Search results for "Tendons"
showing 10 items of 68 documents
Acute effects of dynamic stretching on mechanical properties result from both muscle-tendon stretching and muscle warm-up
2019
We investigated the acute effects of dynamic stretching on mechanical properties of plantar flexor muscles and tested the hypothesis that it would result from an interaction between muscle-tendon stretching and muscle warm-up. To test the stretching effect, dynamic stretching (DS) was compared to static stretching (SS). To test the warm-up effect, DS was compared to submaximal isometric muscle activity (SIMA) with similar contraction intensity. A control condition served as reference. These four conditioning activities were time matched (2×20s) and tested on separate days on 13 volunteers. Electrical neurostimulation was applied to investigate muscle mechanical properties (peak doublet torq…
Triceps surae muscle-tendon properties in older endurance- and sprint-trained athletes
2015
Previous studies have shown that aging is associated with alterations in muscle architecture and tendon properties (Morse CI, Thom JM, Birch KM, Narici MV. Acta Physiol Scand 183: 291–298, 2005; Narici MV, Maganaris CN, Reeves ND, Capodaglio P. J Appl Physiol 95: 2229–2234, 2003; Stenroth L, Peltonen J, Cronin NJ, Sipila S, Finni T. J Appl Physiol 113: 1537–1544, 2012). However, the possible influence of different types of regular exercise loading on muscle architecture and tendon properties in older adults is poorly understood. To address this, triceps surae muscle-tendon properties were examined in older male endurance (OE, n = 10, age = 74.0 ± 2.8 yr) and sprint runners (OS, n = 10, age…
Mechanically induced reflex responses in human triceps brachii.
1986
The short and long latency reflex responses of human triceps brachii muscle were recorded in 14 healthy volunteers. An electromechanical hammer was used to stretch the muscle and recordings were made from a surface electromyogram. The monosynaptic tendon reflex occurred at a mean latency of 12.5 ms (SE 0.7 ms). Later responses were observed in activated conditions (weak force production, preparatory period) at a mean latency of 62.8 ms (SE 3.5 ms). The amplitude of the short latency reflex increased during weak tension, the long latency reflex amplitude seemed to increase during the preparatory period testing. The amplitude increases can be attributed to increased lower motoneuron excitabil…
Afferent contribution to locomotor muscle activity during unconstrained overground human walking:an analysis of triceps surae muscle fascicles
2010
Plantar flexor series elasticity can be used to dissociate muscle–fascicle and muscle–tendon behavior and thus afferent feedback during human walking. We used electromyography (EMG) and high-speed ultrasonography concomitantly to monitor muscle activity and muscle fascicle behavior in 19 healthy volunteers as they walked across a platform. On random trials, the platform was dropped (8 cm, 0.9 g acceleration) or held at a small inclination (up to ±3° in the parasagittal plane) with respect to level ground. Dropping the platform in the mid and late phases of stance produced a depression in the soleus muscle activity with an onset latency of about 50 ms. The reduction in ground reaction force…
Individual Region- and Muscle-specific Hamstring Activity at Different Running Speeds
2019
Introduction \ud Hamstring strain injuries typically occur in the proximal biceps femoris long head (BFlh) at high running speeds. Strain magnitude seems to be the primary determinant of strain injury, and may be regulated by muscle activation. In running, BFlh strain is largest in the proximal region, especially at high speeds. However, region-specific activity has not been examined. This study examined the proximal–distal and intermuscular activity of BFlh and semitendinosus (ST) as a function of increasing running speed.\ud \ud Methods \ud Thirteen participants ran at steady speeds of 4.1 (slow), 5.4 (moderate), and 6.8 m·s−1 (fast) on a treadmill. Region- and muscle-specific EMG activit…
Shock wave therapy versus conventional surgery in the treatment of calcifying tendinitis of the shoulder.
2001
A prospective quasirandomized study was performed to compare the effects of surgical extirpation (Group I, 29 patients) with the outcome after high-energy extracorporeal shock wave therapy (Group II, 50 patients; 3,000 impulses of an energy flux density of 0.6 mJ/mm2) in patients with a chronic calcifying tendinitis in the supraspinatus tendon. Symptoms and demographic data of the two groups were comparable. According to the University of California Los Angeles Rating System, the mean score in Group I was 30 points with 75% good or excellent results after 12 months, and 32 points with 90% good or excellent results after 24 months. Radiologically, there was no calcific deposit in 85% of the …
Intensity- and muscle-specific fascicle behavior during human drop jumps.
2006
The present study was designed to examine fascicle-tendon interaction in the synergistic medial gastrocnemius (MG) and soleus (Sol) muscles during drop jumps (DJ) performed from different drop heights (DH). Eight subjects performed unilateral DJ with maximal rebounds on a sledge apparatus from different DH. During the exercises, fascicle lengths (using ultrasonography) and electromyographic activities were recorded. The results showed that the fascicles of the MG and Sol muscles behaved differently during the contact phase, but the whole muscle-tendon unit and its tendinous tissue lengthened before shortening in both muscles. The Sol fascicles also lengthened before shortening during the g…
Spectrum of mutations and phenotypic expression in patients with autosomal dominant hypercholesterolemia identified in Italy.
2013
Abstract Objective To determine the spectrum of gene mutations and the genotype–phenotype correlations in patients with Autosomal Dominant Hypercholesterolemia (ADH) identified in Italy. Methods The resequencing of LDLR , PCSK9 genes and a selected region of APOB gene were conducted in 1018 index subjects clinically heterozygous ADH and in 52 patients clinically homozygous ADH. The analysis was also extended to 1008 family members of mutation positive subjects. Results Mutations were detected in 832 individuals: 97.4% with LDLR mutations, 2.2% with APOB mutations and 0.36% with PCSK9 mutations. Among the patients with homozygous ADH, 51 were carriers of LDLR mutations and one was an LDLR / …
How preconditioning and pretensioning of grafts used in ACLigaments surgical reconstruction are influenced by their mechanical time-dependent charact…
2021
Abstract Purpose Consensus about a pre-implant preparation protocol adaptable to any graft used in Anterior Cruciate Ligament reconstruction is still lacking. In fact, there is not agreement on reliable metrics that consider both specific graft dimensional characteristics, such as its diameter, and the inherent properties of its constitutive material, i.e. ligaments or tendons. Aim of the present study was to investigate and propose the applied engineering stress as a possible metrics. Methods Preconditioning and pretensioning protocol involved groups of grafts with different section (10 or 32 mm2) and materials (i.e. human patellar and hamstring tendons, and synthetic grafts). A 140 N load…
Shortstop Recruits EB1/APC1 and Promotes Microtubule Assembly at the Muscle-Tendon Junction
2003
Abstract Background: Shot (previously named Kakapo), is a Drosophila Plakin family member containing both Actin binding and microtubule binding domains. In Drosophila , it is required for a wide range of processes, including axon extension, dendrite formation, axonal terminal arborization at the neuromuscular junction, tendon cell development, and adhesion of wing epithelium. Results: To address how Shot exerts its activity at the molecular level, we investigated the molecular interactions of Shot with candidate proteins in mature larval tendon cells. We show that Shot colocalizes with EB1/APC1 and with a compact microtubule array extending between the muscle-tendon junction and the cuticle…