Skeletal Muscle Function in Young Patients With Cystic Fibrosis.

PURPOSE: Defects in the gene encoding the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) cause CF. Absence of the CFTR may result in skeletal muscle dysfunction. Here, we tested skeletal muscle function in male adolescent patients with CF. METHODS: Ten CF and 10 control participants (age: 16.8 ± 0.6 years) performed 7 repetitive sets of maximum voluntary contractions (MVCs) and underwent an isometric fatigue test of the knee extensors. Electromyography (EMG) activity was recorded from the m. vastus lateralis (VL) and m. vastus medialis (VM). RESULTS: In CF, the MVC torque was lower and correlated with the predicted forced expiratory volume in one second (r = .73, p = .012, n = 10). The M-wave in the VL was shorter in CF than in controls (18.6 ± 0.5 vs. 20.3 ± 0.5 ms, p < .028). In the VM, both the M-wave (4.96 ± 0.61 vs. 7.97 ± 0.60 mV, p = .001) and the EMG (0.29 ± 0.04 vs. 0.47 ± 0.04 mV, p = .004) amplitudes were smaller in CF. CONCLUSION: The differences in the VL and VM EMG signals between the groups indicate that the lower MVC torque in CF did not result from the direct impact of a CFTR defect on the sarcolemmal excitability; the differences more likely resulted from the less developed musculature in the patients with CF.

Functional quality assessment of whole-body vibration training devices based on instantaneous amplitude and frequency of photogrammetric vibration measurements.

The practical use of whole-body vibration training (WBVT) and such research may be negatively influenced by generated vibrations with amplitudes, frequencies, and/or patterns that deviate from preset adjustments on WBVT devices. This study examined whether prolonged regular use can generate respective deviations. Four WBVT devices, used for 19 months in a research project on the effects of WBVT, were analyzed using photogrammetry before start of the research project and after 19 months. Divergences between preset and measured amplitudes and frequencies were calculated for all measurements. To quantify how well the output of devices correlates with the target setting, the vibration characteristics were calculated. In particular, exact long-term measurements related to the vibration amplitude is conducted and analyzed for the first time, which has been found as an important measure of the device functional quality. One device had a significantly (p<0.01) larger machine run time than the other three. This one showed the most pronounced signs of functional impairments concerning instantaneous amplitudes, frequencies and the mode of vibration after prolonged use. These results based on photometric measurements underline again that prolonged use can result in divergences between preset and actual applied amplitudes, frequencies, mode of vibration and other accuracy measurement metrics.

Sinus-like versus random vibration: Acute effects on elderly people with a high risk of falling.

BACKGROUND: Whole-body vibration (WBV) could be an alternative training method for elderly with a high risk of falling. RESEARCH QUESTION: What acute effects of sinus-like and random WBV intervention occur in this risk group and how do they differ? METHODS: This prospective pilot study was performed on two days separated by a one-week wash-out phase. Twelve subjects (10 women and 2 men, age 77.7 ± 5.3; 162.3 ± 7.4 cm; 82.4 ± 15.2 kg; BMI 31.2 ± 5.1 kg/m²) undertook sinus-like WBV intervention. One week later random WBV were performed. This consisted of six intervals each lasting 60 s, with heart and respiratory rates monitored. Feasibility outcomes involved safety and compliance. The primary endpoint was postural control, measured by a static posturography before and after the first interval and complete intervention. Secondary outcomes measured before and after the intervention were a Timed-Up-and-Go-Test (TUGT) and an instrumental gait analysis. RESULTS: Random WBV intervention showed positive acute effect on postural control (Standard deviation (SD) Ellipse area p = 0.007; SD of the Center of force (CoF) independent from direction p = 0.017; SD of the CoF in the antero-posterior direction p = 0.011). There were no significant acute effects on TUGT or gait analysis (comparison between sinus-like and random WBV: Single Task: ΔVelocity p = 0.373, ΔStep time p = 0.077, ΔStep length p = 0.369, ΔStride length p = 0.408, ΔDouble-support-time p = 0.492; Dual task: ΔVelocity p = 0.580, ΔStep-time p = 0.559, ΔStep length p = 0.626, ΔStride length p = 0.584, ΔDouble-support-time p = 0.550). During sinus-like WBV, heart rate increased significantly from rest 69.7 ± 20.9bpm to max.146.0 ± 24.9bpm (p = 0.025). Respiratory rate increased significantly from 10.0 ± 1.0 to max.32.0 ± 6.0 (p = 0.011) during random WBV. No undesirable side effects were observed. SIGNIFICANCE: Findings demonstrate that random WBV improves acute functional ability of postural control, but not gait for elderly people with a high risk of falling. Intervention with WBV seems safe and well accepted by participants. Monitoring of heart and respiratory rate offers protection for subjects with heart disease.

Deviations in frequency and mode of vibration in whole-body vibration training devices with long-term and regular use.

Research regarding whole body vibration training (WBVT) and its practical use may be hindered by the fact that WBVT devices generate frequencies and/or modes of vibration different from their preset adjustments. This research aimed to clarify whether prolonged regular use can generate such deviations in frequency and mode of vibration. Three WBVT devices, each used for approximately 13 months in two research projects, were tested with an accelerometer before start of the 1st study, after four months, and after 13 months (the completion of the 2nd study). Divergences between the preset and measured frequencies were calculated for all measurements. Furthermore, the total harmonic distortion (THD), an index for signal deviations from a perfect sine wave, and the sum signal-to-modulation-noise-ratio (SMNR), an indicator of fidelity, were recorded. One device had a significantly larger machine run time than the other two, and it displayed the most pronounced signs of impaired function concerning frequency, mode of vibration, and random variability (SMNR) after prolonged use. These results indicate that prolonged use will result in divergences between the preset and actual applied frequencies as well as in the mode of vibration and other accuracy measurements.