Search results for "joint"
showing 10 items of 1472 documents
Three-dimensional distribution of trabecular bone density and cortical thickness in the distal humerus
2008
One major barrier to osteosynthesis in distal humeral fractures is poor bone quality. This study was an attempt to measure the bone quality in the distal humerus.We measured the distribution of total bone mineral density (BMD), trabecular BMD (tBMD), and cortical thickness (CTh) in the distal humerus using peripheral quantitive computed tomography. Four slices in the infracondylar, supracondylar, and distal disphyseal regions of 25 human cadaver humeri were investigated.Total BMD decreased continuously from the distal diaphysis to the trochlea. Within the infracondylar region, the capitellum was the region of lowest tBMD and CTh (P.001). Measurements in anterior regions were higher than in …
Emotional communication in the context of joint attention for food stimuli: Effects on attentional and affective processing
2014
Guided by distinct theoretical frameworks (the embodiment theories, shared-signal hypothesis, and appraisal theories), we examined the effects of gaze direction and emotional expressions (joy, disgust, and neutral) of virtual characters on attention orienting and affective reactivity of participants while they were engaged in joint attention for food stimuli contrasted by preference (disliked, moderately liked, and liked). The participants were exposed to videos of avatars looking at food and displaying facial expressions with their gaze directed either toward the food only or toward the food and participants consecutively. We recorded eye-tracking responses, heart rate, facial electromyogr…
Modular Control of Pointing beyond Arm's Length
2009
Hand reaching and bipedal equilibrium are two important functions of the human motor behavior. However, how the brain plans goal-oriented actions combining target reaching with equilibrium regulation is not yet clearly understood. An important question is whether postural control and reaching are integrated in one single module or controlled separately. Here, we show that postural control and reaching motor commands are processed by means of a modular and flexible organization. Principal component and correlation analyses between pairs of angles were used to extract global and local coupling during a whole-body pointing beyond arm's length. A low-dimensional organization of the redundant ki…
Human isometric force production and electromyogram activity of knee extensor muscles in water and on dry land.
1999
This study was designed to determine trial-to-trial and day-to-day reproducibility of isometric force and electromyogram activity (EMG) of the knee extensor muscles in water and on dry land as well as to make comparisons between the two training conditions in muscle activity and force production. A group of 20 healthy subjects (12 women and 8 men) were tested three times over 2 weeks. A measurement session consisted of recordings of maximal and submaximal isometric knee extension force with simultaneous recording of surface EMG from the vastus medialis, vastus lateralis and biceps femoris muscles. To ensure identical measurement conditions the same patient elevator chair was used in both th…
Electromechanical behaviour of human muscles in vertical jumps
1982
The relationships of muscle structure to the potentiation of myoelectrical activity and to the use of prestretching in five lower limb muscles were studied in different vertical jumping conditions. The subjects for the study were six male students, divided according to the muscle fiber distribution in m. vastus lateralis into “fast” and “slow” groups. The subjects performed vertical jumps (1) from a static squatting position (SJ), (2) with a preliminary counter movement (CMJ) and (3) after dropping (DJ) from five different heights. Myoelectrical (EMG) activity was recorded from mm. gluteus maximus, vastus lateralis, vastus medialis, rectus femoris and gastrocnemius in each jumping condition…
Effects of muscle – tendon length on joint moment and power during sprint starts
2005
The aim of this study was to examine the effects of muscle-tendon length on joint moment and power during maximal sprint starts. Nine male sprinters performed maximal sprint starts from the blocks that were adjusted either to 40 degrees or 65 degrees to the horizontal. Ground reaction forces were recorded at 833 Hz using a force platform and kinematic data were recorded at 200 Hz with a film camera. Joint moments and powers were analysed using kinematic and kinetic data. Muscle - tendon lengths of the medial gastrocnemius, soleus, vastus medialis, rectus femoris and biceps femoris were calculated from the set position to the end of the first single leg contact. The results indicated that bl…
Immediate effects of active cranio-cervical flexion exercise versus passive mobilisation of the upper cervical spine on pain and performance on the c…
2014
This study compared the immediate effects of an assisted plus active cranio-cervical flexion exercise (exercise group) versus a passive mobilisation plus assisted cranio-cervical flexion (mobilisation group) on performance of the cranio-cervical flexion test (CCFT), cervical range of motion (ROM) and pain in patients with chronic neck pain. Eighteen volunteers with chronic idiopathic neck pain participated in the study and were randomised to one of the two intervention groups. Current level of pain, cervical ROM and pain perceived during movement, pressure pain threshold (PPT) and surface electromyography (EMG) during performance of the CCFT were measured before and immediately after the in…
Muscle tone in different joint positions and at submaximal isometric torque levels
2007
The aim was to evaluate the tone and electric activity of the quadriceps muscle at rest and different torque levels. The second aim was to study whether thickness of soft tissues and change in the joint position would affect muscle tone. Eighteen healthy subjects participated. Computerized muscle tonometer (CMT) and surface electromyography (sEMG) measurements were performed: seated, first at rest with leg straight and then with the knee at 60 degrees . Thereafter measurements were obtained at levels of 80, 60, 40 and 20% of the maximum isometric torque at the same knee angle. Thickness of skin, subcutis and muscle was measured by ultrasound. The CMT values taken were the depth the indenter…
Contribution of the tendinous tissue to force enhancement during stretch–shortening cycle exercise depends on the prestretch and concentric phase int…
2005
When the prestretch intensity and concentric work are increased in stretch-shortening cycle (SSC) exercises, the utilization of the elastic energy can increase during the concentric phase. In order to further understand this process during SSC exercises, the interaction between fascicle-tendinous tissues (TT) of the vastus lateralis (VL) muscle was examined under different prestretch and rebound intensity drop jumps. Ten male subjects participated in the study. Direct VL fascicle lengths (N = 10) and in vivo patellar tendon force (N = 1) were measured together with the electromyographic (EMG) activity of VL during the trials. With increasing drop height but the same rebound height condition…
Neomuscular fatigue to power loading using a weight-stack device fitted with or without additional rubber band resistance
2014
The addition of a rubber band (RB) to traditional weight-based resistance may be beneficial regarding the deceleration phase common during explosive power actions with light weights. This would lead to greater force and muscle activity during the latter part of the movement, but this may influence the distribution of neuromuscular fatigue. Fifteen men performed 2 knee extension power loadings (5 × 5 × 40% of 1 repetition maximum [1RM]) using a typical weight-stack device without (WS) and with the addition of a RB (WS + RB) in a crossover design. Concentric contractions were performed as fast as possible, and analyzed for torque, velocity, power, and vastus lateralis and medialis surface ele…