Aging Effects on Neuromuscular Activity in Karate Practitioners

Aging leads to a general decline in body functions that affects quality of life. Sports practice is recommended as a means to attenuate the impact of the aging process. The aim of this study was to identify and analyze the neuromuscular activity and its patterns on active karate practitioners and assess the effects of the aging process. Two groups of black belt male karate practitioners, one with nine practitioners over 50 years old and the other with 21 practitioners aged between 20-30 years old performed the frontal kick mae-geri. Kinematic and electromyographic data of five muscles were collected from the right leg. Results showed two distinct periods of muscular activation in the mae-geri performance, with similar muscles activity patterns between groups. Nevertheless, some differences were found in the muscles＇ activity onset and offset, in root mean square and in inter-muscle delay and co-contraction periods. Those differences indicated that aging affects the neuromuscular activity in the mae-geri performance of the oldest karate practitioners. Nevertheless, the results showed that lifelong practice of karate can preserve the quality of the neuromuscular activity in older practitioners when they perform a kick, and this could be associated with benefits to balance control.

Evaluation of neuromuscular activity in patients with obstructive sleep apnea using chin surface electromyography of polysomnography

Background It is believed that defects in upper airway neuromuscular control play a role in sleep apnea pathogenesis. Currently, there is no simple and non-invasive method for evaluating neuromuscular activity for the purpose of screening in patients with obstructive sleep apnea. This study was designed to assess the validity of chin surface electromyography of routine polysomnography in evaluating the neuromuscular activity of obstructive sleep apnea subjects and probe the neuromuscular contribution in the pathogenesis of the condition. Methods The chin surface electromyography of routine polysomnography during normal breathing and obstructive apnea were quantified in 36 male patients with obstructive sleep apnea. The change of chin surface electromyography from normal breathing to obstructive apnea was expressed as the percent compensated electromyography value, where the percent compensated electromyography value = （normal breath surface electromyography - apnea surface electromyography）/normal breath surface electromyography, and the percent compensated electromyography values among subjects were compared. The relationship between sleep apnea related parameters and the percent compensated electromyography value was examined. Results The percent compensated electromyography value of the subjects varied from 1% to 90% and had a significant positive correlation with apnea hypopnea index （R2=0.382, P 〈0.001）. Conclusions Recording and analyzing chin surface electromyography by routine polysomnography is a valid way of screening the neuromuscular activity in patients with obstructive sleep apnea. The neuromuscular contribution is different among subjects with obstructive sleep apnea.

Role of DSC1 in Drosophila melanogaster synaptic activities in response to haedoxan A

Drosophila sodium channel 1 (DSC1) encodes a voltage-gated divalent cation channel that mediates neuronal excitability in insects. Previous research revealed that DSC1 knockout Drosophila melanogaster conferred different susceptibility to insecticides, which indicated the vital regulation role of DSC1 under insecticide stress. Haedoxan A (HA) is a lignan compound isolated from Phryma leptostachya, and we found that HA has excellent insecticidal activity and is worthy of further study as a botanical insecticide. Herein, we performed bioassay and electrophysiological experiments to test the biological and neural changes in the larval Drosophila with/without DSC1 knockout in response to HA. Bioassay results showed that knockout of DSC1 reduced the sensitivity to HA in both w1118 (a common wild-type strain in the laboratory) and parats1 (a pyrethroid-resistant strain) larvae. Except for parats1/DSC1−/−, electrophysiology results implicated that HA delayed the decay rate and increased the frequency of miniature excitatory junctional potentials of Drosophila from w1118, parats1, and DSC1−/− strains. Moreover, the neuromuscular synapse excitatory activities of parats1/DSC1−/− larvae were more sensitive to HA than DSC1−/− larvae, which further confirmed the functional contribution of DSC1 to neuronal excitability. Collectively, these results indicated that the DSC1 channel not only regulated the insecticidal activity of HA, but also maintained the stability of neural circuits through functional interaction with voltage-gated sodium channels. Therefore, our study provides useful information for elucidating the regulatory mechanism of DSC1 in the neural system of insects involving the action of HA derived from P. leptostachya.