Joint Moments Of Force Research Articles

Training Benefits and Injury Risks of Standing Yoga Applied in Musculoskeletal Problems: Lower Limb Biomechanical Analysis.

Standing yoga poses strengthen a person’s legs and helps to achieve the goal of musculoskeletal rehabilitation, but inadequate exercise planning can cause injuries. This study investigated changes in the electromyogram and joint moments of force (JMOFs) of lower extremities during common standing yoga poses in order to explore the feasibility and possible injury risk in dealing with musculoskeletal problems. Eleven yoga instructors were recruited to execute five yoga poses (Chair, Tree, Warrior 1, 2, and 3). The results revealed significant differences in hip, knee, and ankle JMOFs and varying degrees of muscle activation among the poses. Among these poses, rectus femoris muscle activation during the Chair pose was the highest, Warrior 2 produced the highest muscle activation in the vastus lateralis of the front limb, while Warrior 1 had the highest muscle activation in the vastus medialis of the back limb. Therefore, all three poses can possibly be suggested as a therapeutic intervention for quadriceps strengthening. Warrior 1 was possibly suggested as a therapeutic intervention in order to reduce excessive lateral overload of the patella, but the possible adverse effects of Warrior 2 with the highest knee adductor JMOF in the back limb could raise joint reaction forces across the medial condyles. In single-leg balance postures, Warrior 3 had unique training effects on the hamstring, and is therefore suggested as a part of hamstring rehabilitation exercises. The Tree pose induced low lower-extremity JMOFs and a low level of thigh muscle activations when it was performed by senior instructors with excellent balance control; however, for yoga beginners with insufficient stability, it will be a useful training mode for strengthening the muscles that help to keep one upright. This study quantified the physical demands of yoga poses using biomechanical data and elucidated the structures and principles underlying each yoga movement. This is crucial for yoga practitioners.

Test-Retest Reliability of a 6DoF Marker Set for Gait Analysis in Cerebral Palsy Children

Background: Cerebral palsy (CP) is a complex pathology that describes a group of motor disorders with different presentations and functional levels. Three-dimensional gait analysis is widely used in the assessment of CP children to assist in clinical decision making. Thus, it is crucial to assess the repeatability of gait measurements to evaluate the progress of the rehabilitation process. The purpose of the study is to evaluate test-retest reliability of a six-degree-of-freedom (6DoF) marker set in key points of gait kinematics, kinetics, and time-distance parameters in children with CP. Methods: trials were performed on two different days within a period of 7.5 ± 1.4 day. Motion capture data was collected with 14 infrared, high-speed cameras at a frequency rate of 100 Hz, synchronized in time and space with two force plates. Intraclass correlation coefficients considering the two-way mixed model, and absolute agreement (ICC[A,k]) were calculated for anthropometric, time–distance, kinematic and kinetic parameters of both lower limbs. Results: the majority of gait parameters demonstrated a good ICC, and the lowest values were in the kinematic variables. Conclusions: this study indicates wide-ranging reliability values for lower limb joint angles and joint moments of force during gait, especially for frontal and transverse planes. Although the use of a 6DoF-CAST in CP children was shown to be a feasible method, the gait variation that can be observed between sessions in CP children seems to be related not only to the extrinsic factors but also to their different gait patterns and affected sides.

The biomechanical demands of standing yoga poses in seniors: The Yoga empowers seniors study (YESS)

BackgroundThe number of older adults participating in yoga has increased dramatically in recent years; yet, the physical demands associated with yoga performance have not been reported. The primary aim of the Yoga Empowers Seniors Study (YESS) was to use biomechanical methods to quantify the physical demands associated with the performance of 7 commonly-practiced standing yoga poses in older adults.Methods20 ambulatory older adults (70.7 + − 3.8 yrs) attended 2 weekly 60-minute Hatha yoga classes for 32 weeks. The lower-extremity net joint moments of force (JMOFs), were obtained during the performance of the following poses: Chair, Wall Plank, Tree, Warrior II, Side Stretch, Crescent, and One-Legged Balance. Repeated-measure ANOVA and Tukey’s post-hoc tests were used to identify differences in JMOFs among the poses. Electromyographic analysis was used to support the JMOF findings.ResultsThere was a significant main effect for pose, at the ankle, knee and hip, in the frontal and sagittal planes (p = 0.00 – 0.03). The Crescent, Chair, Warrior II, and One-legged Balance poses generated the greatest average support moments. Side Stretch generated the greatest average hip extensor and knee flexor JMOFs. Crescent placed the highest demands on the hip flexors and knee extensors. All of the poses produced ankle plantar-flexor JMOFs. In the frontal plane, the Tree generated the greatest average hip and knee abductor JMOFs; whereas Warrior II generated the greatest average hip and knee adductor JMOFs. Warrior II and One-legged Balance induced the largest average ankle evertor and invertor JMOFs, respectively. The electromyographic findings were consistent with the JMOF results.ConclusionsMusculoskeletal demand varied significantly across the different poses. These findings may be used to guide the design of evidence-based yoga interventions that address individual-specific training and rehabilitation goals in seniors.Clinical trial registrationThis study is registered with NIH Clinicaltrials.gov #NCT 01411059

Physical Demand Profiles of Hatha Yoga Postures Performed by Older Adults

Understanding the physical demands placed upon the musculoskeletal system by individual postures may allow experienced instructors and therapists to develop safe and effective yoga programs which reduce undesirable side effects. Thus, we used biomechanical methods to quantify the lower extremity joint angles, joint moments of force, and muscle activities of 21 Hatha yoga postures, commonly used in senior yoga programs. Twenty older adults, 70.7 years ± 3.8 years, participated in a 32-wk yoga class (2 d/wk) where they learned introductory and intermediate postures (asanas). They then performed the asanas in a motion analysis laboratory. Kinematic, kinetic, and electromyographic data was collected over three seconds while the participants held the poses statically. Profiles illustrating the postures and including the biomechanical data were then generated for each asana. Our findings demonstrated that Hatha yoga postures engendered a range of appreciable joint angles, JMOFs, and muscle activities about the ankle, knee, and hip, and that demands associated with some postures and posture modifications were not always intuitive. They also demonstrated that all of the postures elicited appreciable rectus abdominis activity, which was up to 70% of that induced during walking.

The effect of prolonged cycling on pedal forces

The aim of this study was to determine whether cyclists modify the pattern of force application to become more effective during a prolonged ride to exhaustion. Twelve competitive male cyclists completed a steady-rate exercise ride to exhaustion at 80% of their maximum power output at 90 rev · min−1 on a cycle ergometer. Pedal force, pedal and crank angle data were collected from an instrumented bicycle for three pedalling cycles at the end of the first and final minutes of the exercise test with simultaneous video recording of the lower limbs. Kinematic and force data were combined to compute hip, knee and ankle joint moments. There were changes in the pattern of force application, joint kinematics and joint moments of force. Comparison of the first minute and the final minute ride revealed significantly increased peak effective force (340±65.0 and 377±74.8 N for the first and final minute, respectively; F 1,11=7.44, P= 0.02), increased positive (28.4±4.5 and 30.5±4.8 N · s for the first and final minute, respectively; F 1,11=7.80, P= 0.02) and negative angular impulses (−1.5±1.6 and −2.4±1.5 N · s for the first and final minute, respectively; F 1,11=4.50, P= 0.06). Contrary to our initial assumptions, it would appear that riders became less effective during the recovery phase, which increased the demand for forces during the propulsive phase. Training the pattern of force application to improve effectiveness may be a useful strategy to prolong an endurance ride.

Characteristics of Gait in Hemiplegia

The following review examines the walking patterns of patients who have hemiplegia, primarily as a result of a stroke. Attention is given to the changes in the distance and temporal factors of walking, phasic patterns and joint ranges of motion throughout the walking cycle, the ground reaction forces, joint moments of force, joint powers, energy expenditure, and muscle activation patterns. The effect of orthotic intervention on these walking parameters is also addressed. A frequently cited issue regarding the gait patterns of these patients was that their walking patterns exhibit significant deviations from normal healthy individuals. Although hemiplegia is primarily associated with unilateral motor involvement, changes in almost all of the parameters used to assess walking were evident on both the involved and uninvolved sides of the body. Last, although hemiplegia appears to reflect a single diagnostic category, there is large interindividual variability in the patterns of gait deviations, which suggests that the management and treatment of these patients need to address the unique deficits of the individual.

An inverse dynamics model for the analysis, reconstruction and prediction of bipedal walking

Walking is a constrained movement which may best be observed during the double stance phase when both feet contact the floor. When analyzing a measured movement with an inverse dynamics model, a violation of these constrains will always occur due to measuring errors and deviations of the segments model from reality, leading to inconsistent results. Consistency is obtained by implementing the constraints into the model. This makes it possible to combine the inverse dynamics model with optimization techniques in order to predict walking patterns or to reconstruct non-measured rotations when only a part of the three-dimensional joint rotations is measured. In this paper the outlines of the extended inverse dynamics method are presented, the constraints which define walking are defined and the optimization procedure is described. The model is applied to analyze a normal walking pattern of which only the hip, knee and ankle flexions/extensions are measured. This input movement is reconstructed to a kinematically and dynamically consistent three-dimensional movement, and the joint forces (including the ground reaction forces) and joint moments of force, needed to bring about this movement are estimated.

Joint moments of force and quadriceps muscle activity during squatting exercise

The relationship between hip and knee joint load and quadriceps muscle activity during squatting exercise to different depths was studied. Eight young national class Olympic weightlifters performed squatting exercise to 4 different knee flexion angles; 45°, 90°, parallel and deep squats. They held a barbell across their shoulders with a weight of 65% of their one‐repetition maximum. The loading moments of force about the hip and knee joints were calculated using a semidynamic method. Video was used for motion recording and electromyograhy for recording activity from die vastus lateralis, rectus femoris and biceps femoris muscles. The loading moment on the hip joint increased significantly from the 90° squat to the parallel, but there was no difference between the parallel and the deep. For the knee joint, there was no difference between the 45°, 90° and parallel, but for the deep squat the loading moment increased significantly. The muscular activity generally increased with increasing squatting depth, but mere were only minor insignificant differences between the parallel and the deep squats. We conclude that knee joint load can be limited by doing parallel instead of deep squats and that this will not decrease quadriceps muscle activity. To limit hip moment, the squat should not be deeper than 90°.

Effects of a functional knee brace on the biomechanics of running

The purpose of the study was to assess the biomechanical effects of a functional knee brace on joint moments of force and joint powers in the lower extremity during the stance phase of running in subjects with a previous ACL injury. Sagittal-plane film records and ground reaction force data were obtained from five previously injured subjects running with and without a functional knee brace and from five healthy subjects running without the brace. Inverse dynamics were performed on these data to obtain the moments of force and joint powers. The angular impulse in the extensor direction was assessed from each moment of force curve, and the work performed during selected portions of the stance phase was assessed from the joint power curves. ANOVA techniques on these variables indicated no significant differences between the brace and no-brace conditions in the previously injured subjects. In comparison with the healthy runners, the previously injured subjects had, on average, 49% and 32% greater extensor angular impulse about the hip and ankle (both P less than 0.05). In contrast, the healthy runners had, on average, 233% greater (P less than 0.05) extensor angular impulse about the knee. The corresponding negative and positive work performed at the knee were 321% and 191% larger (both P less than 0.05) in the healthy runners. The reduction in the extensor moment of force about the knee and the increase in the moments of force about the hip and ankle in the previously injured subjects reduced the stresses on the ACL and tibia while at the same time enabling them to run at the required speed.

The Organization of Stepping in Patients with Parkinson’s Disease: Bradykinesia or Discoordination?

The purpose of this experiment was to quantify and analyse multijoint coordination of patients with Parkinson's disease (N = 5) and control subjects (N = 5) during forward and backward stepping motions executed at different cadences. Coordinates of reflective markers placed on the shoulder, hip, knee, ankle and metatarsal joints were recorded in the sagittal plane using a video motion analysis system. Kinematic and kinetic analyses provided angular displacements and velocities as well as joint moments of force and powers. Results suggest the presence of two types of discoordination: one type is velocity-dependent, hence related to bradykinesia, whereas the other type appears to reflect qualitatively different coordination patterns.

Biomechanical Walking Pattern Changes in the Fit and Healthy Elderly

A descriptive study of the biomechanical variables of the walking patterns of the fit and healthy elderly compared with those of young adults revealed several significant differences. The walking patterns of 15 elderly subjects, selected for their active life style and screened for any gait- or balance-related pathological conditions, were analyzed. Kinematic and kinetic data for a minimum of 10 repeat walking trials were collected using a video digitizing system and a force platform. Basic kinematic analyses and an inverse dynamics model yielded data based on the following variables: temporal and cadence measures, heal and toe trajectories, joint kinematics, joint moments of force, and joint mechanical power generation and absorption. Significant differences between these elderly subjects and a database of young adults revealed the following: the same cadence but a shorter step length, an increased double-support stance period, decreased push-off power, a more flat-footed landing, and a reduction in their "index of dynamic balance." All of these differences, except reduction in index of dynamic balance, indicate adaptation by the elderly toward a safer, more stable gait pattern. The reduction in index of dynamic balance suggests deterioration in the efficiency of the balance control system during gait. Because of these significant differences attributable to age alone, it is apparent that a separate gait database is needed in order to pinpoint falling disorders of the elderly.

Intrasubject variability of lower extremity joint moments of force during the stance phase of running

Intrasubject variability (ISV) of lower extremity joint moments of force (JMF) during the stance phase of running was evaluated. ISV was identified over four time periods: within session (C1), within day (C2), between day (C3) and between week (C4). Six, male runners performed 25 trials on each of 4 sessions from which 10 were randomly selected per session for analysis. Coefficients of variation (CV) and a single subject statistical procedure were used to quantify ISV. Average CVs of 11, 51, 16 and 11% were observed for support, hip, knee and ankle JMFs with larger values in C3 and C4. Statistical results identified 19, 29 and 46% of the comparisons as significant over periods C2–C4, indicating that ISV increased with the time between sessions. The combined results suggested that two test sessions, at least one day apart, provide an accurate assessment of an individual's JMF patterns.

Intrasubject variability in lower extremity joint moments of force during the support phase of running

Intrasubject variability in lower extremity joint moments of force during the support phase of running

The application of biomechanical motion analysis to aspects of green monkey (Cercopithecus a. sabaeus) locomotion.

A cinematographic method of biomechanical motion analysis is presented which permits the determination of body segment forces and joint moments of force, and thereby dominant muscle action. An analysis of the horizontal leap of Cercopithecus is used as an example of the utility of this approach in the area of functional morphology. Kinematic and kinetic data are presented and discussed in terms of the biomechanical requirements of this form of locomotion. The importance of a consideration of inertial as well as gravitational forces in an analysis of positional behavior involving body motion is stressed.