor
• Article: Task failure during standing heel raises is associated with increased power from 13 to 50 Hz in the activation of triceps surae.

  Rafael Pereira, Ludmila Schettino, Marco Machado, Pierre Augusto Victor da Silva, Osmar Pinto Neto
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  ABSTRACT: The goal of this paper was to investigate the amplitude and sub-100 Hz frequency content of surface electromyography (EMG) signals obtained from agonist, antagonist and synergist muscles during a heel-raise task sustained to failure. Twenty-two healthy adults, 14 men and 8 women participated in the study. Surface EMG data from the raising and lowering phases of the movement were studied in the time (EMG amplitude) and frequency (wavelet transform) domains. For the raising phase, we found a significant increase in the EMG amplitude of all muscles studied throughout the task (P < 0.02); however, for the lowering phase, we found a decrease in overall muscle activation for the medial gastrocnemius and tibialis anterior. Additionally, we found higher 13-30 and 30-50 Hz normalized power during the raising phase for the triceps surae prior to task failure and at task failure compared with the beginning and midway of the task (P < 0.05); during the lowering phase, however, we found higher normalized power from 30 to 50 Hz for the triceps surae (P < 0.01) and higher 13-30 Hz normalized power for the tibialis anterior (P < 0.01) at task failure compared with the beginning and midway of the task. Finally, we showed that a dynamic task performed until failure can induce different activation strategies for agonist, antagonist and synergist muscles, and that the frequency content below 100 Hz contains useful information about the neural activation of these muscles in relation to task failure that is not evident from the EMG amplitude.
  Arbeitsphysiologie 05/2010; 110(2):255-65. · 2.15 Impact Factor