Effectiveness of knee pad as an additional device for wheelchairs in improving upper-limb dexterity during seated tasks: a pilot study

[Purpose] This study aimed to examine how supporting the knee from the front with a knee pad affected upper-limb dexterity while sitting. [Participants and Methods] A total of 14 healthy adult males were included in the study. As a measure of upper-limb dexterity, the number of pins was counted when the Purdue pegboard test was performed for 60 seconds. In addition, the ease of task performance was assessed using the visual analogue scale. There were two experimental conditions, with and without knee pad. The paired t-test was used to detect differences between the two conditions. A p-value of 0.05 was considered statistically significant. [Results] The Purdue pegboard test was 29.4 ± 2.5 and 27.9 ± 3.6 pins with and without knee pad, respectively. The VAS was 76.1 ± 10.3 and 62.9 ± 14.1 with and without knee pad, respectively. Both measured values were significantly higher with knee pad than without. [Conclusion] Supporting the knees from the front with knee pad improves upper-limb functionality while sitting, making it easier to perform seated tasks.

Effect of shape of back support adjustment on shear force applied to buttocks when tilt-in-space and reclining functions are combined in wheelchairs

PURPOSE

This study aimed to investigate the effect of the shape of the back support adjustment on the shear force applied to the buttocks when tilt-in-space and reclining functions are combined in wheelchairs.

MATERIALS AND METHODS

Fourteen healthy adult men were included in the study. The force plate was used to measure the parallel force as shear force. The measurement posture, leaning against the back support of an experimental chair, was a comfortable sitting posture. The tilt-in-space angle was set to 15°. The back support was inclined at increasing angles, starting from the upright position (IUP), proceeding to a fully reclined position (FRP), and returning to the upright position (RUP). The experimental conditions were as follows: adjusting the back-support shape (aBS) and non-adjusting the back support shape (non-aBS).

RESULTS

Positive values indicate a parallel force applied to the buttocks posteriorly. The average values in the aBS condition were 3.4 ± 2.3, 13.6 ± 2.2, and -7.1 ± 2.4% body weight in the IUP, FRP, and RUP, respectively. The average values in the non-aBS condition were 3.8 ± 2.5, 11.4 ± 2.1, and -6.2 ± 3.1% body weight in the IUP, FRP, and RUP, respectively. There were significant differences between the two conditions in FRP (p < 0.01).

CONCLUSION

These findings suggest that the shape of the back support adjustment function increased the shear force applied to the buttocks posteriorly when the back support was inclined backwards using both the tilt-in-space and reclining functions.IMPLICATIONS FOR REHABILITATIONWhen utilizing both the tilt-in-space and reclining functions to incline the back support, the shear force applied to the buttocks is greatly affected by the shape of the back support.The shape of back support adjustment is a function that can stabilize elderly persons' sitting posture, but it may increase the external force applied to the buttocks and back.

Investigation of the effect of a 15-degree tilt-in-space on the fluctuation of shear forces exerted on the buttocks when the back support is reclined

[Purpose] This study aimed to investigate the effect of the combination of 15° tilt-in-space and recline angles on the fluctuation of shear forces exerted on the buttocks. [Participants and Methods] The participants were 11 healthy adult males. The parameters of the shear forces were the parallel and perpendicular forces exerted on the buttocks as measured by a force plate. The two conditions tested were T0R100-130 and T15R100-130. The tilt-in-space angles were set to 0° and 15° in the T0R100-130 and T15R100-130 conditions, respectively. The reclining angles were determined to be 100° to 130° in both conditions. [Results] Upon comparing the two conditions, the parallel and the perpendicular forces exerted on the buttocks in the T15R100-130 condition were significantly lower than those in the T0R100-130 condition in all positions of back support. Upon comparing the fluctuation values of the parallel and perpendicular forces, those applied in the T15R100-130 condition were significantly higher than those in the T0R100-130 condition. [Conclusion] These results suggest that the fluctuation of shear forces exerted on the buttocks could be decreased by using a combination of 15° tilt-in-space and reclining functions.

Trunk muscle activation patterns during active hip abduction test during remission from recurrent low back pain: an observational study

Background

The active hip abduction test (AHAbd) is widely used to evaluate lumbopelvic stability, but the onset of trunk muscle activation during the test in individuals with recurrent low back pain (rLBP) has not been investigated so far. It is important to investigate the pattern of trunk muscle activation during the AHAbd test to provide insight into the interpretation of observation-based assessment results; this may help to create exercise therapy interventions, from a movement control perspective, for people seeking treatment for rLBP. The purpose of this study was to compare the timing of trunk muscle activation between individuals with and without rLBP and to assess potential differences.

Methods

Seventeen subjects in remission from rLBP and 17 subjects without rLBP were recruited. We performed surface electromyography of the transversus abdominis/internal abdominal oblique, external oblique, erector spinae, and gluteus medius muscles during the AHAbd test on both sides. The onset of trunk muscle activation was calculated relative to the prime mover gluteus medius. The independent-samples t- and Mann-Whitney U tests were used to compare the onset of trunk muscle activation between the two groups.

Results

The onset of transversus abdominis/internal abdominal oblique activation on the ipsilateral (right AHAbd: −3.0 ± 16.2 vs. 36.3 ± 20.0 msec, left AHAbd: −7.2 ± 18.6 vs. 29.6 ± 44.3 ms) and contralateral sides (right AHAbd: −11.5 ± 13.9 vs. 24.4 ± 32.3 ms, left AHAbd: −10.1 ± 12.5 vs. 23.3 ± 17.2 ms) and erector spinae on the contralateral side (right AHAbd: 76.1 ± 84.9 vs. 183.9 ± 114.6 ms, left AHAbd: 60.7 ± 70.5 vs. 133.9 ± 98.6 ms) occurred significantly later in individuals with rLBP than in individuals without rLBP (p < 0.01). During the left AHAbd test, the ipsilateral erector spinae was also activated significantly later in individuals with rLBP than in individuals without rLBP (71.1 ± 80.1 vs. 163.8 ± 120.1 ms, p < 0.05). No significant difference was observed in the onset of the external oblique activation on the right and left AHAbd tests (p > 0.05).

Conclusions

Our results suggest that individuals with rLBP possess a trunk muscle activation pattern that is different from that of individuals without rLBP. These findings provide an insight into the underlying muscle activation patterns during the AHAbd test for people with rLBP and may support aggressive early intervention for neuromuscular control.

Immediate Effect of Restricted Knee Extension on Ground Reaction Force and Trunk Acceleration during Walking

Gait parameters calculated from trunk acceleration reflect the features of gait; however, they cannot evaluate the gait pattern corresponding to the gait cycle. This study is aimed at investigating the differences in gait parameters calculated from trunk acceleration during gait corresponding to the gait cycle in healthy subjects with restricted knee extension. Participants included eight healthy volunteers who walked normally (NW) and with knee orthosis that restricted knee extension (ER). The ground reaction force (GRF), joint angles, and trunk acceleration during walking were measured using four force plates, a three-dimensional motion analysis system, and an inertial measurement unit. The peak GRF of the vertical components, joint ranges of motion, and moments of force were analyzed. The root mean square (RMS) and amplitude peak ratio (AR) of autocorrelation function were calculated from the trunk acceleration waveform. The first peak GRF and peak ankle dorsiflexion angles significantly increased during ER. The peak hip extension, knee flexion, knee extension angles, and the peak moment of knee extension significantly decreased during ER compared to that during NW. The acceleration AR significantly decreased during ER compared to that during NW. There was no significant difference in the RMS between the two conditions. The acceleration AR may show the temporal postural structure with restricted knee extension from the terminal stance phase for the ipsilateral limb to the initial stance phase for the contralateral limb. These results suggest that novel metrics for accelerometry gait analysis can reveal gait abnormalities, with restricted knee extension corresponding to the gait cycle.

Immediate changes in trunk muscle activation patterns during a lifting task following an abdominal drawing-in exercise in subjects with recurrent low back pain

BACKGROUND

The abdominal drawing-in exercise could help improve delayed transversus abdominis (TrA) activation during limb movement in subjects with recurrent low back pain (rLBP). However, little is known about whether the same effect is observed during lifting tasks in subjects with rLBP.

OBJECTIVE

This study aimed to clarify whether a single session of abdominal drawing-in exercise could correct the altered trunk muscle activation patterns during a lifting task in subjects with rLBP.

METHODS

Fifteen subjects with rLBP performed lifting tasks before and immediately after three sets of 10 repetitions of isolated TrA voluntary contractions. The time of onset and activation amplitude during the lifting tasks were measured by surface electromyography (EMG) and compared between the trials before and immediately after exercise.

RESULTS

During lifting, the onset of internal abdominal oblique/TrA (IO/TrA) and multifidus activation occurred earlier, the EMG amplitude of IO/TrA increased, and the EMG amplitude of erector spinae and multifidus decreased, compared with the pre-exercise data.

CONCLUSIONS

These results suggest a possibility that the abdominal drawing-in exercise might be effective in improving the muscle recruitment pattern in people with rLBP.

Effect of asymmetrical buttock pressure on forces exerted in buttock movement when using a reclining chair

[Purpose] To clarify the effect of asymmetrical buttock pressure on the shear forces exerted on a buttock. [Participants and Methods] Sixteen healthy adult males participated in this study. A cushion 0 or 2 cm high was placed on the left side of the seat for all participants. The 0- and 2-cm height conditions were called “without difference condition” and “difference condition”, respectively. The back support was inclined at increasing angles, starting at the upright position, to a fully reclined position, and back to the upright position. [Results] With the “difference condition”, the force on the left buttock was 147.4% body weight and that on the right buttock was 105.6% body weight. In contrast, with the “without difference condition”, there was no significant difference in the force on the left buttock and right buttock in terms of percent body weight. [Conclusion] Our results suggest that asymmetrical buttock pressure while in the sitting position causes a difference in shear force exerted on the left and right buttocks when using a reclining chair.

An investigation into the effectiveness of a novel wheelchair seat-cover assembly for the reduction of forces exerted onto the buttocks

Purpose: This purpose was to investigate developed seat-cover assemblies' effect on decreasing the fluctuation of the shear force exerted onto the buttocks as the factors causing decubitus ulcers when the back-support was inclined.Materials and Methods: The participants were 10 wheelchair users. The force plate was used to measure the horizontal force as the shear force. The back-support was inclined at increasing angles, starting from the upright position (IUP), then proceeding to a fully reclined position (FRP), and returning to the upright position (RUP). The experimental conditions were two conditions; the seat-cover assembly conditions and without the seat-cover assembly as the control conditions.Results: The average values in the seat-cover assembly condition were 14.4 ± 3.3, 13.9 ± 2.3, and 17.3 ± 3.3% body weight in the IUP, FRP, and RUP, respectively. The average values in the control condition were 14.8 ± 2.6, 11.4 ± 1.7, and 24.0 ± 6.7% body weight in the IUP, FRP, and RUP, respectively. In the FUP and the RUP, there were significant differences between two conditions (p < .01).Conclusion: These results suggested that the shear force exerted onto the buttocks may to be decreased by using novel seat-cover assembly.Implications for rehabilitationIt is possible to decrease the fluctuations in the shear force by moving the body up and down according the novel seat-cover assembly attached the back-support incline.Disabled, older individuals can be provided with a comfortable life on a reclining wheelchair while preventing decubitus ulcers.

01 Prediction of Falls in Community-Dwelling Older People using an Accelerometer: The Results of a 1-Year Prospective Study

Background

Fall preventive exercise for community-dwelling older people in Japan has a certain effect. The purpose of this study was to examine the predictors of fall risk in older people engaging in preventive exercise.

Methods

In this prospective study, we recruited 162 community-dwelling older people. We had them complete a self-report questionnaire containing items on weekly exercise frequency, exercise duration, exercise efficacy, amount of pain, number of diagnosis chronic diseases, health anxiety level, vision impairment, difficulty using the stairs, insomnia, fear of falling, history of falls, and forgetfulness, as well as the Falls Efficacy Scale. Walking speed and trunk acceleration during walking were also measured in all participants. From trunk acceleration, we calculated five gait parameters: fluctuation, weight shift, lateral balance, anteroposterior balance, and rhythm. Participants were classified as fallers or non-fallers according to the incidence of falls over a 1-year period from baseline assessment.

Results

Of all participants, 19 (11.7%) were classified as fallers and 143 (88.3%) as non-fallers. In comparing the fallers and non-fallers, we found significant differences in their exercise duration, exercise efficacy, amount of pain, history of falls, walking speed, and the gait parameters of weight shift and anteroposterior balance. A logistic regression analysis revealed that walking speed (odds ratio: 0.049, 95% confidence interval [CI]: 0.005-0.265, p=0.008) and weight shift (odds ratio: 0.021, 95%CI: 0.000-0.877, p=0.043) were predictors of falls.

Conclusion

The gait parameter of weight shift is the amplitude ratio of the auto-correlation function from vertical acceleration. This gait parameter is an original metrics and might show the temporal structure around the terminal stance. Measurement of gait parameters, in addition to physical performance, using an accelerometer seems beneficial for fall risk identification among community-dwelling older people engaged in fall preventive exercise.

Muscle activity during backward perturbation response in patients with clinical vertebral compression fractures

The present study examined muscle activity in response to backward perturbation in patients with clinical vertebral compression fracture (CVCF). The subjects were 32 patients aged 65 years and above consisting of 16 each with (CVCF group) and without (control group) CVCF. The time to peak activity, and time of onset of muscle activity of the anterior tibial, vastus medialis, and rectus abdominis muscles when unexpected backward perturbation was applied were evaluated by surface electromyography. The strength of perturbation was 4% or 6% of the subject's body weight. In addition, the presence of the stepping reaction to perturbation, severity of low back pain, and vertebral alignment were evaluated. Each item was compared between the two groups. In the CVCF group, kyphosis and severity of low back pain were significantly more severe, the time to peak activity of the anterior tibial muscle after the application of perturbation at 6% of the body weight was significantly shorter, and the time of onset of activity of the rectus abdominis muscle was significantly delayed. This suggests that the time to peak activity of the anterior tibial muscle is shortened and the time of onset of activity of the rectus abdominis muscle is delayed in unexpected backward perturbation in patients with CVCF.

Tape measure-based real-time feedback during the abdominal draw-in maneuver facilitates isolated transverse abdominal contraction

[Purpose] Although the abdominal draw-in maneuver improves delayed onset of transverse abdomen in patients with low back pain, it is difficult to perform. We investigated whether the maneuver with tape measure-based feedback was more effective in facilitating isolated transverse abdominal muscle contractions than that without feedback in healthy participants. [Participants and Methods] Twenty healthy males performed the maneuver without feedback (control condition) and then with feedback using a tape measure (tape measure condition) in the crook lying, sitting, and standing positions. A B-mode ultrasonography imaging system was used to determine lateral abdominal muscle thicknesses, the percent changes from before the maneuver were calculated for each condition, and the main effects and interactions for each tested muscle were determined. [Results] The percent change in the thickness of the transverse abdominal muscle was significantly greater under the tape measure condition than under the control condition. The percent change in internal oblique thickness during the maneuver was significantly greater in the standing position than in the crook lying or sitting positions. Significant condition-by-position interactions were not observed for any of the examined muscles. [Conclusion] The abdominal draw-in maneuver with tape measure-based feedback may be more effective at facilitating isolated transverse abdominal contractions in all the positions than that without feedback.

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.

Clinical experience with a single-nucleotide polymorphism-based non-invasive prenatal test for five clinically significant microdeletions

Single-nucleotide polymorphism (SNP)-based non-invasive prenatal testing (NIPT) can currently predict a subset of submicroscopic abnormalities associated with severe clinical manifestations. We retrospectively analyzed the performance of SNP-based NIPT in 80 449 referrals for 22q11.2 deletion syndrome and 42 326 referrals for 1p36, cri-du-chat, Prader-Willi, and Angelman microdeletion syndromes over a 1-year period, and compared the original screening protocol with a revision that reflexively sequenced high-risk calls at a higher depth of read. The prevalence of these microdeletion syndromes was also estimated in the referral population. The positive predictive value of the original test was 15.7% for 22q11.2 deletion syndrome, and 5.2% for the other 4 disorders combined. With the revised protocol, these values increased to 44.2% for 22q11.2 and 31.7% for the others. The 0.33% false-positive rate (FPR) for 22q11.2 deletion syndrome decreased to 0.07% with the revised protocol. Similarly, the FPR for the other 4 disorders combined decreased from 0.56% to 0.07%. Minimal prevalences were estimated to be 1 in 1255 for 22q11.2 deletion syndrome and 1 in 1464 for 1p36, cri-du-chat, and Angelman syndromes combined. Our results show that these microdeletions are relatively common in the referral population, and that the performance of SNP-based NIPT is improved with high-depth resequencing.

Clinical experience with single-nucleotide polymorphism-based non-invasive prenatal screening for 22q11.2 deletion syndrome

OBJECTIVES

To evaluate the performance of a single-nucleotide polymorphism (SNP)-based non-invasive prenatal test (NIPT) for the detection of fetal 22q11.2 deletion syndrome in clinical practice, assess clinical follow-up and review patient choices for women with high-risk results.

METHODS

In this study, 21 948 samples were submitted for screening for 22q11.2 deletion syndrome using a SNP-based NIPT and subsequently evaluated. Follow-up was conducted for all cases with a high-risk result.

RESULTS

Ninety-five cases were reported as high risk for fetal 22q11.2 deletion. Diagnostic testing results were available for 61 (64.2%) cases, which confirmed 11 (18.0%) true positives and identified 50 (82.0%) false positives, resulting in a positive predictive value (PPV) of 18.0%. Information regarding invasive testing was available for 84 (88.4%) high-risk cases: 57.1% (48/84) had invasive testing and 42.9% (36/84) did not. Ultrasound anomalies were present in 81.8% of true-positive and 18.0% of false-positive cases. Two additional cases were high risk for a maternal 22q11.2 deletion; one was confirmed by diagnostic testing and one had a positive family history. There were three pregnancy terminations related to screening results of 22q11.2 deletion, two of which were confirmed as true positive by invasive testing.

CONCLUSIONS

Clinical experience with this SNP-based non-invasive screening test for 22q11.2 deletion syndrome indicates that these deletions have a frequency of approximately 1 in 1000 in the referral population with most identifiable through this test. Use of this screening method requires the availability of counseling and other management resources for high-risk pregnancies.

Influence of rotational axis height of back support on horizontal force applied to buttocks in a reclining wheelchair

BACKGROUND

Studies have not been conducted to investigate the influence of the height of the rotational axis of a wheelchair's back support on the shear force applied to the buttocks during the reclining motion.

OBJECTIVES

The purpose of this study was to investigate the influence of the difference in the rotational axis position of back support in the vertical direction on the horizontal force applied to buttocks for preventing decubitus ulcers.

STUDY DESIGN

Repeated measures design.

METHODS

The subjects were 13 healthy adult men without leg and/or trunk diseases. The shear force was measured using a force plate. A comfortable sitting posture in the experimental chair was selected for measurement. The rotational axis was positioned 13 cm forward on the horizontal plane from the intersection between the seat and the back support. The axis positions on the vertical plane as two experimental conditions were the seat height and the 7.5-cm upward from the seat height which was nearer to the hip joint.

RESULTS

In returning the back support to an upright position, the horizontal force was 12.4 ± 1.6 (percent body weight) under the seat height-axis condition and 10.1 ± 1.8 (percent body weight) under the upward-axis condition (p < 0.01).

CONCLUSION

This result suggested that the wheelchair might have to be capable of adjusting the height of the rotational axis of the back support to reduce the horizontal force applied to buttocks.

CLINICAL RELEVANCE

This study shows one of the suggestions regarding seating approach for the prevention of decubitus ulcers. There is a possibility of reducing horizontal force applied to buttocks after reclined back support, by adjusting the height of the rotational axis position of wheelchair back support.

Investigation of effect of leg support elevation timing on the horizontal force acting on the buttocks in a reclining wheelchair

[Purpose] The purpose of this study was to investigate the effect of the timing of leg support elevation on the horizontal force acting on the buttocks in a reclining wheelchair. [Subjects and Methods] The participants were 17 healthy men. Two experimental conditions were tested: the leg-down and leg-up conditions. The back support was reclined at increasing angles, from the initial upright position (IUP), proceeding to the fully reclined position (FRP), and returned to the upright position (RUP). The posterior inclination phase was from IUP to FRP, and the returning inclination phase was from FRP to RUP. [Results] The horizontal force under the leg-up condition was significantly higher than that under the leg-down condition in all positions of back support. [Conclusion] The leg supports should be positioned downward before reclining the back support of a wheelchair.

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.

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.

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.

Correlation between Peak Expiratory Flow and Abdominal Muscle Thickness

[Purpose] The purpose of this study was to determine whether forced expiration is correlated with abdominal muscle thickness. [Subjects] Twenty-three healthy male volunteers participated in this study. [Methods] The peak expiratory flow (PEF) was obtained using a peak flow meter with subjects in the sitting position. The thicknesses of the right rectus abdominis, external oblique, internal oblique, and transverse abdominis muscles were measured using B-mode ultrasonography at the end of a relaxed expiration in the supine position. [Results] Among the abdominal muscles, only the thickness of the external oblique muscle displayed a significant correlation with PEF. [Conclusion] It appears that the thickness of the external oblique muscle might be associated with PEF during forced expiration.

Influence of trunk muscle co-contraction on spinal curvature during sitting

BACKGROUND AND PURPOSE

Slumped sitting is known to increase disc pressure and aggravate chronic low back pain. In addition, it has been recognized that co-contraction of the deep spine-stabilizing muscles enhances lumbar segmental stability and the sacro-iliac joint. The purpose of this study was to compare the electromyographic (EMG) activity of the trunk muscles and the muscle thickness of the transverse abdominis (TrA) during slumped sitting with the same parameters during co-contraction and investigate how co-contraction influences spinal curvature.

SUBJECTS AND METHODS

Nine healthy male volunteers participated in the study. EMG signals were recorded during both sitting postures. In order to measure the muscle thickness of the TrA, ultrasound images were captured. While the subjects performed both sitting postures, spinal curvature was measured using a hand-held device.

RESULTS

Significantly more activity of the trunk muscles, with the exception of the rectus abdominis muscle, and significantly greater muscle thickness of the TrA were observed during co-contraction of the trunk muscles than during slumped sitting. Co-contraction also resulted in significantly increased lumbar lordosis and a greater sacral angle when compared to slumped sitting.

CONCLUSION

In this study, it was demonstrated that the instructions given to the subjects on co-contraction of the trunk muscles during sitting increased muscle activity with the exception of the rectus abdominis muscle, muscle thickness of the TrA, and lumbar lordosis.

Intra-rater and inter-rater reliabilities of real-time acceleration gait analysis system

PURPOSE

The purposes of this study were to construct a real-time acceleration gait analysis system equipped with software to analyse real-time trunk acceleration during walking and to examine the intra-rater and inter-rater reliabilities of the this system.

METHODS

This system has been comprised of an accelerometer, an acceleration amplifier, a transmitter, two foot switches, a receiver and a personal computer installed with the real-time acceleration analysis software. The acceleration signals received were analysed using the real-time acceleration analysis software, and gait parameters were calculated. The subjects were 20 healthy individuals and two raters. The intra-rater and inter-rater reliabilities of the measurement results obtained from this system were examined by performing intraclass correlation coefficients (ICC) and Bland-Altman analysis.

RESULTS

The intra-rater and inter-rater ICCs ranged from 0.61 to 0.92 in any gait parameters. In the Bland-Altman analysis, neither fixed nor proportional bias was found in any of the gait parameters.

CONCLUSIONS

From the ICC and Bland-Altman analysis results, the gait measurement using this system clearly demonstrates that the intra-rater and inter-rater measurements had good reproducibility. Owing to this system, we can improve the clinical efficiency of gait analysis and gait training for physiotherapy. Implication for Rehabilitation This study focused on the advantage of a gait analysis method using an accelerometer and constructed a gait analysis system that calculates real-time gait parameters from trunk acceleration measurements during walking. The gait analysis using this system has good intra-rater and inter-rater reliabilities, and using this system can improve the clinical efficiency of gait analysis and gait training.

Effect of rotational axis position of wheelchair back support on shear force when reclining

[Purpose] The purpose of this study was to investigate the influence of the rotational axis position of a reclining wheelchair's back support on fluctuations in the shear force applied to the buttocks while the back support is reclined. [Subjects] The subjects were 12 healthy adult men. [Methods] The shear force applied to the buttocks was measured using a force plate. This study used two different experimental conditions. The rotational axis of the back support was positioned at the joint between the seat and the back support for the rear-axis condition, and was moved 13 cm forward for the front-axis condition. [Results] With the back support fully reclined, the shear forces were 11.2 ± 0.8%BW and 14.1 ± 2.5%BW under the rear-axis and front-axis conditions, respectively. When returned to an upright position, the shear forces were 17.1 ± 3.1%BW and 13.8 ± 1.7%BW under the rear-axis and front-axis conditions, respectively. Significant differences appeared between the two experimental conditions (p < 0.01). [Conclusion] These results suggest that the shear force value could be changed by altering the position of the back support's rotational axis during reclining.

Influence of distance between the rotation axis of back support and the hip joint on shear force applied to buttocks in a reclining wheelchair's back support

PURPOSE

The purpose of this study was to investigate the influence of the distance between the position of the rotation axis of the back support and hip joint on the changes in the shear force applied to the buttocks.

STUDY DESIGN

Repeated-measures design.

METHODS

The subjects were 11 healthy adult men without leg and/or trunk diseases. The shear force applied to the buttocks was measured using a force plate. This study had three experimental conditions: the position of hip joint was taken as the 3 cm, 6 cm, and 9 cm forward from the standard sitting position.

RESULTS

In returning to an upright position of back support, the shear force was 15.0 ± 2.9 %BW in the 3 cm forward condition, 16.7 ± 3.6 %BW in the 6 cm forward condition, and 19.5 ± 5.3 %BW in the 9 cm forward condition. Significant differences appeared between the 9 cm and the other conditions (p < 0.05).

CONCLUSIONS

The results of this study suggested that the shear force applied to the buttocks changed in reclining back support and an increase in the distance between the axis of rotation of the back support and hip joint led to an increase in the remaining shear force after reclining the back support.

Mechanism of fluctuation in shear force applied to buttocks during reclining of back support on wheelchair

PURPOSE

The purpose of this study was to investigate the mechanism of the fluctuation in the shear force applied to the buttocks.

METHOD

The subjects were 11 healthy adult men without leg or trunk diseases. The amount of force applied to the buttocks was measured by using a force plate, and a pressure and shear force sensor was used to measure the timing of the force applied to the back support.

RESULTS

The average value of the shear force applied to the buttocks was 9.4 ± 2.4 (%BW) in the initial upright position (IUP), 9.3 ± 1.2 (%BW) in the fully reclined position (FRP), and 15.0 ± 2.9 (%BW) in the returning to an upright position (RUP). Significant differences appeared between the RUP and the other positions.

CONCLUSIONS

The results of this study suggested that the adjustment of the axes of rotation of the back support and trunk-pelvis and the release of the remaining shear force after the back support is reclined are important for the prevention of decubitus ulcers.

Influence of fingertip contact with a wall on postural sway and electromyographyic activity of the soleus muscle

Standing and walking balance decreases in many kinds of neuromuscular, musculoskeletal and sensory disorders, and in elderly people because of age-related physiologic diminution. Recent studies have shown that contact cues from a cane or a fingertip provide information that leads to reduced postural sway in subjects. The first purpose of this study was to investigate the influence of light and forceful fingertip contacts with a wall on the postural sway while standing upright. The second purpose was to investigate the influence of fingertip contact on the EMG activity of the soleus muscle. Twelve healthy male volunteers (20.8 +/- 0.7 years old) participated in this study. Standing balance or postural sway was measured by sway of the center of pressure (COP) under three conditions: (1) standing without touching a wall, (2) standing with the right index fingertip lightly touching (< 1N) to a wall (3), and standing with the right index fingertip forcefully touching (5 approximately 10N) to a wall. Bipolar surface electrodes were placed over the right soleus muscle to measure EMG activity associated with anterior-posterior sway. More significant length, and rectangular and environmental areas of the COP were observed while standing without touching a wall than while standing while lightly or forcefully touching a wall, but there was no significant difference between the two touching conditions. No significant difference in the EMG activity of the soleus muscle was observed among the three conditions. The results of this study suggested that the fingertip touch contact with a wall decreased sway during static standing but did not influence the EMG activity of the soleus muscle.

Influence of trunk muscle co-contraction on spinal curvature during sitting cross-legged

In Asia, many activities of daily living (ADL) are performed while sitting cross-legged on the floor. This sitting posture rotates the pelvis in a more dorsal direction and lumbar lordosis is more flattened than while sitting on a chair. Sitting cross-legged induces a greater load on the intervertebral discs and spine, especially when in a slumped position that is known to increase disc pressure even more and to aggravate chronic low back pain (CLBP). Therefore, it is very important to instruct Asian people about the correct sitting posture. In addition, it is known that co-contraction of the deep spine-stabilizing muscles enhances lumbar segmental stability and the sacroiliac joint. However, little is known about the influence of co-contraction of the trunk deep muscles on spinal curvature while sitting cross-legged on the floor. The purpose of this study was to compare EMG (electromyographic) activity of the trunk muscles while slump cross-legged sitting with that during co-contraction of the trunk muscles and to investigate how this co-contraction influences spinal curvature. Ten healthy male volunteers (21.7 +/- 2.5 years old) without CLBP participated in the study. Bipolar surface electrodes were attached to the rectus abdominis, the obliquus externus abdominis, the obliquus internus abdominis, the lower back extensor muscles (L3) and the multifidus on the right side. EMG signals were continuously recorded while slump sitting cross-legged and during co-contraction of the trunk muscles. They were amplified, band-pass filtered, digitized and stored by a data acquisition system. The average muscle activity values over the five-second sample for each sitting posture were normalized to maximal voluntary contractions (%MVC). While the subjects performed both sitting postures, the curvature of the spine was measured using a skin-surface and hand-held device, the "Spinal Mouse". More significant activities of the trunk muscles, with the exception of the rectus abdominis, were observed during co-contraction of the trunk muscles than while slump sitting cross-legged. The co-contraction of the trunk muscles resulted in significantly less thoracic and lumbar curvature and more sacral angle than while slump sitting cross-legged. The results of this study indicated that co-contraction of the trunk muscles while sitting cross-legged could bring about the correct thoracic and lumbar curvature, and effectively stabilize the lumbopelvic region, and decrease focal stress on passive structures.

Adaptive changes in control of the head while lifting ten times

We often observe when workers lift objects, they tend to move their heads upward and back. Their movement may be an efficient habit, but little is known about control of the head while lifting. Our primary aim was to investigate the hypothesis that several repetitive liftings would lead to an increase in neck extension. Fifteen healthy male volunteers (20.9 +/- 0.8 years old) were asked to lift a case 10 times without instructions about the starting posture or lifting technique. Motion data and electromyography (EMG) signals were continuously recorded. The lifting time, angles of joints, and distance between the case and the malleolus lateralis at the moment of lifting were calculated from the motion data. EMG signals of the initial 1/10 phase of each lifting time were averaged and normalized to maximal voluntary contractions(% AEMG), and the mean frequencies were calculated by wavelet transform analysis. One-way analysis of variance and post hoc analysis were performed with Dunnett's test (p < 0.05). The cervical extension angle significantly increased, and the distance between the case and the malleolus lateralis significantly decreased for the later lifting times. The % AEMG of the gluteus maximus and the biceps femoris significantly increased for the later lifting times. A moving upward and back of the weight of the head, a decrease in the distance between the body and the case, and increases in tension of the hip extensor muscles could facilitate a righting movement to maintain balance. Therefore, paying attention to head control may be efficient while lifting.

Influence of trunk muscle co-contraction on spinal curvature during sitting reclining against the backrest of a chair

Today, many office workers frequently adopt a relaxed or slumped sitting posture for many hours, and often people tend to spend their leisure time reclining against the backrest of a chair while sitting for a long time, as when watching television. While sitting, the pelvis rotates backwardly, and lumbar lordosis is flattened. Simultaneously, the load on the intervertebral discs and spine increases. Sitting in a slumped position is known to increase disc pressure even more, and to aggravate chronic low back pain (CLBP). Therefore, it is very important to teach workers and often people about the correct sitting posture. In addition, it has been recognized that co-contraction of the deep spine-stabilizing muscles enhances lumbar segmental stability and the sacro-iliac joint. However, little is known about the influence of co-contraction of the trunk deep muscles on spinal curvature during sitting reclining against the backrest of a chair. The purpose of this study was to compare the EMG (electromyographic) activity of the trunk muscles during slump sitting with that during co-contraction and to investigate how this cocontraction influences spinal curvature. Ten healthy male volunteers (20.8 +/- 0.8 years old) without CLBP participated in the study. Bipolar surface electrodes were attached to the rectus abdominis, the obliquus externus abdominis, the obliquus internus abdominis, the lower back extensor muscles (L3) and the multifidus on the right side. The EMG signals were continuously recorded during slump sitting and co-contraction of the trunk muscles, reclining against the backrest of chair. They were amplified, band-pass filtered, digitized and stored by a data acquisition system. The average muscle activity values over the five-second sample for each sitting posture were normalized to maximal voluntary contractions (%MVC). While the subjects performed both sitting postures, the curvature of the spine was measured using a new skin-surface and hand-held device, the "Spinal Mouse". More significant activities of the trunk muscles, with the exception of the rectus abdominis and the lower back extensor muscles (L3), were observed during co-contraction of the trunk muscles than during slump sitting. The co-contraction of the trunk muscles resulted in significantly less lumbar curvature and more sacral angle than during slump sitting. The thoracic curvature showed no significant change during either sitting posture. The results of this study indicated that co-contraction of the trunk muscles during sitting reclining against the backrest of a chair could bring about the correct lumbar curvature, effectively stabilize the lumbopelvic region, and decrease focal stress on passive structures.

Influences of the position of the head on posture while lifting

In clinical training of some lower back pain patients, teaching them to control their lumbar lordosis during lifting may be difficult. Therefore, another effective method for lifting technique is required. In standing, head cannot move without some compensating postural adjustment. The purpose of this study was to examine the influence of head position on lifting posture. Fourteen healthy male volunteers (22.6 +/- 4.4 years old) lifted a case while maintaining two different head positions; a downward position and an upright position. In the upright position, activities of the latissimus dorsi and vastus lateralis significantly increased, and these of the biceps femoris significantly decreased during the initial 100 msec phase of lifting. There were no differences in the activities of the upper trapezius, lumbar extensor muscles (L3, L5), and obliquus abdominis under the two conditions. There were also no differences in the lumbar angle when the case was lifted. The flexion angles of the hip, knee, and ankle significantly increased, and the lumbar spine moved closer to the case. Lifting posture was influenced by the head position. Advantages included being able to shift loads on the body from the lower back to the legs, to move the lumbar spine closer to the case, and to relatively increase the moment of lumbar extension. The weight of the head as it moved upward and back, and the weight of the rear part of the body as it moved downward and forward helped to maintain balance.

Influence of trunk muscle co-contraction on spinal curvature during sitting for desk work

Nowadays, a lot of office workers are forced to sit at a desk for many hours while doing their jobs. While sitting, the pelvis rotates backwardly, and lumbar lordosis is flattened. At the same time, the load on the intervertebral discs and spine increases. Sitting in a slumped position is known to increase disc pressure even more, and to aggravate chronic low back pain (CLBP). Therefore, it is very important to teach workers about the correct sitting posture. In addition, it has been recognized that co-contraction of the deep spine-stabilizing muscles enhances lumbar segmental stability and the sacro-iliac joint. However, little is known about the influence of co-contraction of the trunk deep muscles on spinal curvature during sitting for while doing desk work. The purpose of this study was to compare EMG (electromyographic) activity of the trunk muscles during slump sitting with that during co-contraction of the trunk muscles and to investigate how this co-contraction influences spinal curvature. Ten healthy male volunteers (21.7 +/- 2.5 years old) without CLBP participated in the study. Bipolar surface electrodes were attached to the rectus abdominis, the obliquus externus abdominis, the obliquus internus abdominis, the lower back extensor muscles (L3) and the multifidus on the right side. EMG signals were continuously recorded during slump sitting and co-contraction of the trunk muscles, simulating a desk work sitting posture; i.e., slightly inclined forward. They were amplified, band-pass filtered, digitized and stored by a data acquisition system. The average muscle activity values over the five-second sample for each sitting posture were normalized to maximal voluntary contractions (%MVC). While the subjects performed both sitting postures, the curvature of the spine was measured using a new skin-surface and hand-held device, the "Spinal Mouse". More significant activities of the trunk muscles, with the exception of the rectus abdominis, were observed during co-contraction of the trunk muscles than during slump sitting The co-contraction of the trunk muscles resulted in significantly less lumbar curvature and more sacral angle than during slump sitting. The thoracic curvature showed no significant change during either sitting posture. The results of this study indicated that co-contraction of the trunk muscles during sitting while doing desk work could bring about the correct lumbar curvature, and effectively stabilize the lumbopelvic region, and decrease focal stress on passive structures.

Electromyographic activity of selected trunk muscles during bicycle ergometer exercise and walking

Recently, active treatment such as exercise has been increasingly advocated for CLBP (chronic low back pain). Specially, exercise to improve fitness has been recommended for the prevention of back injuries. The bicycle ergometer or walking have often been used to improve the fitness of CLBP patients. However, little is known about the activity levels of the trunk muscles during such exercise. In this study, the electromyographic (EMG) activities of the trunk muscles during bicycle ergometer exercises and walking were compared and the load level on these muscles during such exercises was investigated. The present study provides basic information concerning fitness exercise in CLBP patients. Eleven healthy male volunteers (21.7 +/- 2.5 years old) without low back pain participated in the study. Bipolar surface electrodes were attached to the right side of the rectus abdominis, the obliquus externus abdominis and lower back extensor muscles (L3). EMG signals were continuously recorded while walking and during gradual loading exercises and normalized to maximal voluntary contractions (% MVC). One way analysis of variance (ANOVA) was performed on the % MVC from each exercise and walking for each of the three trunk muscle sites (p < 0.05). The rectus abdominis muscle showed activity of about 6% MVC during any grade of exercise and walking and no significant differences were found between these forms of exercise. The obliquus externus abdominis muscle showed about 30% MVC during any grade of exercise and walking, but no significant difference was found between them. The low back muscles showed activity of about 12% MVC while walking, whereas activity level increased as the exercise load using the bicycle ergometer increased. More significant low back muscles activity was observed while walking than during exercises of 25 w and 50 w. The results of this study indicated that exercise using the bicycle ergometer should be useful for maintaining or improving fitness in CLBP patients, because it results in less load on the trunk muscles and relatively more oxygen uptake than walking.