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Purpose: Semitendinosus and gracilis muscles whose tendons are used in surgical reconstruction of the anterior cruciate ligament maintain their contractile ability, but the peak torque angle of hamstring muscles shifted to a shallow angle postoperatively. The goal was to quantify the influence of the myofascial structures on instantaneous moment arms of knee muscles to attempt explaining the above-mentioned post-surgical observations. Methods: Hamstring harvesting procedures were performed by a senior orthopaedic surgeon on seven lower limbs from fresh-frozen specimens. Femoro-tibial kinematics and tendons excursion were simultaneously recorded at each step of the surgery. Results: No significant difference was demonstrated for instantaneous moment arm of gracilis during anterior cruciate ligament surgery (84% of the maximum intact values; P ≥ 0.05). The first significant semitendinosus moment arm decrease was observed after tendon harvesting (61% of the maximum intact values; p ≤ 0.005). After hamstring harvesting, the maximum and minimum moment arm (both gracilis and semi tendinosus) shifted to a shallow angle and 90°, respectively. Conclusion: Moment arm modifications by paratenons and the loose connective tissue release are essential to understand the peak torque obtained to a shallow angle. Level of evidence: Basic science study, biomechanics., SCOPUS: ar.j, info:eu-repo/semantics/published

The functional consequences of differential muscle activation and contractile behavior between mechanically coupled synergists are still poorly understood. Even though synergistic muscles exert similar mechanical effects at the joint they span, differences in the anatomy, morphology and neural drive may lead to non-uniform contractile conditions. This study aimed to investigate the patterns of activation and contractile behavior of triceps surae muscles, to understand how these contribute to the relative displacement between the one-joint soleus (SO) and two-joint lateral gastrocnemius (LG) muscle bellies and their distal tendons during locomotion in the rat. In seven rats, muscle belly lengths and muscle activation during level and upslope trotting were measured by sonomicrometry crystals and electromyographic electrodes chronically implanted in the SO and LG. Length changes of muscle-tendon units (MTUs) and tendon fascicles were estimated based on joint kinematics and muscle belly lengths. Distances between implanted crystals were further used to assess longitudinal and transversal deformations of the intermuscular volume between the SO and LG. For both slope conditions, we observed differential timing of muscle activation as well as substantial differences in contraction speeds between muscle bellies (maximal relative speed 55.9 mm s-1). Muscle lengths and velocities did not differ significantly between level and upslope locomotion, only EMG amplitude of the LG was affected by slope. Relative displacements between SO and LG MTUs were found in both longitudinal and transversal directions, yielding an estimated maximal length change difference of 2.0 mm between their distal tendons. Such relative displacements may have implications for the force exchanged via intermuscular and intertendinous pathways.

The functional consequences of differential muscle activation and contractile behavior between mechanically coupled synergists are still poorly understood. Even though synergistic muscles exert similar mechanical effects at the joint they span, differences in the anatomy, morphology and neural drive may lead to non-uniform contractile conditions. This study aimed to investigate the patterns of activation and contractile behavior of triceps surae muscles, to understand how these contribute to the relative displacement between the one-joint soleus (SO) and two-joint lateral gastrocnemius (LG) muscle bellies and their distal tendons during locomotion in the rat. In seven rats, muscle belly lengths and muscle activation during level and upslope trotting were measured by sonomicrometry crystals and electromyographic electrodes chronically implanted in the SO and LG. Length changes of muscle-tendon units (MTUs) and tendon fascicles were estimated based on joint kinematics and muscle belly lengths. Distances between implanted crystals were further used to assess longitudinal and transversal deformations of the intermuscular volume between the SO and LG. For both slope conditions, we observed differential timing of muscle activation as well as substantial differences in contraction speeds between muscle bellies (maximal relative speed 55.9 mm s-1). Muscle lengths and velocities did not differ significantly between level and upslope locomotion, only EMG amplitude of the LG was affected by slope. Relative displacements between SO and LG MTUs were found in both longitudinal and transversal directions, yielding an estimated maximal length change difference of 2.0 mm between their distal tendons. Such relative displacements may have implications for the force exchanged via intermuscular and intertendinous pathways.

Objective: To assess the immediate effects on vertical mouth opening, orofacial mechanosensitivity, and lumbar and suboccipital mobility after adding a myofascial induction technique to a multimodal protocol in subjects with temporomandibular disorders (TMD). Design: A randomized and double-blind controlled trial was carried out. Settings/location: University-based physical therapy research clinic. Subjects: Sixty subjects (35±11.22 years) with TMD, and restricted mobility of the mandibular condyles and the first cervical vertebrae, were recruited and randomized to either a control group (CG) (n=30) or an experimental group (EG) (n=30). Interventions: The CG underwent a neuromuscular technique over the masseter muscles and passive hamstring muscle stretching. A suboccipital muscle inhibition technique was added to this protocol in the EG. Outcome measures: Primary measurements were made of vertical mouth opening and pressure pain threshold of the masseter muscles. Secondary outcome measures included pressure algometry of the trigeminal nerve, suboccipital range of motion, and lumbar spine mobility, assessed with the sit-and-reach (SAR) test and lumbar forward bending. All evaluations were collected at baseline and immediately after intervention. Results: In the intragroup comparison, the EG observed an increase in suboccipital flexion (p<0.001; F1,29=14.47; R(2)=0.33) and the SAR test (p=0.009; F1,29=7.89; R(2)=0.21). No significant differences were found in the between-group comparison for any variable (p>0.05). Conclusion: The inclusion of a myofascial induction maneuver in a protocol combining local (neuromuscular treatment) and distal techniques (hamstring stretching) in subjects with TMD has no impact on improving mouth opening, suboccipital and lumbar mobility, and orofacial sensitivity to mechanical pressure.

Objective: To assess the immediate effects on vertical mouth opening, orofacial mechanosensitivity, and lumbar and suboccipital mobility after adding a myofascial induction technique to a multimodal protocol in subjects with temporomandibular disorders (TMD). Design: A randomized and double-blind controlled trial was carried out. Settings/location: University-based physical therapy research clinic. Subjects: Sixty subjects (35±11.22 years) with TMD, and restricted mobility of the mandibular condyles and the first cervical vertebrae, were recruited and randomized to either a control group (CG) (n=30) or an experimental group (EG) (n=30). Interventions: The CG underwent a neuromuscular technique over the masseter muscles and passive hamstring muscle stretching. A suboccipital muscle inhibition technique was added to this protocol in the EG. Outcome measures: Primary measurements were made of vertical mouth opening and pressure pain threshold of the masseter muscles. Secondary outcome measures included pressure algometry of the trigeminal nerve, suboccipital range of motion, and lumbar spine mobility, assessed with the sit-and-reach (SAR) test and lumbar forward bending. All evaluations were collected at baseline and immediately after intervention. Results: In the intragroup comparison, the EG observed an increase in suboccipital flexion (p<0.001; F1,29=14.47; R(2)=0.33) and the SAR test (p=0.009; F1,29=7.89; R(2)=0.21). No significant differences were found in the between-group comparison for any variable (p>0.05). Conclusion: The inclusion of a myofascial induction maneuver in a protocol combining local (neuromuscular treatment) and distal techniques (hamstring stretching) in subjects with TMD has no impact on improving mouth opening, suboccipital and lumbar mobility, and orofacial sensitivity to mechanical pressure.