Upper limb movement analysis during gait in multiple sclerosis patients

PurposeGait disorders in multiple sclerosis (MS) are well studied; however, no previous study has described upper limb movements during gait. However, upper limb movements have an important role during locomotion and can be altered in MS patients due to direct MS lesions or mechanisms of compensation. The aim of this study was to describe the arm movements during gait in a population of MS patients with low disability compared with a healthy control group.MethodsIn this observational study we analyzed the arm movements during gait in 52 outpatients (mean age: 39.7 ± 9.6 years, female: 40%) with relapsing-remitting MS with low disability (mean EDSS: 2 ± 1) and 25 healthy age-matched controls using a 3-dimension gait analysis.ResultsMS patients walked slower, with increased mean elbow flexion and decreased amplitude of elbow flexion (ROM) compared to the control group, whereas shoulder and hand movements were similar to controls. These differences were not explained by age or disability.ConclusionUpper limb alterations in movement during gait in MS patients with low disability can be characterized by an increase in mean elbow flexion and a decrease in amplitude (ROM) for elbow flexion/extension. This upper limb movement pattern should be considered as a new component of gait disorders in MS and may reflect subtle motor deficits or the use of compensatory mechanisms.     

Proprioceptive impairments associated with knee osteoarthritis are not generalized to the ankle and elbow joints

The mechanisms for proprioceptive changes associated with knee osteoarthritis (OA) remain elusive. Observations of proprioceptive changes in both affected knees and other joints imply more generalized mechanisms for proprioceptive impairment. However, evidence for a generalized effect remains controversial. This study examined whether joint repositioning proprioceptive deficits are localized to the diseased joint (knee) or generalized across other joints (elbow and ankle) in people with knee OA. Thirty individuals with right knee OA (17 female, 66 ± 7 [mean ± SD] years) of moderate/severe radiographic disease severity and 30 healthy asymptomatic controls of comparable age (17 female, 65 ± 8 years) performed active joint repositioning tests of the knee, ankle and elbow in randomised order in supine. Participants with knee OA had a larger relative error for joint repositioning of the knee than the controls (OA: 2.7 ± 2.1°, control: 1.6 ± 1.7°, p = .03). Relative error did not differ between groups for the ankle (OA: 2.2 ± 2.5°, control: 1.9 ± 1.3°, p = .50) or elbow (OA: 2.5 ± 3.3°, control: 2.9 ± 2.8°, p = .58). These results are consistent with a mechanism for proprioceptive change that is localized to the knee joint. This could be mediated by problems with mechanoreceptors, processing/relay of somatosensory input to higher centers, or joint-specific interference with cognitive processes by pain.     

Different coordination and flexibility of the spine and pelvis during lateral bending between young and older adults

This study examined coordination of the spine and pelvis during lateral bending of the trunk in older adults. Thirty-four healthy subjects (17 young and 17 older adults) demonstrated lateral bending at a controlled speed while holding a bar at approximately 180 degrees of shoulder flexion. Kinematic data collection was completed on the thoracic spine, lumbar spine, and pelvis. The coupling angle was calculated to examine the thorax–lumbar, lumbar–pelvis, and thorax–pelvis coordination patterns. The older adults demonstrated a reduced range of motion (ROM) of the lumbar spine, while both groups revealed similar ROM in the thorax and in the pelvis. The coupling angle between the straightening and bending phases was different only for the older adults in the thorax–lumbar (23.4 ± 8.0 vs. −1.6 ± 4.4, p = 0.004) and the lumbar–pelvis (65.4 ± 7.2 vs. 86.1 ± 7.8, p = 0.001) coordination. However, there was no group difference in the thorax–pelvis coordination. These findings indicate that age-related changes in the lumbar region affect coordination patterns only during the bending phase. The older adults preserved a similar pattern of movement to the young adults during the straightening phase, but the coordination variability of the coupling angles was greater for the older adults than for the young adults. This movement pattern suggests that the older adults lacked consistent trunk control in an attempt to optimize lateral bending coordination.     

The influence of the human TMJ eminence inclination on predicted masticatory muscle forces

Aim of this paper was to investigate the change in masticatory muscle forces and temporomandibular joint (TMJ) reaction forces simulated by inverse dynamics when the steepness of the anterior fossa slope was varied. We used the model by de Zee et al. (2007) created in AnyBody™. The model was equipped with 24 musculotendon actuators. Mandibular movement was governed by the trajectory of the incisal point. The TMJ was modelled as a planar constraint canted 5° medially and the caudal inclination relative to the occlusal plane was varied from 10° to 70°. Our models showed that for the two simulated movements (empty chewing and unilateral clenching) the joint reaction forces were smallest for the eminence inclination of 30° and 40° and highest for 70°. The muscle forces were relatively insensitive to change of the eminence inclination for the angles between 20° and 50°. This did not hold for the pterygoid muscle, for which the muscle forces increased continually with increasing fossa inclination. For empty chewing the muscle force reached smaller values than for clenching. During clenching, the muscle forces changed by up to 200 N.     

Changes in muscular activity and lumbosacral kinematics in response to handling objects of unknown mass magnitude

The aim of this study was to evaluate the main and interaction effects of mass knowledge and mass magnitude on trunk muscular activity and lumbosacral kinematics. Eighteen participants performed symmetric box lifts of three different mass magnitudes (1.1 kg, 5 kg, 15 kg) under known and unknown mass knowledge conditions. Outcome measures were normalized peak electromyography of four trunk muscles in addition to three dimensional lumbosacral angles and acceleration. The results indicated that three out of four muscles exhibited significantly greater activity when handling unknown masses (p < .05). Meanwhile, only sagittal angular acceleration was significantly higher when handling unknown masses (115.6 ± 42.7°/s²) compared to known masses (109.3 ± 31.5°/s²). Similarly, the mass magnitude and mass knowledge interaction significantly impacted the same muscles along with the sagittal lumbosacral angle and angular acceleration (p < .05) with the greatest difference between knowledge conditions being consistently occurring under the 1.1 kg mass magnitude condition. Thus, under these conditions, it was concluded that mass magnitude has more impact than mass knowledge. However, handling objects of unknown mass magnitude could be hazardous, particularly when lifting light masses, in that they can increase mechanical burden on the lumbosacral spine due to increased muscular exertion and acceleration.     

Applying an active lumbopelvic control strategy during lumbar extension exercises: Effect on muscle recruitment patterns of the lumbopelvic region

ObjectiveExamine whether implementing an active lumbopelvic control strategy during high load prone lumbar extension exercises affects posterior extensor chain recruitment and lumbopelvic kinematics.MethodsThirteen healthy adults acquired an optimal active lumbopelvic control strategy during guided/home-based training sessions. During the experimental session electromyography was used to evaluate the activity of the posterior extensor chain muscles during high load trunk/bilateral leg extension exercises with/without application of the strategy. Video-analysis was used to evaluate thoracic/lumbar/hip angles.ResultsImplementing the active lumbopelvic control strategy decreased the lordotic angle during trunk (p = 0.045; −3.2°) and leg extension exercises (p = 0.019; −10°). The hip angle was solely affected during trunk extension (p < 0.001; +9.2°). The posterior extensor chain (i.e. mean of the relative activity of all muscles (%MVIC) was recruited to a higher extent (p = 0.026; +9%) during trunk extension exercises performed with active lumbopelvic control. Applying the strategy during leg extension exercises lead to less activity of longissimus thoracic (p = 0.015; −10.2%) and latissimus dorsi (p = 0.010; −4.4%), and increased gluteus maximus activity (p ≤ 0.001; +16.8%).ConclusionsWhen healthy people are taught/instructed to apply an active lumbopelvic control strategy, this will decrease the degree of lumbar (hyper)lordosis and this influences the recruitment patterns of trunk and hip extensors. Hence, the possible impact on predetermined training goals should be taken into account by trainers.     

The coupling between gaze behavior and opponent kinematics during anticipation of badminton shots

PurposeWe examined links between the kinematics of an opponent’s actions and the visual search behaviors of badminton players responding to those actions.MethodA kinematic analysis of international standard badminton players (n = 4) was undertaken as they completed a range of serves. Video of these players serving was used to create a life-size temporal occlusion test to measure anticipation responses. Expert (n = 8) and novice (n = 8) badminton players anticipated serve location while wearing an eye movement registration system.ResultsDuring the execution phase of the opponent’s movement, the kinematic analysis showed between-shot differences in distance traveled and peak acceleration at the shoulder, elbow, wrist and racket. Experts were more accurate at responding to the serves compared to novice players. Expert players fixated on the kinematic locations that were most discriminating between serve types more frequently and for a longer duration compared to novice players. Moreover, players were generally more accurate at responding to serves when they fixated vision upon the discriminating arm and racket kinematics.ConclusionsFindings extend previous literature by providing empirical evidence that expert athletes’ visual search behaviors and anticipatory responses are inextricably linked to the opponent action being observed.     

Biomechanical analysis of gait termination in 11–17 year old youth at preferred and fast walking speeds

In populations where walking and/or stopping can be difficult, such as in children with cerebral palsy, the ability to quickly stop walking may be beyond the child’s capabilities. Gait termination may be improved with physical therapy. However, without a greater understanding of the mechanical requirements of this skill, treatment planning is difficult. The purpose of this study was to understand how healthy children successfully terminate gait in one step when walking quickly, which can be challenging even for healthy children. Lower extremity kinematic and kinetic data were collected from 15 youth as they performed walking, planned, and unplanned stopping tasks. Each stopping task was performed as the subject walked at his/her preferred speed and a fast speed. The most significant changes in mechanics between speed conditions (preferred and fast) of the same stopping task were greater knee flexion angles (unplanned: +16.49 ± 0.54°, p = 0.00; planned: +15.75 ± 1.1°, p = 0.00) and knee extension moments (unplanned: +0.67 ± 0.02 N/kgm, p = 0.00; planned: +0.57 ± 0.23 N/kgm, p = 0.00) at faster speeds. The extra range of motion in the joints and extra muscle strength required to maintain the stopping position suggests that stretching and strengthening the muscles surrounding the joints of the lower extremity, particularly the knee, may be a useful intervention.     

Multi-body dynamic coupling mechanism for generating throwing arm velocity during baseball pitching

The purpose of this study was to identify the detailed mechanism how the maximum throwing arm endpoint velocity is determined by the muscular torques and non-muscular interactive torques from the perspective of the dynamic coupling among the trunk, thorax and throwing and non-throwing arm segments. The pitching movements of ten male collegiate baseball pitchers were measured by a three-dimensional motion capture system. Using the induced-segmental velocity analysis (IVA) developed in this study, the maximum fingertip velocity of the throwing arm (MFV) was decomposed into each contribution of the muscular torques, passive motion-dependent torques due to gyroscopic moment, Coriolis force and centrifugal force, and other interactive torque components. The results showed that MFV (31.6 ± 1.7 m/s) was mainly attributed to two different mechanisms. The first is the passive motion-dependent effect on increasing the angular velocities of three joints (thorax rotation, elbow extension and wrist flexion). The second is the muscular torque effect of the shoulder internal rotation (IR) torque on generating IR angular velocity. In particular, the centrifugal force-induced elbow extension motion, which was the greatest contributor among individual joint contributions, was caused primarily by the angular velocity-dependent forces associated with the humerus, thorax, and trunk rotations. Our study also found that a compensatory mechanism was achieved by the negative and positive contributions of the muscular torque components. The current IVA is helpful to understand how the rapid throwing arm movement is determined by the dynamic coupling mechanism.     

Effects of short-term fatigue on biomechanical and physiological aspects of double poling in high-level cross-country skiers

The study aim was to evaluate biomechanical and physiological alterations in double poling technique (DP) after a short-term fatiguing exercise. Eight high-level skiers performed a sub-maximal DP trial (20 km h⁻¹, 1°) before (PRE) and after (POST) a DP test to exhaustion while roller skiing on a treadmill. An integrated analysis of DP technique during PRE and POST included measurement of pole, joint, and centre of mass (COM) kinematics, poling forces, cycle timing, and metabolic parameters. Muscle fatigue in three upper-body muscles was assessed by calculating the Dimitrov’ fatigue index (FI_nms5) of specific electromyographic segments. FI_nms5 tended to increase in the latissimus dorsi and teres major muscles (P = 0.023 and P = 0.030, respectively) across consecutive DP cycles, as did blood lactate concentration (P = 0.001) and rating of perceived exertion (P = 0.005). The changes indicated a state of fatigue during POST and coincided with the reduction in poling force exertion capacity (P = 0.020). Pole, joint and COM kinematics did not differ between PRE and POST (P > 0.050), whereas recovery phase and cycle times were shorter at POST (P < 0.001 and P = 0.001, respectively). Short-term fatigue led to a reduction in poling force exertion capacity and cycle time in high-level skiers, without altering body and pole kinematics.     

Contralateral pelvic drop during gait increases knee adduction moments of asymptomatic individuals

PurposeThe current study purpose was to investigate the effects of contralateral pelvic drop gait on the magnitude of the knee adduction moment (KAM) within asymptomatic individuals.Methods15 participants walked on a dual belt instrumented treadmill while segment motions and ground reaction forces were recorded. Participants completed typical gait trials and pelvic drop gait trials. The net external KAM was calculated using inverse dynamics. Peak and impulse were identified. Frontal plane hip abduction/adduction and pelvic drop were determined. Correlations and paired t-tests were used for statistical hypothesis testing (alpha = 0.05).ResultsPeak hip adduction angle reached 4° (±6°) during pelvic drop trials compared to 0° (±6°) in the typical gait trials (p < 0.05) equating to 4° of pelvic drop. KAM impulse was higher in the pelvic drop trial (0.16 Nm s/kg ± 0.04) compared to the typical gait trial (0.13 Nm s/kg ± 0.05) (p < 0.001). Peak KAM was higher in the pelvic drop trial (0.55 Nm/kg ± 0.15) compared to the typical gait trial (0.40 Nm/kg ± 0.109) (p < 0.001). Correlations between change in KAM and change in hip adduction moment and pelvic drop were r > 0.80 (p < 0.001).ConclusionPelvic drop gait increased KAM peak and impulse. Results have implications for understanding relationships between frontal plane hip movement and the knee adduction moment during gait.     

Lower limb mechanical asymmetry during repeated treadmill sprints

Stride mechanical imbalances between the lower limbs may be detrimental to performance and/or increase injury risks. This study describes the time course and magnitude of asymmetries in running mechanical variables during repeated treadmill sprints and examines whether inter-limb differences in sprinting mechanics increase with fatigue. Thirteen non-injured male athletes performed five 5-s sprints with 25-s recovery on an instrumented treadmill, allowing the continuous (step-by-step) measurement of running kinetics/kinematics and spring-mass characteristics calculation. For each variable, bilateral leg asymmetry (BLA%) between the left and the right leg was defined as: {[(high value − low value)/low value] × 100}. BLA% for propulsive power and horizontal forces averaged ∼12–13%, while lower values occurred for step-averaged values of running velocity, resultant and vertical forces (all ∼4%). For all sprints, kinematic BLA% ranged from 1.6 ± 1.0% (swing time) to 9.0 ± 5.3% (aerial time). BLA% for vertical and leg stiffness was 6.4 ± 4.9% and 7.6 ± 3.6%, respectively. While distance covered decreased across repetitions (P < 0.05), there was no significant interaction between sprint repetitions and leg side for any of the mechanical variables studied (all P > 0.05). Although inter-limb differences were observed for many running kinetics/kinematics and spring-mass characteristics during repeated treadmill sprints, the lack of interaction between sprint repetitions and leg side suggests that lower limbs fatigued at a similar rate.     

Multi-segmental thoracic spine kinematics measured dynamically in the young and elderly during flexion

In contrast to the cervical and lumbar region, the normal kinematics of the thoracic spine have not been thoroughly investigated. The aim of this study was to characterize normal multi-segmental continuous motion of the whole thoracolumbar spine, during a flexion maneuver, in young and elderly subjects. Forty-two healthy volunteers were analyzed: 21 young (age = 27.00 ± 3.96) and 21 elderly (age = 70.1 ± 3.85). Spinal motion was recorded with a motion-capture system and analyzed using a 3rd order polynomial function to approximate spinal curvature throughout the motion sequence. The average motion profiles of the two age groups were characterized. Flexion timing of the thoracic region of the spine, as compared to the lumbar spine and hips, was found to be different in the two age groups (p = 0.011): a delayed/sequential motion type was observed in most of the young, whereas mostly a simultaneous motion pattern was observed in the elderly subjects. A similar trend was observed in flexion of the lower thoracic segments (p = 0.017). Differences between age groups were also found for regional and segmental displacements and velocities. The reported characterization of the thoracic spine kinematics may in the future support identification of abnormal movement or be used to improve biomechanical models of the spine.     

Motor imagery ability and internal representation of movement in children with probable developmental coordination disorder

It has been hypothesised that deficits in the functioning of the mirror neuron system (MNS) and internal modelling may contribute to the motor impairments associated with DCD. These processes can be explored behaviourally through motor imagery paradigms. Motor imagery proficiency of children with and without probable DCD (pDCD) was examined using a complex hand rotation task to explore whether motor imagery strategies could be used during more complex tasks. Forty-four boys aged 7–13 years participated, 22 with pDCD (mean = 9.90 years ± 1.57) and 22 controls (mean = 9.68 years ± 1.53). Participants completed the task twice: with and without motor imagery instructions. Stimuli were presented in two rotational axes – palm/back, and eight 45° rotational steps. Both groups showed evidence of following the biomechanical and postural constraints of actual movements. Responses of children with pDCD were slower and less accurate than controls, with group differences increasing alongside task complexity. A greater impact of biomechanical constraints for accuracy was observed in the DCD group. The response characteristics of children with pDCD likely reflects a reduced capacity to mentally manipulate a body schema and reduced visuo-motor processing capabilities. Behaviourally, these processes are linked to MNS and internal modelling function, suggesting deficits in these systems may contribute to the movement difficulties characteristic of DCD.     

Concussion is associated with altered preparatory postural adjustments during gait initiation

Gait initiation is a useful surrogate measure of supraspinal motor control mechanisms but has never been evaluated in a cohort following concussion. The aim of this study was to quantify the preparatory postural adjustments (PPAs) of gait initiation (GI) in fifteen concussion patients (4 females, 11 males) in comparison to a group of fifteen age- and sex-matched controls. All participants completed variants of the GI task where their dominant and non-dominant limbs as the ‘stepping’ and ‘support’ limbs. Task performance was quantified using the centre of pressure (COP) trajectory of each foot (computed from a force plate) and a surrogate of the centre of mass (COM) trajectory (estimated from an inertial measurement unit placed on the sacrum).Concussed patients exhibited decreased COP excursion on their dominant foot, both when it was the stepping limb (sagittal plane: 9.71 mm [95% CI: 8.14–11.27 mm] vs 14.9 mm [95% CI: 12.31–17.49 mm]; frontal plane: 36.95 mm [95% CI: 30.87–43.03 mm] vs 54.24 mm [95% CI: 46.99–61.50 mm]) and when it was the support limb (sagittal plane: 10.43 mm [95% CI: 8.73–12.13 mm] vs 18.13 mm [95% CI: 14.92–21.35 mm]; frontal plane: 66.51 mm [95% CI: 60.45–72.57 mm] vs 88.43 mm [95% CI: 78.53–98.32 mm]). This was reflected in the trajectory of the COM, wherein concussion patients exhibited lower posterior displacement (19.67 mm [95% CI: 19.65 mm–19.7 mm]) compared with controls (23.62 mm [95% CI: 23.6–23.64]). On this basis, we conclude that individuals with concussion display deficits during a GI task which are potentially indicative of supraspinal impairments in motor control.     

Various shrug exercises can change scapular kinematics and scapular rotator muscle activities in subjects with scapular downward rotation syndrome

Scapular dyskinesis, characterized by scapular downward rotation syndrome (SDRS) affects scapula-humeral rhythm and results in shoulder dysfunction. Previous study has led to the recommendation of standard shrug exercise to contend with SDRS and strengthen the upper trapezius (UT) muscle. However, few researchers have examined which shrug exercise is most effective. The aim of this research was to compare scapular kinematic changes and scapular rotator muscles activity across three different shrug exercises in SDRS. The amounts of scapular downward rotation were measured by a caliper and the scapular upward rotation angle was measured using two digital inclinometers. Surface electromyography was used to measure EMG amplitude from the UT, lower trapezius (LT), serratus anterior (SA), and levator scapula (LS). Seventeen subjects with SDRS were recruited for this study. The subjects performed three shrug exercises with 30° shoulder abduction (preferred shrug, frontal shrug, and stabilization shrug). The stabilization shrug showed a significantly greater scapular upward rotation angle compared with the preferred shrug (P = 0.004) and frontal shrug (P = 0.006). The UT activity was significantly greater in the frontal shrug than in the preferred shrug (P = 0.002). The UT/LS muscle activity ratio was also significantly greater in the frontal shrug than in the preferred shrug (P = 0.004). The stabilization shrug should be preferred to enhance the upward rotation angle. In addition, the frontal shrug can be used as an effective method to increase UT activity and to decrease LS activity in SDRS.     

External focus and autonomy support: Two important factors in motor learning have additive benefits

We examined whether the combination of two factors that have consistently been found to enhance motor learning – an external focus (EF) of attention and autonomy support (AS) – would produce additive benefits. Participants practiced throwing with their non-dominant arm. In a 2 × 2 design, they were or were not asked to focus externally (i.e., on the target), and were or were not given a choice (autonomy support). The latter involved choosing 2 5-trials blocks during practice on which they used their dominant arm. All four groups – EF/AS, EF, AS, and C (control) – completed a practice phase consisting of 60 trials. The distance to the target (bull’s eye) was 7.5 m. One day later, participants performed retention (same target distance) and transfer tests (8.5 m). Both external focus instructions and autonomy support enhanced retention and transfer performance. Importantly, the combination of these factors resulted in additive learning advantages. The EF/AS group showed the greatest throwing accuracy, and the EF and AS groups outperformed the C group. In addition, self-efficacy measured after practice and before retention and transfer was increased by both factors. Thus, promoting an external focus of attention and supporting learners’ need for autonomy seem to independently influence learning.     

Technique determinants of knee joint loads during cutting in female soccer players

The aim of this study was to investigate the relationships between technique characteristics and knee abduction moments during 90° cuts. A cross sectional design involving 26 elite and sub-elite female soccer players (mean ± SD; age: 21 ± 3.2 years, height: 1.68 ± 0.07 m, and mass: 59.1 ± 6.8 kg) was used to explore relationships between pre-determined technical factors on knee abduction moments during cutting. Three dimensional motion analyses of 90° cuts on the right leg were performed using ‘Qualisys Pro Reflex’ infrared cameras (240 Hz). Ground reaction forces were collected from two AMTI force platforms (1200 Hz) embedded into the running track to examine 2nd last and last footfalls. Pearson’s correlation coefficients, co-efficients of determination and hierarchical multiple regression were used to explore relationships between a range of technique parameters and peak knee abduction moments. Significance was set at p < .05. Hierarchical multiple regression revealed that initial knee abduction angle, lateral leg plant distance and initial lateral trunk lean could explain 67% (62% adjusted) of the variation in peak knee abduction moments (F_(1,22) = 8.869, p = .007). These findings reveal potential modifiable technical factors to lower peak knee abduction moments during cutting.