Sex differences in the kinematics and kinetics of the foot and plantar aponeurosis during drop-jump.

Plantar fasciitis is one of the most common musculoskeletal injuries in runners and jumpers, with a higher incidence in females. However, mechanisms underlying sex-associated differences in its incidence remain unclear. This study investigated the possible differences in landing and jumping kinematics and kinetics of the foot between sexes during drop-jump activities. Twenty-six participants, including 13 males and 13 females, performed drop-jumps from a platform onto force plates. Nineteen trials including ten males and nine females were selected for inverse dynamics analysis. The patterns of stretch and tensile force generated by the plantar aponeurosis (PA) were estimated using a multi-segment foot model incorporating the PA. Our results demonstrated that dorsiflexion, angular velocity, and normalized plantarflexion moment of the midtarsal joint right after the heel landed on the floor were significantly larger in females than in males. Consequently, the PA strain rate and tensile stress tended to be larger in females than in males. Such differences in the kinematics and kinetics of the foot and the PA between sexes could potentially lead to a higher prevalence of foot injuries such as plantar fasciitis in females.

Muscle co-activation in the elderly contributes to control of hip and knee joint torque and endpoint force.

We investigated the coordinated activity patterns of muscles based on cosine tuning in the elderly during an isometric force exertion task. We also clarified whether these coordinated activity patterns contribute to the control of hip and knee joint torque and endpoint force as co-activation. Preferred direction (PD) of activity for each muscle in 10 young and 8 older males was calculated from the lower limb muscle activity during isometric force exertion task in various directions. The covariance of endpoint force (η) was calculated from the exerted force data using a force sensor. Relationship between PD and η was used to examine the effect of muscle co-activation on the control of endpoint force. Co-activation between rectus femoris and semitendinosus/biceps femoris increased with changes in muscle PD. Additionally, the η values were significantly low, suggesting that co-activation of multiple muscles may contribute to endpoint force exertion. The mechanism for cooperative muscle activity is determined by the cosine tuning of the PD of each muscle, which affects the generation of hip and knee joint torque and endpoint force exertion. Co-activation of each muscle's PD changes with age, causing increased muscle co-activation to control torque and force. We demonstrated that co-activation in the elderly is a stabilizer of unsteady joints and a muscle control strategy for cooperative muscle activity.

Movement-synchronized cerebellum rhythm coordinates multi-joint movements in young and elderly adults.

Rhythmic limb multi-joint movement like locomotion is controlled by intralimb coordination. Intralimb coordination changes entail immediate alterations in movement patterns and be related with cerebellum function. Synchronized cerebellum activity has known to modulate the frequency of walking, but not known the effect of only intralimb coordination. The purpose of this study was to reveal the effect of synchronized and unsynchronized cerebellum activity on the coordination of multi-joint movements of the unilateral leg in young and elderly people. To achieve our purpose, we applied synchronized and unsynchronized cerebellum transcranial alternating current stimulation during cyclic unilateral multi-joint movement by visual tracking task. The results showed that the reduction in comprehensive synchrony between targets and movements through trials had no significant differences under all stimulus conditions in young and elderly people. However, the reduction in variation of synchronization through trials was significantly smaller under the synchronized transcranial alternating current stimulation condition in both young and elderly groups. Variation of synchronization was remarkably reduced under the synchronized transcranial alternating current stimulation condition for the elderly group. This study showed that movement-synchronized cerebellum activity contributes to reducing fluctuations in movement synchrony by coordinating unilateral multi-joint movements. Moreover, this reduction was remarkable in the elderly group.

Compensatory relationship of mechanical energy in paretic limb during sit-to-stand motion of stroke survivors.

The sit-to-stand motion is a prerequisite for walking and is therefore frequently performed in daily life. Diseases such as stroke often make performing it challenging. Even the stroke survivors who can stand up, the number of sit-to-stand motions they perform each day is lower than that of healthy adults. The inability of stroke survivors to stand up many times might be due to uneven distribution of mechanical energy expenditure across body parts. However, it was unclear in which body part this mechanical energy expenditure was concentrated, i.e., whether it was due to co-contraction of the paretic limb or compensation by the sound limb. Thus, this study aims to identify which body parts are responsible for mechanical energy expenditure in stroke survivors. Ten stroke survivors and ten healthy adults performed sit-to-stand motion recorded using motion capture cameras. We created a 3-D human model and calculated the mechanical energy expenditure for each joint and segment. The stroke survivors expended more mechanical energy in the affected hip and waist in contrast to the affected knee. Notably, a compensatory relationship for mechanical energy expenditure was observed between adjacent joints on the affected side and not between the affected and sound limbs. This is because stroke survivors may have achieved the sit-to-stand motion by compensating for the distal part with the less impaired proximal part. In addition, the more severe the movement disorders, the more mechanical energy must be expended in the paretic hip to achieve the sit-to-stand motion. These results could contribute to fundamental knowledge about more comfortable daily living in stroke survivors.

Novel Multi-Segment Foot Model Incorporating Plantar Aponeurosis for Detailed Kinematic and Kinetic Analyses of the Foot With Application to Gait Studies.

Kinetic multi-segment foot models have been proposed to evaluate the forces and moments generated in the foot during walking based on inverse dynamics calculations. However, these models did not consider the plantar aponeurosis (PA) despite its potential importance in generation of the ground reaction forces and storage and release of mechanical energy. This study aimed to develop a novel multi-segment foot model incorporating the PA to better elucidate foot kinetics. The foot model comprised three segments: the phalanx, forefoot, and hindfoot. The PA was modeled using five linear springs connecting the origins and the insertions via intermediate points. To demonstrate the efficacy of the foot model, an inverse dynamic analysis of human gait was performed and how the inclusion of the PA model altered the estimated joint moments was examined. Ten healthy men walked along a walkway with two force plates placed in series close together. The attempts in which the participant placed his fore- and hindfoot on the front and rear force plates, respectively, were selected for inverse dynamic analysis. The stiffness and the natural length of each PA spring remain largely uncertain. Therefore, a sensitivity analysis was conducted to evaluate how the estimated joint moments were altered by the changes in the two parameters within a range reported by previous studies. The present model incorporating the PA predicted that 13%-45% of plantarflexion in the metatarsophalangeal (MTP) joint and 8%-29% of plantarflexion in the midtarsal joints were generated by the PA at the time of push-off during walking. The midtarsal joint generated positive work, whereas the MTP joint generated negative work in the late stance phase. The positive and negative work done by the two joints decreased, indicating that the PA contributed towards transfer of the energy absorbed at the MTP joint to generate positive work at the midtarsal joint during walking. Although validation is limited due to the difficulty associated with direct measurement of the PA force in vivo, the proposed novel foot model may serve as a useful tool to clarify the function and mechanical effects of the PA and the foot during dynamic movements.

Facial onset sensory and motor neuropathy in a pain clinic outpatient: a case report.

BACKGROUND: Facial onset sensory and motor neuropathy is a very rare sensorimotor disorder characterized by facial onset and gradual progression, with approximately 100 cases reported worldwide in 2020. We report on our experience with a facial onset sensory and motor neuropathy case in our outpatient pain clinic. CASE PRESENTATION: A 71-year-old Japanese man with a previous diagnosis of trigeminal nerve palsy complained of facial paresthesia, cervical pain, and arm numbness. Cervical facet arthropathy was diagnosed initially, but neither pharmacotherapy nor nerve blocking alleviated his symptoms. We suspected bulbar palsy based on the presence of tongue fasciculation, which prompted referral to a neurologist. Based on a series of neurological examinations, facial onset sensory and motor neuropathy was ultimately diagnosed. CONCLUSIONS: Pain clinicians must be mindful of rare diseases such as facial onset sensory and motor neuropathy; if they are unable to make a diagnosis, they should consult with other competent specialists.

Evaluation of the Validity, Reliability, and Kinematic Characteristics of Multi-Segment Foot Models in Motion Capture.

This study aimed to evaluate the validity and reliability of our new multi-segment foot model by measuring a dummy foot, and examine the kinematic characteristics of our new multi-segment foot model by measuring the living body. Using our new model and the Rizzoli model, we conducted two experiments with a dummy foot that was moved within a range from -90 to 90 degrees in all planes; for the living body, 24 participants performed calf raises, gait, and drop jumps. Most three-dimensional (3D) rotation angles calculated according to our new models were strongly positively correlated with true values (r > 0.8, p < 0.01). Most 3D rotation angles had fixed biases; however, most of them were in the range of the limits of agreement. Temporal patterns of foot motion, such as those in the Rizzoli model, were observed in our new model during all dynamic tasks. We concluded that our new multi-segment foot model was valid for motion analysis and was useful for analyzing the foot motion using 3D motion capture during dynamic tasks.

Analysis of Relationships between Spinal Deformity and Walking Ability in Parkinson's Disease Patients.

INTRODUCTION: This study aimed to determine impacts on walking ability of spinal deformity and imbalance as distinct from movement disorders in Parkinson's disease (PD). METHODS: Thirty-two patients (15 males, 17 females; mean age 72.5 years) were analyzed. Three, thirteen, eleven, and five were at Hoehn-Yahr stages I, II, III, and IV, respectively. In addition to various spinal imbalance and deformity classifications the following were assessed: Cobb angle (CA) for scoliosis, thoracic kyphosis (TK) at T2-12, thoracolumbar kyphosis(TLK) at T12-L2, lumbar lordosis(LL) at L1-S1, pelvic tilt(PT), pelvic incidence(PI), and sagittal vertical axis(SVA). The Timed Up and Go (TUG) test was used to measure walking ability. Patients were evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS) part III, and bone mineral density (BMD) scans. RESULTS: Nineteen patients (59%) had spinal deformity and imbalance within the following classifications: thoracic scoliosis, 1; thoracic kyphosis, 2; lumbar scoliosis, 15; Pisa syndrome, 3; camptocormia, 2. Mean values were 20.0° CA for scoliosis, 42.3° TK, 14.8° TLK, 26.7° LL, 20.8° PT, 48.8° PI, and 66.4 mm SVA. The mean TUG score was 13.9s. The UPDRS III mean was 36.6±24.5 points. Mean BMD was 0.856 g/cm2 at lumbar L2-4 and 0.585 g/cm2 at the femoral neck. UPDRS part III (P<0.001), LL (P<0.05), and femoral neck BMD (P<0.05) significantly correlated to TUG test results. CONCLUSIONS: Distinct from the movement disorders of PD (UPDRS III), loss of normal LL and loss of BMD at the femoral neck were shown to be correlated with diminished walking ability (TUG test) in PD patients. When UPDRS improved in response to L-dopa, walking ability improved. In addition to any PD-specific interventions that contribute to the maintenance of ambulation, interventions specific to the restoration of LL, as well as early treatment for osteoporosis may positively affect HRQOL in PD.

Adaptive changes in foot placement for split-belt treadmill walking in individuals with stroke.

BACKGROUND: Adaptation to split-belt treadmill walking differs between individual stroke survivors. Many discussions only address spatiotemporal parameters that are related to movement, and the changes in interlimb spatiotemporal parameters as a consequence of adaptation are poorly understood. OBJECTIVES: To investigate symmetry of the center of pressure (CoP) position relative to the center of mass (CoM), and ascertain whether this can be used to identify differences in adaptation of interlimb spatiotemporal parameters among stroke survivors during split-belt walking. METHODS: Twenty-two chronic post-stroke patients and nine elderly controls walked in tied- then split-belt (2:1 ratio of fast:slow) conditions. Spatiotemporal parameters were compared within groups to assess symmetry of the CoM-CoP angle at foot contact. RESULTS: Asymmetry of the CoM-CoP angle was associated with asymmetry of spatiotemporal parameters. Re-establishment of symmetry of CoM-CoP angle was reflected in re-established symmetry of spatiotemporal parameters in post-stroke and control participants. CONCLUSIONS: Post-stroke patients who re-establish symmetry of the COM-COP angle are able to adapt their walking for split-belt perturbation. This suggests that predictively symmetric foot placements on the fast and slow sides are necessary for adaptation in walking. Symmetrical foot placement is achieved by interlimb coordination and may contribute to dynamic stability.

Muscle synergies underlying sit-to-stand tasks in elderly people and their relationship with kinetic characteristics.

BACKGROUND: Physiological evidence suggests that the nervous system controls motion by using a low-dimensional synergy organization for muscle activation. Because the muscle activation produces joint torques, kinetic changes accompanying aging can be related to changes in muscle synergies. OBJECTIVES: We explored the effects of aging on muscle synergies underlying sit-to-stand tasks, and examined their relationships with kinetic characteristics. METHODS: Four younger and three older adults performed the sit-to-stand task at two speeds. Subsequently, we extracted the muscle synergies used to perform these tasks. Hierarchical cluster analysis was used to classify these synergies. We also calculated kinetic variables to compare the groups. RESULTS: Three independent muscle synergies generally appeared in each subject. The spatial structure of these synergies was similar across age groups. The change in motion speed affected only the temporal structure of these synergies. However, subject-specific muscle synergies and kinetic variables existed. CONCLUSIONS: Our results suggest common muscle synergies underlying the sit-to-stand task in both young and elderly adults. People may actively change only the temporal structure of each muscle synergy. The precise subject-specific structuring of each muscle synergy may incorporate knowledge of the musculoskeletal kinetics.