Study on Respiratory Rate Monitoring Method Based on Breath Sounds / 中国医疗器械杂志

The article aims to discuss the feasibility of using respiratory sounds to monitor respiratory rate. The average power of respiratory sounds was created firstly, the autocorrelation algorithm was used to calculate the respiratory cycle. The respiratory cycle of nasal flow pressure signal was calculated simultaneously, and the result was taken as a reference standard, then, two groups of respiratory cycle data were analyzed by correlation analysis and Bland-Altman analysis. The respiratory rate is relatively stable, using respiratory sounds monitor respiratory rate is feasible, the respiratory rate changes obviously, the existing methods and algorithm using respiratory sounds are temporarily unable to accurately reflect the changes of respiratory rate, further research is needed.

Effect of teeth clenching on force-velocity relationships in isokinetic knee extension / 体力科学

To investigate the effect of teeth clenching on isokinetic knee extension at various velocities, isokinetic muscle strength during knee extension was measured in association with teeth clenching at 30, 60, 150, 300 and 450 degrees per second (deg/s) using the Cybex 6000 isokinetic dynamometer. The volunteer subjects were 9 healthy males (26.2±0.97 years) . The peak torque per body weight and average power per body weight were statistically analyzed. Our results demonstrated that the peak torque per body weight with teeth clenching at 30, 60 and 150 deg/s significantly increased by 7.0%, 7.4% and 4.9%, respectively (p<0.05), but no significant differences were found at 300 and 450 deg/s. While the average power per body weight with teeth clenching at 30, 60 and 150 deg/s significantly increased by 6.5%, 6.1% and 6.9%, respectively (p<0.05), no sig-nificant differences were found at 300 and 450 deg/s. A significant negative correlation was shown between the isokinetic angular velocity and the difference in peak torque per body weight derived from with and without teeth clenching (r=-0.699; p<0.05) . These findings suggested that the effect of teeth clenching on isokinetic muscle strength of knee extension was dependent on the angular velocity, and at lower angular velocities teeth clenching had the effect of increasing the isokinetic muscle strength during knee extension.

A Comparative Study of Eccentric and Concentric Isokinetic Exercise Testing

The understandings of the characteristics of eccentric exercise are very important because all sports and daily activities under the gravity force should be well coupled between concentric contraction and eccentric contraction as accelerator and decelerator respectively. We tested 40 knee flexors and extensors of 20 normal young persons at different anglular velocities of 60o/sec and 120o/sec using Cybex 6000 (A division of Lumax, New York) isokinetic dynamometer in order to know the characteristics of eccentric isokinetic contraction parameters by comparing with concentric isokinetic parameters. Compared to the concentric isokinetic contraction, eccentric isokinetic the peak torque and average power values of knee extensor and flexor muscles showed negative values which means that eccentric contractions were coupled with concentric contractions as decelerator and energy absorptioner. The peak torque values of eccentric contraction were 38 - 61%, 44 - 79% higher in flexor and extensor, respectively than those of concentric contraction and not so decreased as the peak torque of concentric contraction decreased in high angular velocity. The average power values of knee flexor and extensor muscles were definitely low in eccentric contracton than those of concentric contraction but were increased simultaneously with high angular velocity contraction. Further studies about the velocity dependency, muscle soreness, methodology to measure real eccentric activities and other parameters of eccentric contraction are needed imminently.