Research background and hypothesis. There is much research information about the relationship between the knee joint angle and the quadriceps muscle torque (Mohamed et al., 2002), but still we lack evidence about the relationship between ankle angle and calf muscle torque. Research aim. The purpose of this research was to establish the dependence of maximal voluntary contraction (MVC) and electrical stimulation (ES)-evoked torque and calf muscle electrical activity (EMG) on different ankle plantar and dorsal fl exion angles. We hypothesized that the calf muscle MVC and ES-evoked torque as well as muscle EMG amplitude would increase with increasing muscle length (i. . increasing ankle angle).Research methods. The subjects in the research were ten non-trained men. Calf plantar and dorsal fl exors muscle ES and MVC torque were tested at eight different ankle angles (–25 o ; –15 o ; –5 o ; 0 o ; 15 o ; 25 o ; 35 o ; 45 o ) which were chosen in randomized sequence. The tibialis anterior, soleus, gastrocnemius lateralis and medialis muscle EMG were measured during muscle MVC.Research results. The results showed that the highest ES-evoked and MVC developed torque of plantar fl exion muscles was at –25° ankle angle (149.1 ± 31.6 N·m and 207.8 ± 38.1 N·m, respectively), while the highest dorsal fl exion MVC muscle torque was at 25° ankle angle (47.2 ± 8.1 N·m). However, dorsal fl exion muscle MVC torque increased with the muscle length only until 25° ankle angle. Discussion and conclusions. Plantar flexion muscle electrical stimulation evoked and plantar / dorsal fl exion muscle maximal voluntary contraction torques are highest at that ankle angle where muscle length is the longest.
It has been established that muscle torque variability determines movement stability during the task [1]. Calf muscle weakness, ankle range of motion reduction and postural misbalance are common pathological limitations after Achilles tendon rupture (ATR). Most studies analyse rehabilitation influence for muscle strength and body balance, but there is a lack of information about calf muscle torque variability. The aim of the study was to determine ankle plantar flexion and dorsal flexion muscle maximal voluntary contraction torque and variability Q. Organization and methods. We measured five males, (aged 29 ± 6) after 6.5 – week surgery of ATR. Participants performed isometric ankle flexion and extension force with injured and non-injured legs. Muscles maximal voluntary contraction (MVC) torque and torque variability were measured at –15°; 0°; 15° angles. The variability of target force was 20% of MVC torque. Rehabilitation programme consisted of balance, muscle strength and stretching exercises. Calf muscle MVC torque and variability were observed before and after 8-week rehabilitation. The results of the research. We determined that after physiotherapy the injured and the non-injured leg isometric ankle flexion and extension muscle MVC torque increased and muscle torque variability decreased.Keywords: muscle torque variability, isometric maximal voluntary contraction torque, rehabilitation suformavimas.
Research background and hypothesis. Anterior cruciate ligament (ACL) of the knee joint is often quite a fragile structure of the knee. After the rupture of ACL neuromuscular control worsens and sensorimotor system breaks down (Risberg et al., 2007), muscle activation is poor and muscle strength decreases (Croce, Miller, 2006). Some authors have reported greater strength loss in quadriceps femoris than in hamstring femoris muscle (Busch-Joseph et al., 2001; Neeter et al., 2006), therefore we hypothesized that strength loss in knee extensors may affect hamstring/quadriceps torque (H:Q) ratio. Research aim of this study was to investigate knee extensors and fl exors isometric and dynamic torque and H:Q ratio alterations before ACL surgery and after rehabilitation.Research methods. Ten volunteers with ACL ruptured knee where tested before surgery and after rehabilitation. Isokinetic dynamometer was used for this testing. Maximal isometric torque was performed during fl exion and extension at 90°, 60º knee angles. Dynamic torque was performed at 30, 180, 300º/s angular velocities.Research results. Results of this study show that after rehabilitation isometric and dynamic torque of the involved leg decreased. Isometric fl exion and extension torque of the uninjured leg was greater than that of the injured leg, but after rehabilitation the extension torque of the injured leg was lower than that before surgery. Discussion and conclusions. Before ACL surgery and after rehabilitation quadriceps femoris muscle torque of the uninjured leg was more affected than hamstring femoris muscle torque. After rehabilitation H:Q ratio of the injured leg was not dependent on angular velocity and knee joint angle.
Research background and hypothesis. Most studies are based on elderly subjects’ results, so there is a need to explore if motor performance changes begin in the middle age. We hypothesize that (i) middle-aged subjects use “play it safe” strategy, which depends on the type of tasks (simple vs. random choice); (ii) middle-aged subjects will show higher intra-individual performance variability compared to young adults, furthermore, simple task will show lower performance variability.Research aim was to establish if there were any movement performance differences during simple and random choice motor task performance between young and middle-aged adults.Research methods. Middle-aged and young adults performed two speed-accuracy tasks. During simple task participants had to reach the same target which appeared in the same place and during random choice task the target appeared randomly in one of the three different places.Research results. Data showed that middle-aged group had slower (p < 0.05) reaction time and maximal velocity, whereas movement path length was more accurate (p < 0.05) than that in the young adult group. Comparing different tasks it was observed that during simple task reaction time was faster (p < 0.05) than in the random choice task in both groups. Intra-individual variability of reaction time and maximal velocity was higher (p < 0.05) in the middle-aged group, whereas no changes were observed between different tasks.Discussion and conclusion. Motor performance strategy “play it safe” is already observed for the middle-aged population: they decrease maximal velocity and reaction time in order to make movement more accurate. Additionally, they demonstrate task-independent higher intra-individual variability of reaction time and maximal velocity showing changes in CNS integrity compared to young adults.
Changes in gait after traumatic brain injury (TBI) are very important for evaluation, clinical reasoning and forintervention programs. Most studies analyze gait during acute phase, but there is lack of information during post-acute period. The aim of the research was to determine gait biomechanical joint angles and centre of mass displacement changes during post-acute TBI rehabilitation. Participant was a 21-year-old male, after severe TBI, 2 years after trauma. Biomechanical joints angles and centre of mass displacement changes were observed during 3D gait analysis. The subject was asked to walk straight 6 meters, 18 times at his preferred comfortable pace. During walking 1–2 minute breaks were made. Intensive 5 week program was composed of physiotherapy (3 times per week) and yoga (2 times per week). Physiotherapy included stretching, coordination, balance and weight-bearing exercises. Yoga was performed to built core stability, train flexibility and diminish muscle tone. After 5 week rehabilitation statistically significant changes were observed in the centre of mass displacement and in lower extremities and lumbar biomechanics (p < 0.05). After procedures trunk flexion and trunk lateral flexion, lateral pelvic tilt increased, while anterior pelvic tilt decreased (p < 0.05). Hip extension at terminal stance increased, as well while hip adduction in stance phase decreased (p < 0.05). Statistically significant reduction was observed in knee flexion at initial contact, mid-stance and midswing phase (p < 0.05). Prevalent knee flexion at initial contact, observed before rehabilitation, decreased after it (p < 0.05). After the procedure lateral centre of mass displacement decreased and vertical centre of mass displacement increased (p < 0.05). Five weeks of rehabilitation composed of traditional physiotherapy and yoga is effective for gait quality treatment. However, further research is necessary to determine gait biomechanical joint angles and dynamic balance improvements during severe post-acute TBI.Keywords: head injury, walking, balance.
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