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Author: search.filters.author.Gizzi, LeonardoSubject: search.filters.subject.610

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    Variations in muscle activity and exerted torque during temporary blood flow restriction in healthy individuals
    (2021) Gizzi, Leonardo; Yavuz, Utku Ş.; Hillerkuss, Dominic; Geri, Tommaso; Gneiting, Elena; Domeier, Franziska; Schmitt, Syn; Röhrle, Oliver
    Recent studies suggest that transitory blood flow restriction (BFR) may improve the outcomes of training from anatomical (hypertrophy) and neural control perspectives. Whilst the chronic consequences of BFR on local metabolism and tissue adaptation have been extensively investigated, its acute effects on motor control are not yet fully understood. In this study, we compared the neuromechanical effects of continuous BFR against non-restricted circulation (atmospheric pressure-AP), during isometric elbow flexions. BFR was achieved applying external pressure either between systolic and diastolic (lower pressure-LP) or 1.3 times the systolic pressure (higher pressure-HP). Three levels of torque (15, 30, and 50% of the maximal voluntary contraction-MVC) were combined with the three levels of pressure for a total of 9 (randomized) test cases. Each condition was repeated 3 times. The protocol was administered to 12 healthy young adults. Neuromechanical measurements (torque and high-density electromyography-HDEMG) and reported discomfort were used to investigate the response of the central nervous system to BFR. The investigated variables were: root mean square (RMS), and area under the curve in the frequency domain-for the torque, and average RMS, median frequency and average muscle fibres conduction velocity-for the EMG. The discomfort caused by BFR was exacerbated by the level of torque and accumulated over time. The torque RMS value did not change across conditions and repetitions. Its spectral content, however, revealed a decrease in power at the tremor band (alpha-band, 5-15 Hz) which was enhanced by the level of pressure and the repetition number. The EMG amplitude showed no differences whilst the median frequency and the conduction velocity decreased over time and across trials, but only for the highest levels of torque and pressure. Taken together, our results show strong yet transitory effects of BFR that are compatible with a motor neuron pool inhibition caused by increased activity of type III and IV afferences, and a decreased activity of spindle afferents. We speculate that a compensation of the central drive may be necessary to maintain the mechanical output unchanged, despite disturbances in the afferent volley to the motor neuron pool.
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    Editorial - somatosensory integration in human movement : perspectives for neuromechanics, modelling and rehabilitation
    (2021) Gizzi, Leonardo; Vujaklija, Ivan; Sartori, Massimo; Röhrle, Oliver; Severini, Giacomo
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    Longitudinal and transverse muscle stiffness change differently with knee osteoarthritis and do not align with stiffness sensation
    (2025) Dieterich, Angela V.; Skerl, Katrin; Paskali, Filip; Gizzi, Leonardo; Azan, Mehrin; Carvalho, Gabriela F.; Kohl, Matthias; Haueise, Andreas
    Knee osteoarthritis (OA) is a prevalent joint condition associated with disability, pain, and stiffness in the muscles surrounding the knee. Myofascial and massage techniques are employed to alleviate these symptoms. Unclear is whether muscle stiffness is measurably increased in the painful muscles, and how measured muscle stiffness relates to perceived stiffness, pain, and functional impairment. Given muscle anisotropy, stiffness changes may occur in the longitudinal plane parallel to muscle fibers or perpendicularly in the transverse plane. Shear wave velocity (SWV) was measured in both scanning planes in 21 individuals with diagnosed knee OA, 21 sex- and age-matched controls, and 20 young controls , focusing on the gastrocnemius medialis and vastus lateralis muscles under four conditions: (a) resting state, (b) holding the shank against gravity, (c) double-leg stance, and (d) single-leg stance. Median stiffness measures, the ratio of longitudinal-to-transverse stiffness, and the ratio of single-leg stance-to-baseline stiffness were compared between groups using the Kruskal- Wallis and Pairwise Asymptotic Wilcoxon rank sum tests. Correlations with the Knee Injury and Osteoarthritis Outcome Score and the Tampa Scale of Kinesiophobia were examined. Longitudinal stiffness of the gastrocnemius medialis muscle was significantly lower in the OA group at double-leg (P = 0.033) and single-leg stance (P = 0.019), with tendencies toward lower median stiffness in both muscles across most tasks. Transverse stiffness of the vastus lateralis muscle was significantly higher in the OA group at baseline (P = 0.027), with tendencies toward higher median stiffness in both muscles across most tasks. Significant moderate to excellent correlations support the clinical relevance of both longitudinal and transverse stiffness measurements. Measured and perceived stiffness were not correlated. Study results suggest that knee OA may differentially affect muscle stiffness in the longitudinal and transverse planes and that transverse stiffness measures may have clinical relevance.