Search results for "Musculoskeletal System"
showing 10 items of 795 documents
In vivo achilles tendon loading' during jumping in humans
1995
Elastic behaviour of the human tendomuscular system during jumping was investigated by determination of the in vivo Achilles tendon force. A buckle-type transducer was implanted under local anaesthesia around the right Achilles tendon of an adult subject. After calibration, the Achilles tendon force was recorded together with the triceps surae muscle electromyogram activity and high speed filming and ground reaction force during: a maximal vertical jump from a squat position, a maximal vertical jump from an erect standing position with a preliminary counter-movement, and repetitive submaximal hopping on the spot. Jumping heights were 33, 40 and 7 cm in the squat, the counter movement, and t…
Mechanical Properties of Human Patellar Tendon at the Hierarchical levels of Tendon and Fibril
2012
Tendons are strong hierarchical structures, but how tensile forces are transmitted between different levels remains incompletely understood. Collagen fibrils are thought to be primary determinants of whole tendon properties, and therefore we hypothesized that the whole human patellar tendon and its distinct collagen fibrils would display similar mechanical properties. Human patellar tendons ( n = 5) were mechanically tested in vivo by ultrasonography. Biopsies were obtained from each tendon, and individual collagen fibrils were dissected and tested mechanically by atomic force microscopy. The Young's modulus was 2.0 ± 0.5 GPa, and the toe region reached 3.3 ± 1.9% strain in whole patellar …
Force in the Achilles Tendon During Walking With Ankle Foot Orthosis
2009
Background Ankle foot orthoses are used for postoperative treatment of Achilles tendon ruptures and decrease calf muscle electromyography activity during walking. Hypothesis Achilles tendon load decreases with increased restriction of dorsiflexion and is associated with decreased triceps surae activity. Study Design Controlled laboratory study. Methods In 8 subjects, the maximum force and rate of force development in the Achilles tendon were measured with an optic fiber technique, and the activity of the gastrocnemius, soleus, and tibialis anterior muscles was recorded using electromyography. Trial conditions were walking barefoot and wearing an ankle-foot orthoses set in 3 different positi…
The influence of a depressed scapular alignment on upper limb neural tissue mechanosensitivity and local pressure pain sensitivity
2017
A depressed scapular alignment could lead to prolonged and repetitive stress or compression of the brachial plexus, resulting in sensitization of neural tissue. However, no study has investigated the influence of alignment of the scapulae on sensitization of upper limb neural tissue in otherwise asymptomatic people. In this case-control study, we investigate the influence of a depressed scapular alignment on mechanosensitivity of the upper limb peripheral nervous system as well as pressure pain thresholds (PPT). Asymptomatic individuals with neutral vertical scapular alignment (n = 25) or depressed scapular alignment (n = 25) participated. We measured the upper limb neurodynamic test (ULNT1…
Clavicle aseptic nonunion: is there a place for cortical allogenic strut graft?
2017
Abstract We investigated functional and radiological outcome in 57 cases of midshaft clavicle nonunion treated with open reduction and internal fixation with plate and screws over a 13 year-period. Intercalary bone graft was used in 42 patients; opposite autologous strut graft was used in 31 cases to provide mechanical support to the host bone. Patients were analysed using chart and radiological review and assessed with DASH questionnaire obtained at the latest follow-up. 37 patients were male while 20 were females, with a mean age of 35 years (63–17). All cases were of nonunion, 35 atrophic and 22 hypertrophic. The dominant side was injured in 32 cases and the non dominant in 25 cases. Pri…
Bone Mineral Density and Long Term Exercise
1993
Evidence in human studies of the association of long term habitual exercise with bone mineral content (BMC) and density (BMD) largely comes from studies in athletes. In young adults, the highest BMC and BMD values have been found in strength and power-trained athletes, while endurance activities such as long distance running and swimming seem less effective with regard to peak bone density. Intensive endurance training may even be associated with amenorrhoea and decreased trabecular bone density in young females. However, after menopause female athletes show greater bone mass indicating that they do not share the accelerated decline in BMC observed in a nonathletic population. Middle-aged a…
Interaction between pre-landing activities and stiffness regulation of the knee joint musculoskeletal system in the drop jump: implications to perfor…
2002
The purpose of the present study was to investigate the interaction between the pre-landing activities and the stiffness regulation of the knee joint musculoskeletal system and the takeoff speed during a drop jump (DJ). Nine healthy male subjects performed a DJ test from the height of 50 cm. The surface electromyographic (EMG) activity of the vastus lateralis (VL) muscle was recorded to evaluate both the pre-landing and post-landing muscle activation levels. Simultaneous recording of the jumping motion and ground reaction force was performed by a high-speed video camera (100 frames x s(-1)), and a force platform was employed to allow joint moment analysis. Joint stiffness was calculated by …
In vivo mechanical response of human Achilles tendon to a single bout of hopping exercise
2010
SUMMARY Stiffness of the human Achilles tendon (AT) was determined in vivo before and after a single bout of hopping exercise. It was hypothesized, based on published data using in vitro specimens, that a reduction in AT stiffness may occur after just 1000 loading cycles at physiological stress levels. Ten healthy subjects performed two-legged hopping exercise consisting of 1150–2600 high impacts. Tendon stiffness was determined in several isometric ramp contractions [20%, 40%, 60%, 80% and 100% maximum voluntary contraction (MVC)] during which tendon elongation was measured using ultrasonography and two cameras. Tendon force was calculated by dividing measured ankle torque by magnetic reso…
Thigh-length versus below-knee compression elastic stockings for prevention of the postthrombotic syndrome in patients with proximal-venous thrombosi…
2012
Abstract Although below-knee compression elastic stockings (CES) are effective for the prevention of the postthrombotic syndrome (PTS), a substantial number of patients with deep venous thrombosis still develop PTS. In the present open-label, randomized clinical trial, we compared thigh-length with below-knee CES for the prevention of PTS. A total of 267 patients with the first episode of proximal deep venous thrombosis were randomized to wear either thigh-length or below-knee CES for 2 years. After 3, 6, 12, 18, 24, and 36 months, they were assessed for PTS manifestations according to the Villalta scale. PTS developed in 44 (32.6%) of the 135 patients randomized to thigh-length CES and in …
Effect of bike-fit in the perception of comfort, fatigue and pain
2016
The aim of this study was to assess the influence of different bike positions on the perception of fatigue, pain and comfort. Twenty cyclists underwent three tests that involved cycling for 45 min at their individual 50% peak aerobic power output while adopting different positions on the bike. Participants performed the cycling tests adopting three positions defined by two parameters (knee flexion angle [20°, 30°, 40°] and trunk flexion angle [35°, 45°, 55°]) in random order. Angles were measured using a 2D motion analysis system during cycling and applying Fonda's correction factor. Perceptions of comfort, fatigue and pain were reported before the end of each test. The combination of 40° k…