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hamstring center of pressure

Bart Dingenen, Luc Janssens, Steven Claes, Johan Bellemans, Filip F Staes
BACKGROUND: Previous studies mainly focused on muscles at the operated knee after anterior cruciate ligament reconstruction, less on muscles around other joints of the operated and non-operated leg. The aim of this study was to investigate muscle activation onset times during the transition from double-leg stance to single-leg stance in anterior cruciate ligament reconstructed subjects. METHODS: Lower extremity muscle activation onset times of both legs of 20 fully returned to sport anterior cruciate ligament reconstructed subjects and 20 non-injured control subjects were measured during the transition from double-leg stance to single-leg stance in eyes open and eyes closed conditions...
2016: Clinical Biomechanics
Kushal S Shah, Archana Saranathan, Bharath Koya, John J Elias
A finite element analysis (FEA) modeling technique has been developed to characterize how varying the orientation of the patellar tendon influences the patellofemoral pressure distribution. To evaluate the accuracy of the technique, models were created from MRI images to represent five knees that were previously tested in vitro to determine the influence of hamstrings loading on patellofemoral contact pressures. Hamstrings loading increased the lateral and posterior orientation of the patellar tendon. Each model was loaded at 40°, 60°, and 80° of flexion with quadriceps force vectors representing the experimental loading conditions...
2015: Computer Methods in Biomechanics and Biomedical Engineering
S Ghroubi, W Elleuch, L Abid, M Abdenadher, S Kammoun, M H Elleuch
OBJECTIVE: Study the effect of muscle strength training on muscle strength, maximal oxygen uptake (VO2max), hemodynamic and anthropometric parameters as well as quality of life after coronary artery bypass grafting (CABG). METHODS: After CABG surgery, 32 patients were randomized into two groups. The first group was to perform aerobic-type training with a cycle ergometer (AT=16). The second group was to perform low-intensity muscle strength training of the quadriceps and hamstrings using an isokinetic dynamometer (i...
March 2013: Annals of Physical and Rehabilitation Medicine
Hidehito Tomita, Yoshiki Fukaya, Kenji Totsuka, Yuri Tsukahara
This study aimed to determine whether individuals with spastic diplegic cerebral palsy (SDCP) have deficits in anticipatory inhibition of postural muscle activity. Nine individuals with SDCP (SDCP group, 3 female and 6 male, 13-24 yr of age) and nine age- and sex-matched individuals without disability (control group) participated in this study. Participants stood on a force platform, which was used to measure the position of the center of pressure (CoP), while holding a light or heavy load in front of their bodies...
April 2013: Journal of Neurophysiology
Ashleigh Kennedy, Arnaud Guevel, Heidi Sveistrup
The aim of this study was to determine whether and how young participants modulate their postural response to compensate for postural muscle fatigue during predictable but externally initiated continuous and oscillatory perturbations. Twelve participants performed ten postural trials before and after an ankle muscle fatigue protocol. Each postural trial was 1 min long and consisted of continuous backward and forward oscillations of the platform. Fatigue was induced by intermittent, bilateral isometric contractions of the ankle plantar- and dorsiflexors until the force production was reduced to 50 % of the pre-fatigue maximal voluntary contraction...
December 2012: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Guadalupe X Ayala et al.
OBJECTIVES: This within-participants, single time-series study tested a train-the-trainer, promotor-based physical activity (PA) intervention to improve fitness and health indicators. METHODS: Thirty unpaid promotores were trained to promote PA through free exercise classes. Measurements of 337 female community participants at baseline, 6 months, and 12 months assessed changes in health indicators, including systolic and diastolic blood pressure, waist circumference, body mass index (defined as weight in kilograms divided by the square of height in meters), aerobic fitness, and hamstring flexibility, as well as self-reported health indicators (PA, depression) and psychosocial factors (barriers, self-efficacy, and social support-all specific to PA)...
December 2011: American Journal of Public Health
Yohei Shimokochi, Sae Yong Lee, Sandra J Shultz, Randy J Schmitz
CONTEXT: Excessive quadriceps contraction with insufficient hamstrings muscle cocontraction has been shown to be a possible contributing factor for noncontact anterior cruciate ligament (ACL) injuries. Assessing the relationships among lower extremity internal moments may provide some insight into avoiding muscle contraction patterns that increase ACL injury risk. OBJECTIVE: To examine the relationships of knee-extensor moment with ankle plantar-flexor and hip-extensor moments and to examine the relationship between knee moment and center of pressure as a measure of neuromuscular response to center-of-mass position...
January 2009: Journal of Athletic Training
Neeta Kanekar, Marcio J Santos, Alexander S Aruin
OBJECTIVE: To investigate the effect of fatigue of postural and focal muscles on anticipatory postural adjustments (APAs). METHODS: Nine healthy adults performed rapid bilateral arm raising movements before and after isometric hamstring (postural) and deltoid (focal/prime mover) muscle fatigue. Muscle force and peak acceleration of the arm movements were recorded to assess the presence of fatigue. Ground reaction forces, EMG activity of trunk and leg muscles and center of pressure (COP) displacements were recorded and quantified within the time intervals typical of APAs...
October 2008: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
A J Strang, H J Choi, W P Berg
AIM: The aim of the study was to investigate the influence of exhausting aerobic exercise on the timing of anticipatory postural adjustments (APAs). METHODS: The APAs of 12 participants were recorded at baseline, after a .VO2max running test, and again following a 45-min rest period. APAs were induced using a rapid bilateral arm-raising maneuver, and were analyzed in the rectus abdominis, hamstring group, gluteal group, and lumbar and thoracic paraspinal muscles using electromyography...
March 2008: Journal of Sports Medicine and Physical Fitness
Gregory D Myer, Kevin R Ford, Jensen L Brent, Timothy E Hewett
Neuromuscular training protocols that include both plyometrics and dynamic balance exercises can significantly improve biomechanics and neuromuscular performance and reduce anterior cruciate ligament injury risk in female athletes. The purpose of this study was to compare the effects of plyometrics (PLYO) versus dynamic stabilization and balance training (BAL) on power, balance, strength, and landing force in female athletes. Either PLYO or BAL were included as a component of a dynamic neuromuscular training regimen that reduced measures related to ACL injury and increased measures of performance...
May 2006: Journal of Strength and Conditioning Research
Yoshihiko Yamazaki, Masataka Suzuki, Tetsuo Ohkuwa, Hiroshi Itoh
Nine healthy subjects standing upright, initiated small, medium and large (S, M and L conditions, respectively) forward movements of their right (Rt) arm together with backward movements of their left (Lt) arm. They also performed medium-size movements while holding a 3 kg dumbbell in each hand (D condition). Movements started with the arm hanging alongside the body and ended when the shoulder reached a desired orientation. The arm and trunk movements were videotaped and recorded by accelerometers taped to the wrists, shoulders, and hips bilaterally...
September 30, 2005: Brain Research Bulletin
G Mochizuki, T D Ivanova, S J Garland
The muscle activation patterns in anterior and posterior leg muscles were investigated with two types of perturbations to standing balance. Subjects stood with each foot on adjacent force platforms and performed arm flexion movements to shoulder height. Nine subjects performed ten repetitions unilaterally and bilaterally at 100, 75, 50, 25, and 12.5% of maximal acceleration as measured by an accelerometer placed on the dominant hand. Four subjects also performed the fastest movements while leaning forwards and backwards...
April 2004: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
L Sundermier, M Woollacott, N Roncesvalles, J Jensen
This cross-sectional study examined electromyographic (EMG) and kinetic variables during reactive balance responses in children grouped according to developmental level as compared with chronological age. Purposes were to explore relationships between the two types of variables and the effectiveness of the two grouping methods. Forty-four children between 9 months and 10 years old were tested for reactive balance control on a moveable platform. Surface electrodes measured EMG activity in the gastrocnemius (GA), hamstrings (HA), paraspinals (PS), tibialis anterior (TA), quadriceps (QA), and abdominal (AB) muscles...
February 2001: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
T Szturm, B Fallang
Different movement synergies used to restore balance in response to sudden support surface displacements have been described, which include the ankle movement synergy and a number of multisegmental movement synergies. The purpose of this study was to extend the analysis of the effects of stimulus magnitude on the pattern and scaling of balance reactions to larger magnitudes of balance disturbances, and to other types of balance disturbances, in particular, forward translations (FT), backward translations (BT), and toes-up rotations (RT)...
September 1998: Journal of Vestibular Research: Equilibrium & Orientation
S J Garland, T J Stevenson, T Ivanova
OBJECTIVE: To compare postural responses during standing associated with self-paced unilateral arm flexion exhibited by young and elderly healthy subjects and subjects with hemiplegia from stroke. DESIGN AND SETTING: Descriptive cross-sectional study in a laboratory setting. PATIENTS: Ten young, 10 elderly healthy subjects, and 12 volunteers with longstanding hemiparesis following stroke were tested. The hemiplegic group had good functional balance scores on the Berg Balance Scale (BBS)...
October 1997: Archives of Physical Medicine and Rehabilitation
T J Stevenson, S J Garland
OBJECTIVE: To examine the concurrent validity of the Berg Balance Scale (BBS) in subjects with hemiparesis after stroke by correlating functional balance performance on the BBS with laboratory measures of balance (center of pressure [CP] and electromyographic [EMG] activity of leg musculature during rapid arm flexion and during quiet stance). DESIGN: Concurrent validation study. Consistency of performance was determined through repeat measures obtained from 13 subjects...
July 1996: Archives of Physical Medicine and Rehabilitation
A G Brice, H V Forster, L G Pan, A Funahashi, M D Hoffman, C L Murphy, T F Lowry
We studied the role of spinal afferent pathways in the hyperpnea of electrically induced muscle contractions (ExE). The ventilatory (VE) and arterial CO2 partial pressure (PaCO2) responses were measured at rest and during two levels of ExE in awake human paraplegic subjects with clinically complete lesions of the spinal cord (range T4-T11). We hypothesized that if peripheral neural drive is critical to a normal ventilatory response, then ExE in the absence of intact pathways should cause a lower ventilatory response resulting in hypercapnia at the onset of ExE...
January 1988: Journal of Applied Physiology
W O Roberts, D L Elliot
A 28-yr-old, female marathon and "fitness" runner presented with leg swelling, fatigue, and loss of endurance. She was running an hour or more daily in addition to regular biking and swimming. She was an instructor in a fitness center. For 2 months prior to her leg swelling, she had increased fatigue and decreased exercise tolerance. She had been seen previously for a slow healing hamstring strain. She had not had a menstrual period for over 2 yr and had refused evaluation. She admitted to very low dietary intake, which she had always denied...
May 1991: Medicine and Science in Sports and Exercise
F R Noyes, O D Schipplein, T P Andriacchi, S R Saddemi, M Weise
Thirty-two patients with an ACL-deficient knee and lower limb varus alignment and 16 healthy controls were analyzed during level walking using a force-plate and optoelectronic system. The forces and moments of the lower limb and knee joint were measured and knee joint loads and ligament tensile forces were calculated using a mathematical model. The majority of patients (20 of 32) had an abnormally high adduction moment at the affected knee. The adduction moment showed a statistically significant correlation to high medial tibiofemoral compartment loads and high lateral soft tissue forces, but not to the degree of varus alignment on standing roentgenograms...
November 1992: American Journal of Sports Medicine
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