We investigated the relationship between impedance parameters and skeletal muscle function in the lower extremities, as well as the effectiveness of impedance parameters in evaluating muscle quality. Lower extremity impedance of 19 healthy men (aged 23–31 years) measured using the direct segmental multi-frequency bioelectrical impedance analysis were arc-optimized using the Cole–Cole model, following which phase angle (PA), $${R}_{i}/{R}_{e}$$ R i / R e , and β were estimated. Skeletal muscle function was assessed by muscle thickness, muscle intensity, and isometric knee extension force (IKEF). IKEF was positively correlated with PA (r = 0.58, p < 0.01) and β (r = 0.34, p < 0.05) was negatively correlated with $${R}_{i}/{R}_{e}$$ R i / R e (r = − 0.43, p < 0.01). Stepwise multiple regression analysis results revealed that PA, β, and $${R}_{i}/{R}_{e}$$ R i / R e were correlated with IKEF independently of muscle thickness. This study suggests that arc-optimized impedance parameters are effective for evaluating muscle quality and prediction of muscle strength.

The suggested target associated with maintaining IADL in patients with hip OA is the cut-off value of 42.3 m/min for 10 mWS found in this study.

Verification of the accuracy of measuring the muscle cross-sectional area and muscle intensity of the rectus femoris using ultrasonography. Jpn J Compr Rehabil Sci 2018; 9: 66-72.Objective: This study aimed to establish ultrasonography as a method of measuring the muscle cross-sectional area and muscle intensity of the rectus femoris and to assess its measurement accuracy. Methods: Three testers measured the muscle crosssectional area and muscle intensity of the rectus femoris using ultrasonography in 16 healthy male volunteers. Intra-rater and inter-rater reliabilities were evaluated using the intraclass correlation coefficient (ICC), and Bland-Altman (B-A) analysis was used to confirm the systematic error and measure the minimum detectable change. Results: Intra-tester and inter-tester ICCs of the muscle cross-sectional area and muscle intensity were ≥0.9 and ≥0.7, respectively. On B-A analysis, no systematic error was observed in each measurement. The minimum testable changes were 0.39 cm 2 for the intra-tester cross-sectional area, 0.15 cm 2 for the intertester cross-sectional area, 6.77 for the intra-tester intensity, and 4.47 for the inter-tester intensity. Conclusion:The muscle cross-sectional area and muscle intensity of the rectus femoris can be measured with high accuracy using this measurement method. In addition, changes larger than the minimum detectable change can be used as a true change in clinical efficacy assessments.

Electromyography (EMG) and mechanomyography (MMG) have been used to directly evaluate muscle function through the electromechanical aspect of muscle contraction. The purpose of this study was to establish new absolute indices to describe muscle contraction performance during dynamic exercise by combining EMG and displacement MMG (dMMG) measured simultaneously using our previously developed MMG/EMG hybrid transducer system. Study participants were eight healthy male non-athletes (controls) and eight male athletes. EMG and dMMG of the vastus medialis were measured for 30 s during four cycles of recumbent bicycle pedaling (30, 60, 90, and 120 W) and on passive joint movement. Total powers were calculated based on the time domain waveforms of both signals. Muscle contraction performance was verified with the slope of regression line (SRL) and the residual sum of squares (RSS) obtained from EMG and dMMG correlation. EMG and dMMG has increased with the work rate. Force and EMG were similar between groups, but dMMG showed a significant difference with load increase. Athletes had significantly higher SRL and significantly lower RSS than controls. The average value divided by SRL and RSS was higher in athletes than in controls. The indices presented by the combined approach of EMG and dMMG showed a clear contrast between the investigated groups and may be parameters that reflect muscle contraction performance during dynamic exercise.

Electromyography (EMG) and mechanomyography (MMG) have been used to directly evaluate muscle function through the electromechanical aspect of muscle contraction. The purpose of this study was to establish new absolute indices to describe muscle contraction performance during dynamic exercise by combining EMG and displacement MMG (dMMG) measured simultaneously using our previously developed MMG/EMG hybrid transducer system. Study participants were eight healthy male non-athletes (controls) and eight male athletes. EMG and dMMG of the vastus medialis were measured for 30 s during four cycles of recumbent bicycle pedaling (30, 60, 90, and 120 W) and on passive joint movement. Total powers were calculated based on the time domain waveforms of both signals. Muscle contraction performance was verified with the slope of regression line (SRL) and the residual sum of squares (RSS) obtained from EMG and dMMG correlation. EMG and dMMG has increased with the work rate. Force and EMG were similar between groups, but dMMG showed a significant difference with load increase. Athletes had significantly higher SRL and significantly lower RSS than controls. The average value divided by SRL and RSS was higher in athletes than in controls. The indices presented by the combined approach of EMG and dMMG showed a clear contrast between the investigated groups and may be parameters that reflect muscle contraction performance during dynamic exercise.