Tadanobu Suehiro

Individuals with chronic low back pain demonstrate delayed onset of the back muscle activity during prone hip extension

Prone hip extension (PHE) is commonly used in the evaluation of the stability of the lumbopelvic region. There is little evidence of difference in muscle activity onset timing between healthy individuals and individuals with chronic low back pain (CLBP) during PHE. The purpose of this study was to determine if individuals with and without CLBP differ in the onset time of the trunk and hip extensor muscles activity during PHE. The participants were 20 patients with CLBP and 20 healthy individuals. Electromyography data of the erector spinae, multifidus, gluteus maximus, and semitendinosus were collected during PHE using a surface electromyograph. Relative differences in the onset times between each muscle and the prime mover (i.e., the semitendinosus) were calculated. The onsets of the bilateral multifidus and contralateral erector spinae were significantly delayed in the CLBP group compared with the healthy group (p<0.001), despite the onset timings of leg movement not being significantly different between the groups. The onset times of the gluteus maximus and ipsilateral erector spinae showed no significant differences between the groups. These results suggest that individuals with CLBP use an altered, and possibly inadequate, trunk muscle recruitment pattern.

Comparison of spine motion and trunk muscle activity between abdominal hollowing and abdominal bracing maneuvers during prone hip extension.

The aim of this study was to examine the effects of lumbopelvic stabilization maneuvers on spine motion and trunk muscle activity during prone hip extension (PHE). In this study, 14 healthy male volunteers (mean age, 21.2 ± 2.6 years) were instructed to perform PHE without any maneuvers (control), with abdominal hollowing (AH), and with abdominal bracing (AB). Surface electromyography data were collected from the trunk muscles and the lumbopelvic motion was measured. Lumbar extension and anterior pelvic tilt degree were significantly lower in the AH and AB than in the control condition during PHE (p < 0.001). Lumbar extension and anterior pelvic tilt degree did not differ significantly between the AH and AB (p > 0.05). Global muscle group activity such as external obliques was lower in the AH than in the AB. These findings suggest that PHE with AH effectively minimizes unwanted lumbopelvic motion which does not result in global muscle activation.

Influence of Hip Joint Position on Muscle Activity during Prone Hip Extension with Knee Flexion

[Purpose] This study investigated the selective activation of the gluteus maximus during a prone hip extension with knee flexion exercise, with the hip joint in different positions. [Subjects] The subjects were 21 healthy, male volunteers. [Methods] Activities of the right gluteus maximus, right hamstrings, bilateral lumbar erector spinae, and bilateral lumbar multifidus were measured using surface electromyography during a prone hip extension with knee flexion exercise. Measurements were made with the hip joint in each of 3 positions: (1) a neutral hip joint position, (2) an abduction hip joint position, and (3) an abduction with external rotation hip joint position. [Results] Gluteus maximus activity was significantly higher when the hip was in the abduction with external rotation hip joint position than when it was in the neutral hip joint and abduction hip joint positions. Gluteus maximus activity was also significantly higher in the abduction hip joint position than in the neutral hip joint position. Hamstring activity was significantly lower when the hip was in the abduction with external rotation hip joint position than when it was in the neutral hip joint and abduction hip joint positions. [Conclusion] Abduction and external rotation of the hip during prone hip extension with knee flexion exercise selectively activates the gluteus maximus.

Association between trunk acceleration during walking and clinically assessed balance in patients with stroke

BACKGROUND Accelerometers provide information regarding balance and gait, but they are rarely used in clinical settings for stroke patients. Clinically, balance is assessed with simple tests, but their relationships with accelerometry results after stroke are unknown. OBJECTIVE We examined the relationship between accelerometry-assessed gait indices calculated from trunk acceleration and results of the Timed Up and Go (TUG) and Berg Balance Scale (BBS) tests in stroke patients. METHODS Twenty-nine stroke patients completed assessments with the TUG, BBS, and trunk acceleration during walking using a tri-axial accelerometer. The root mean square (RMS), stride regularity (SR), and step symmetry (SS), which indicate gait fluctuations, regularity, and symmetry, respectively, were calculated based on trunk acceleration. These were calculated in the vertical (VT), anteroposterior, and mediolateral directions. A multiple linear regression analysis was performed to determine whether these gait indices contributed independently to TUG and BBS results. RESULTS VT-RMS and VT-SS were significant determinants of TUG, and VT-SS, VT-RMS, and VT-SR were significant determinants of BBS. CONCLUSIONS This study suggested that the gait indices calculated from trunk acceleration that were relevant to balance were those in the VT direction. These may be useful for evaluating dynamic gait balance in patients with stroke.

Influence of Leg Support Elevation on Horizontal Force Acting on the Buttocksin a Reclining Wheelchair in Different Rotational Axis Positions of the BackSupport

Purpose: The purpose of this study was to investigate how the influences of leg support elevation on the horizontal force acting on the buttocks in a reclining wheelchair changes in various rotational axis positions of the back support. Materials and methods: The participants were 13 healthy men. The horizontal force was measured using a force plate on the experimental chair. Four experimental conditions were tested: the leg-down condition in the rearaxis and trochanter- axis positions of back support and the leg-up condition in the rear-axis and the trochanter- axis positions. The back support was reclined at increasing angles, beginning with the initial upright position (IUP) and proceeding to the fully reclined position (FRP). We calculated the variation rate of the forces acting on the buttocks between the FRP and the IUP (FRP/IUP*100: %). Results: In the trochanter-axis position, the variation rate of the leg-down and the leg-up conditions was 155.6 ± 29.1% and 119.3 ± 10.7%, respectively. In the rear-axis position, the variation rate of the leg-down and the leg-up condition were 100.7 ± 16.7% and 96.3 ± 10.2%, respectively. There were significant differences in the variation rate between the leg-down and leg-up conditions in the trochanter-axis position, but there were not significant differences in the rear-axis position. Conclusion: The extent of the influence of leg support elevation on the horizontal force acting on the buttocks in a reclining wheelchair decreases when the rotational axis of the back support is placed close to the trochanter.

Effect of abduction and external rotation of the hip joint on muscle onset time during prone hip extension with knee flexion.

[Purpose] This study investigated the effect of hip position on muscle onset time during prone hip extension with knee flexion. [Subjects] The study included 21 healthy male volunteers. [Methods] Muscle onset times of the right gluteus maximus, right hamstrings, bilateral lumbar erector spinae, and bilateral lumbar multifidus were measured using surface electromyography during right hip extension with knee flexion in the prone position. Measurements were made with the hip in 3 positions: (1) neutral, (2) abduction, and (3) abduction and external rotation. [Results] Gluteus maximus onset relative to the hamstrings was significantly earlier with hip abduction and with hip abduction and external rotation compared with that with the hip in the neutral position. Gluteus maximus onset relative to the hamstrings was significantly earlier with hip abduction and external rotation compared with that with hip abduction. The bilateral multifidus and left lumbar erector spinae onset times relative to the hamstrings were significantly earlier with hip abduction and external rotation compared with those with hip abduction and with the hip in the neutral position. [Conclusion] Abduction and external rotation of the hip during prone hip extension with knee flexion is effective for advancing the onset times of the gluteus maximus, bilateral multifidus, and contralateral lumbar erector spinae.