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.
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.
Raumens susitraukimo jėga, užregistruota tuojau po aktyvaus raumens susitraukimo, yra mažesnė už jėgą, užregistruo-tą izometrinio susitraukimo metu (lyginama esant tokiam pat raumens ilgiui) (Abbott, Aubert, 1952; Sugi, Tsuchiya, 1988; Edman et al., 1993; Herzog, 1998; De Ruiter et al., 1998; Kosterina et al., 2008; Rode et al., 2009; Tilp et al., 2009). Toks reiškinys vadinamas po raumens susitraukimo atsiradęs jėgos sumažėjimas arba jėgos depresija (JD) (Abbott, Aubert, 1952; Herzog, 1998; De Ruiter et al., 1998). Raumenų jėgos sumažėjimas po raumens susitraukimo yra didesnis, kai raumuo susitraukia didesne jėga (De Ruiter et al., 1998), didesne amplitude (Herzog, 1998; De Ruiter et al., 1998), mažesniu greičiu (De Ruiter et al., 1998; Herzog et al., 2003) ir susitraukdamas atlieka didesnį darbą (Herzog, 1998; Herzog et al., 2000). Dar nėra žinoma, kaip JD priklauso nuo raumenų nuovargio, treniruotumo, raumenų atrofi jos ar raumenų ligų. Todėl manytume: norint geriau suprasti griaučių raumenų funkciją svarbu nustatyti, ar raumenų nuovargis gali paveikti JD.Tyrimo tikslas — nustatyti, ar skirtingais elektrostimuliacijos dažniais valingai aktyvavus keturgalvį šlaunies raumenį nuovargis veikia po raumens sutrumpėjimo atsiradusią JD. Sveiki nesportuojantys vyrai (n = 8) atliko izometri-nį—koncertinį—izometrinį (Izom—Kon—Izom) ir izometrinį raumens susitraukimą (IZO), stimuliuojant keturgalvį šlaunies raumenį 20 Hz, 50 Hz dažnio stimulu ir išugdant maksimaliąją valingą jėgą (MVJ). Norint sukelti raumenų nuovargį buvo atliekamas ekscentrinis krūvis — 10 serijų po 10 kartojimų (kojos tiesimo amplitudė — nuo 110° iki 60° kampo per kelio sąnarį). Izokinetinis dinamometras neleido išlaikyti ištiestos kojos ir lenkė ją 120° / s greičiu. Kreatinkinazės (CK) aktyvumas kraujo serume buvo vertinamas prieš krūvį ir praėjus 48 h po jo. Raumenų JD, stimuliuojant keturgalvį šlaunies raumenį mažais dažniais, po krūvio reikšmingai padidėja vėlesnėje atsigavimo fazėje (p < 0,05). Raumenų pažeidą sukeliantis ekscentrinis krūvis neveikia JD, kuomet keturgalvis šlaunies raumuo stimuliuojamas dideliais dažniais ar kai raumenų jėga išugdoma didžiausiomis valios pastangomis.
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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