Percorrer por autor "Neto, Tiago"
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- Hamstring stiffness pattern during contraction in healthy individuals: analysis by ultrasound-based shear wave elastographyPublication . Mendes, Bruno; Firmino, Telmo; Oliveira, Raúl; Neto, Tiago; Infante, Jorge; Vaz, João R; Freitas, SandroPurpose To assess the stiffness of hamstring muscles during isometric contractions in healthy individuals, using ultrasoundbased shear wave elastography to (1) determine the intra- and inter-day assessment repeatability, (2) characterize the stiffness of semitendinosus (ST) and biceps femoris long head (BFlh) along the contraction intensity, and (3) characterize stiffness distribution among the hamstring muscles and inter-limb symmetry. Methods Two experiments were conducted. In experiment I (n = 12), the intra-day repeatability in assessing the BFlh and ST stiffness were determined at intensities between 10–60% of maximal voluntary isometric contraction (MVIC) in a single session. In experiment II (n = 11), the stiffness of the hamstring muscles of both thighs was assessed at 20% of MVIC in the first session; and retested (for one randomly chosen thigh) in a second session. Isometric contraction of knee flexors was performed with the knee flexed at 30° and with the hip in a neutral position. Results Moderate-to-very-high intra- and inter-day repeatability was found (ICC = 0.69–0.93). The BFlh/ST stiffness ratio increased with contraction intensity. At 20% of MVIC, the ST showed the highest stiffness among the hamstring muscles (p < 0.02), with no differences between the remaining hamstring muscles (p > 0.474). No differences were found between limbs (p = 0.12). Conclusions The stiffness distribution among the hamstring muscles during submaximal isometric contractions is heterogeneous, but symmetric between limbs, and changes depending on the contraction intensity. Shear wave elastography is a reliable tool to assess the stiffness of hamstring muscles during contraction.
- Noninvasive measurement of sciatic nerve stiffness in patients with chronic low back related leg pain using shear wave elastographyPublication . Neto, Tiago; Freitas, Sandro; Andrade, Ricardo; Vaz, João R; Mendes, Bruno; Firmino, Telmo; Bruno, Paula; Nordez, Antoine; Oliveira, RaúlObjectives—The purpose of this study was to determine whether sciatic nerve stiffness is altered in people with chronic low back–related leg pain by using shear wave elastography. Methods—In this cross-sectional study, the sciatic nerve shear wave velocity (ie, an index of stiffness) was measured in both legs of 16 participants (8 with unilateral low back–related leg pain and 8 healthy controls). Sciatic stiffness was measured during a passive ankle dorsiflexion motion performed at 28/s in an isokinetic dynamometer. The ankle range of motion and passive torque, as well as muscle activity, were also measured. Results—In people with low back–related leg pain, the affected limb showed higher sciatic nerve stiffness compared to the unaffected limb (111.3%; P5.05). However, no differences were observed between the unaffected limb of people with low back–related leg pain and the healthy controls (P5.34). Conclusions—People with chronic low back–related leg pain have interlimb differences in sciatic nerve stiffness, as measured by a safe and noninvasive method: shear wave elastography. The changes found may be related to alterations in nerve mechanical properties, which should be confirmed by future investigations.