Immediate effects of stance and swing phase training on gait in patients with stroke.

To compare the effects of gait trainings targeting the stance (stance training) and the swing phases (swing training) among the subjects with stroke, and quantify the characteristics in the subjects who benefitted from either the stance training or the swing training. Sixteen subjects with stroke performed the stance training, which focused on the center of pressure to move from the heel to the forefoot, and the swing training, which focused on the improvement of hip flexion in the swing phase. To investigate the immediate effects of the stance training and the swing training, the instrumented gait analysis was performed before and after training. To quantify the characteristics, subjects were divided into two groups based on the gait speed change. These two groups were compared using clinical examinations. After the stance training, the center of pressure displacement of the paretic limb was increased compared with the swing training. Subjects who benefitted from the stance training had slower Timed Up and Go and weaker paretic hip muscle strength than those who benefitted from the swing training. Stance training may be more effective in subjects with slower Timed Up and Go outcomes and weaker hip muscles.

Gait kinematics and physical function that most affect intralimb coordination in patients with stroke.

BACKGROUND: Disturbed lower limb coordination is thought to limit gait ability in patients with stroke. However, the relationship of lower limb coordination with gait kinematics and physical function has not yet been clarified. OBJECTIVE: The purpose of the study was to clarify the gait kinematic and physical function variables that most affect intralimb coordination by using the continuous relative phase (CRP) between the thigh and shank. METHODS: Fifteen participants with stroke were enrolled in this study. Kinematic and kinetic measurements were recorded during gait at preferred speeds. CRP was defined as the difference between the thigh and shank phase angles. RESULTS: Stepwise analysis revealed that non-paretic CRP during the propulsive phase was a determinant of gait speed. The paretic knee extension and flexion angles were determinants of the CRP during the propulsive phase in the non-paretic limb. Stepwise analysis showed that the paretic knee extension angle was a determinant of the CRP during the propulsive phase in the paretic limb. Stepwise analysis revealed that the paretic knee extensor muscle strength was a determinant of the CRP during the propulsive phase in both limbs. CONCLUSIONS: Our study indicates that improvement in knee movement during the stance phase may improve coordination.

Back muscle activity and sagittal spinal alignment during quadruped upper and lower extremity lift in young men with low back pain history.

BACKGROUND: Quadruped upper and lower extremity lift (QULEL) is performed for selective training of the lumbar multifidus muscle in patients with low back pain (LBP) or individuals with LBP history (LBPH). However, the activities of the back muscles and sagittal spinal alignment during QULEL are not clarified in individuals with LBPH. RESEARCH QUESTION: This study aimed to analyze the activities of the back muscles and sagittal spinal alignment during QULEL in young male with LBPH. METHODS: The study comprised 9 asymptomatic young men and 8 young men with LBPH. The activities of the lumbar multifidus, latissimus dorsi and thoracic erector spinae, and lumbar erector spinae muscles were measured using surface electromyography. The flexion angles of the upper and lower thoracic spine, and extension angle of the lumbar spine were measured using a 6-DF electromagnetic motion tracking system. The association with LBPH was investigated using multiple logistic regression analysis with a forward selection method, with the activities of the back muscles, sagittal spinal alignment, age, body height, and body weight as independent variables. RESULTS: Multiple logistic regression analysis (p = 0.0002) showed that the activity of the latissimus dorsi and thoracic erector spinae muscles in the side on which the lower extremity was lifted and body height were significant and independent determinants of LBPH, but other factors were not. SIGNIFICANCE: The results of this study suggest that the activity of the latissimus dorsi and thoracic erector spinae muscles increases while there are no decrease in activity of the lumbar multifidus muscle and excessive extension of the lumbar spine during QULEL in young men with LBPH.

Ankle muscle coactivation and its relationship with ankle joint kinematics and kinetics during gait in hemiplegic patients after stroke.

INTRODUCTION: Increased ankle muscle coactivation during gait is a compensation strategy for enhancing postural stability in patients after stroke. However, no previous studies have demonstrated that increased ankle muscle coactivation influenced ankle joint movements during gait in patients after stroke. PURPOSE: To investigate the relationship between ankle muscle coactivation and ankle joint movements in hemiplegic patients after stroke. METHODS: Seventeen patients after stroke participated. The coactivation index (CoI) at the ankle joint was calculated separately for the first and second double support (DS1 and DS2, respectively) and single support (SS) phases on the paretic and non-paretic sides during gait using surface electromyography. Simultaneously, three-dimensional motion analysis was performed to measure the peak values of the ankle joint angle, moment, and power in the sagittal plane. Ground reaction forces (GRFs) of the anterior and posterior components and centers of pressure (COPs) trajectory ranges and velocities were also measured. RESULTS: The CoI during the SS phase on the paretic side was negatively related to ankle dorsiflexion angle, ankle plantarflexion moment, ankle joint power generation, and COP velocity on the paretic side. Furthermore, the CoI during the DS2 phase on both sides was negatively related to anterior GRF amplitude on each side. CONCLUSION: Increased ankle muscle coactivation is related to decreased ankle joint movement during the SS phase on the paretic side to enhance joint stiffness and compensate for stance limb instability, which may be useful for patients who have paretic instability during the stance phase after stroke.

Clinical factors associated with ankle muscle coactivation during gait in adults after stroke.

BACKGROUND: Increased ankle muscle coactivation during gait represents an adaptation strategy to compensate for postural instability in adults after stroke. Although increased ankle muscle coactivation is correlated with gait disorders in adults after stroke, it remains unclear which physical impairments are the most predictive clinical factors explaining ankle muscle coactivation during gait. OBJECTIVE: To investigate these physical impairments in adults after stroke using stepwise multiple regression analyses. METHODS: The magnitude of ankle muscle coactivation during gait was quantified with a coactivation index (CoI) for the first and second double support (DS2), and single support (SS) phases in 44 community-dwelling adults after stroke. Paretic motor function, sensory function, spasticity, ankle muscle strength, and balance ability were evaluated. RESULTS: The regression analysis revealed that the balance ability and paretic ankle plantarflexor muscle strength were significant factors determining the CoI during the SS phase on the paretic side. For the CoI during the DS2 phase on the paretic side, only the balance ability was selected as a significant factor. CONCLUSION: Adults with impaired balance ability and paretic ankle muscle weakness after stroke used a compensation strategy of increased ankle muscle coactivation on the paretic side to enhance postural stability during gait.

Ankle muscle coactivation during gait is decreased immediately after anterior weight shift practice in adults after stroke.

Increased ankle muscle coactivation during gait has frequently been observed as an adaptation strategy to compensate for postural instability in adults after stroke. However, it remains unclear whether the muscle coactivation pattern increases or decreases after balance training. The aim of this study was to investigate the immediate effects of balance practice on ankle muscle coactivation during gait in adults after stroke. Standing balance practice performed to shift as much weight anteriorly as possible in 24 participants after stroke. The forward movement distance of the center of pressure (COP) during anterior weight shifting, gait speed, and ankle muscle activities during 10-m walking tests were measured immediately before and after balance practice. Forward movement of the COP during anterior weight shifting and gait speed significantly increased after balance practice. On the paretic side, tibialis anterior muscle activity significantly decreased during the single support and second double support phases, and the coactivation index at the ankle joint during the first double support and single support phases significantly decreased after balance practice. However, there were no significant relationships between the changes in gait speed, forward movement of the COP during anterior weight shifting, and ankle muscle coactivation during the stance phase. These results suggested that ankle muscle coactivation on the paretic side during the stance phase was decreased immediately after short-term anterior weight shift practice, which was not associated with improved gait speed or forward movement of the COP during anterior weight shifting in adults after stroke.

Merging and Fractionation of Muscle Synergy Indicate the Recovery Process in Patients with Hemiplegia: The First Study of Patients after Subacute Stroke.

Loss of motor coordination is one of the main problems for patients after stroke. Muscle synergy is widely accepted as an indicator of motor coordination. Recently, the characteristics of muscle synergy were quantitatively evaluated using nonnegative matrix factorization (NNMF) with surface electromyography. Previous studies have identified that the number and structure of synergies were associated with motor function in patients after stroke. However, most of these studies had a cross-sectional design, and the changes in muscle synergy during recovery process are not clear. In present study, two consecutive measurements were conducted for subacute patients after stroke and the change of number and structure of muscle synergies during gait were determined using NNMF. Results showed that functional change did not rely on number of synergies in patients after subacute stroke. However, the extent of merging of the synergies was negatively associated with an increase in muscle strength and the range of angle at ankle joint. Our results suggest that the neural changes represented by NNMF were related to the longitudinal change of function and gait pattern and that the merging of synergy is an important marker in patients after subacute stroke.

Association of sagittal spinal alignment with thickness and echo intensity of lumbar back muscles in middle-aged and elderly women.

OBJECTIVE: Quantitative changes, such as a decrease in muscle mass, and qualitative changes, such as an increase in the amount of intramuscular non-contractile tissue, occur with aging. However, it is unclear whether quantitative or qualitative changes in back muscles are associated with spinal alignment in the standing position. We investigated the association of sagittal spinal alignment with muscle thickness as an index of the mass of lumbar back muscles and muscle echo intensity as an index of the amount of non-contractile tissue within these muscles. METHODS: Study participants comprised 36 middle-aged and elderly women. Thickness and echo intensity of erector spinae, psoas major, and lumbar multifidus muscles were measured using an ultrasound imaging device. Standing sagittal spinal alignment, determined from thoracic kyphosis and lumbar lordosis angles, and the sacral anterior inclination angle was measured using the Spinal Mouse. RESULTS: Stepwise regression analysis performed using muscle thickness, echo intensity, and age as independent variables showed that erector spinae muscle thickness was a significant determinant of the thoracic kyphosis angle. Psoas major muscle thickness and echo intensity of the lumbar multifidus muscle were significant determinants of the sacral anterior inclination angle. CONCLUSION: Our results suggest that an increase in thoracic kyphosis is associated with a decrease in the mass of the erector spinae muscle, and that a decrease in pelvic anterior inclination is associated with a decrease in the mass of the psoas major muscle and an increase in the amount of non-contractile tissue within the lumbar multifidus muscle.

Relation between abnormal synergy and gait in patients after stroke.

BACKGROUND: The abnormal synergy seen in patients after stroke is considered to limit the ability of these patients. However, in the lower extremity, antigravity torque generation rather than precise movement is needed for functions such as sit-to-stand movement and gait. Therefore, the ability to generate torque may be important either as a primary movement or as an abnormal synergy. We attempted to quantify the torque generation in the lower limb, selectively and as an abnormal synergy, and its relation with gait. METHODS: Selectively generated plantar flexion torque in the ankle and plantar flexion torque secondarily generated accompanying maximal hip extension (i.e., torque generated with abnormal synergy) were measured in subjects after stroke and control subjects. In subjects after stroke, secondary torque generation while controlling hip extension torque as 25%, 50%, and 75% of the maximal hip extension was also measured. The relation of torque generation with the gait speed and timed-up-and go test (TUG) was also analyzed. RESULTS: In subjects after stroke, there was no difference between the amount of plantar flexion torque generated secondarily and the selectively generated torque, whereas the selective torque was significantly greater in control subjects. Pearson product-moment correlation coefficient analysis revealed that TUG speed is related to secondarily generated torque accompanying maximal hip extension but not with selectively generated torque. CONCLUSION: Secondarily generated torque was found to be a factor that affects TUG speed, and the ability to generate torque even through abnormal synergy may help for gait ability in subjects after stroke.