Fratini, A. | bioRxiv Science

bioRxiv2021

Dynamic analysis of lower leg muscles response to whole body vibration stimulation at different frequencies and postures: implications for training

PurposeTo characterise the mechanical and neuromuscular response of lower limb muscles in subjects undergoing Whole Body Vibration (WBV) at different frequencies while holding two static postures. MethodsTwenty-five participants underwent WBV at 15, 20, 25 and 30 Hz while holding a static hack squat and on fore feet posture. Surface electromyography (sEMG) and soft tissue accelerations were collected from Gastrocnemius Lateralis (GL), Soleus (SOL) and Tibialis Anterior (TA) muscles. ResultsOnly specific WBV settings led to a significant increase in muscle contraction. Specifically, the WBV-induced activation of SOL and GL was maximal in fore-feet and in response to higher frequencies. Estimated displacement at muscle bellies revealed a resonant pattern never highlighted before. After stimulation starts, muscle oscillation reaches a peak followed by a drop and a further stabilisation (few seconds after the peak) that suggests the occurrence of a neuromuscular activation to reduce the vibration-induced oscillation. ConclusionLower leg muscles need a response time to tune to a vibratory stimulation, which discourages the use of dynamic exercises on vibrating platforms. To maximize calf muscle response to WBVs, a stimulation frequency in the range of 25-30 Hz and an on fore feet posture are recommended.

physiology↗

bioRxiv2020

Performance assessment of Respiratory Viral ELITe MGB(R) assay for the quantitative detection of influenza A/B and respiratory syncytial viruses

Influenza (Flu) and respiratory syncytial virus (RSV) are responsible for lower respiratory tract infections (LRTIs) associated with significant hospitalization among young children. In the present study, the performances of a triplex PCR assay detecting Flu A/B and RSV were compared with our in-house single-plex assays using 160 stored respiratory specimens previously tested using a panel of laboratory-developed real-time RT-PCR. Of them, 61 were positive for FluA, 41 for FluB, and 58 for RSV. All samples were retrospectively quantified with Respiratory Viral (RV) ELITe MGB(R) Panel (ELITechGroup Molecular Diagnostics, Puteaux, France) processed using ELITe InGenius(R) system. Overall, the total percentage agreement observed was 93.4% (57/61) for FluA, 92.7% (38/41) for FluB, and 86.2% (50/58) for RSV. A significant correlation of VL values was observed between the two methods for FluA and RSV ({rho}= 0.91 and 0.84). This finding was supported by the strength of agreement between the two methods, as showed by the linear regression analysis (R2 =0.84 and 0.80). FluB viral load values measured by RV Panel were less significantly correlated ({rho}= 0.77 and R2 =0.56). The bland-Altman analysis showed how 84.2% (48/57) of FluA and 86.0% of RSV (43/50) samples fell within {+/-}1.0 Log10 variation from our laboratory results, while only 21.1% (8/38) of FluB results fell within this range. The great majority of FluB samples (29/30) outside range had values higher than +1.0 Log10 (median +2.1 Log10 range +1.0 to +3.5 Log10). In conclusion, RV ELITe MGB(R) Panel constitutes a valid and robust system for simultaneous detection and quantification of Flu A/B and RSV.

microbiology↗