EMG signal amplitude assessment during abdominal bracing and hollowing

Analysis of strength and electromyographic activity of lower limbs of individuals with down syndrome assisted in physiotherapy and hippotherapy

INTRODUCTION

one of the characteristics of Down Syndrome (DS) is muscle hypotonia. Different therapeutic approaches have a positive influence, between them Physiotherapy applications with different therapeutic approaches such as Hippotherapy have a positive effect on the physical health and quality of live of individuals with DS.

OBJECTIVE

to evaluate the effects of both treatments on the strength and electromyographic activity of the lower limbs of children and adolescents with DS.

METHODS

fourteen individuals, aged between 10 and 18 years, participated in two groups: Physiotherapy group (n = 5) and Hippotherapy group (n = 9). Thirty interventions were performed for each type of therapy, once a week, lasting 30 min. Pre and post-interventions, the 30-Second Chair Stand Test (30s-CST) was used to assess the strength of the lower limbs and the surface electromyography equipment (EMG 800RF) to assess the lower limb myoelectric activity.

RESULTS

there was a reduction in the post-intervention electromyographic values for both treatments (p˂0.001), with significantly less myoelectric activity in Hippotherapy compared to Physiotherapy for all evaluated muscles (p˂0.001) and a significant increase in muscle strength for the Hippotherapy, post-intervention group (p = 0.0007).

CONCLUSION

Physiotherapy and Hippotherapy are interventions that promote positive changes in the myoelectric activities of individuals with DS. However, only hippotherapy promoted an increase in strength of the lower limbs.

Spinal Muscle Thickness and Activation during Abdominal Hollowing and Bracing in CrossFit® Athletes

Exercises that improve muscle activation are essential for maintaining spinal stability and preventing low back pain. The purpose of this study was to compare the effects of abdominal hollowing and bracing on the activation of the core muscles in CrossFit® participants using ultrasound and electromyography (EMG). Twenty-four healthy adults aged 21 to 42 years old with at least two years of CrossFit® experience performed three core stability exercises (plank, side plank, bridge) with abdominal hollowing and bracing. We measured the ultrasound relative thickness of the local core muscles (transversus abdominis, internal oblique, and lumbar multifidus), and the EMG percentage of maximal voluntary contraction (MVC) of the global core muscles (rectus abdominis, external oblique, and iliocostalis lumborum). Analysis of variance tests showed that the relative thickness of the local core muscles was greater (p = 0.016) during hollowing (range from 26.8 ± 5.33 to 88.4 ± 11.9% of rest) than bracing (range from 15.9 ± 3.54 to 61.2 ± 15.9% of rest), while the EMG of the global muscles was greater (p = 0.001) in bracing (range from 24.4 ± 7.30 to 72.5 ± 9.17% of MVC) than hollowing (range from 16.4 ± 3.70 to 56.6 ± 7.65% of MVC). These results indicate that the recruitment of spinal muscles during popular exercises is achieved with both hollowing and bracing. Nevertheless, it appears that hollowing tends to recruit more of the local muscles, whilst bracing recruits more of the global muscles. The grading of the exercises varied between muscles and varied between maneuvers, especially for the surface abdominals and lumbar muscles. CrossFit® practitioners can choose to use either hollowing or bracing to activate their core muscles more selectively or more appropriately, depending on the goal and purpose of the exercise.

The Effects of Abdominal Hollowing and Bracing Maneuvers on Trunk Muscle Activity and Pelvic Rotation Angle during Leg Pull Front Pilates Exercise

Pilates methods use mats for trunk muscles stabilization exercises, and leg pull front (LPF) is one of the traditional Pilates mat exercises. Abdominal hollowing (AH) and Abdominal bracing (AB) maneuvers are recommended to stabilize the trunk muscles and prevent unwanted pelvic movement during motion. This study aimed to explore the effects of AH and AB on electromyography (EMG) activity of the trunk muscles and angle of pelvic rotation during LPF. A total of 20 healthy volunteers participated in the study. AH, AB, and without any condition (WC) were randomly performed during LPF exercise. Each was repeated three times for 5 s. The trunk muscle activities were measured using EMG and rotation of pelvis was measured using a Smart KEMA device. The activities of the transversus abdominis/obliquus internus abdominis (TrA/IO) and right obliquus externus abdominis (EO) muscles were highest in LPF-AH compared to the other conditions. Multifidus (MF) activity was significantly greater in LPF-AH and LPF-AB compared to that of without any condition. The pelvic rotation angle was significantly smaller in LPF-AB. Therefore, AH maneuver during LPF for trunk muscle stabilization exercises is suitable for selective activation of the TrA/IO, and AB maneuver during LPF is recommended for the prevention of unwanted pelvic rotation.

Validation and comparison of trunk muscle activities in male participants during exercise using an innovative device and abdominal bracing maneuvers

BACKGROUND

Abdominal bracing is effective in strengthening the trunk muscles; however, assessing performance can be challenging. We created a device for performing abdominal trunk muscle exercises. The effectiveness of this device has not yet been evaluated or comparedOBJECTIVE: We aimed to quantify muscle activity levels during exercise using our innovative device and to compare them with muscle activation during abdominal bracing maneuvers.

METHODS

This study included 10 men who performed abdominal bracing exercises and exercises using our device. We measured surface electromyogram (EMG) activities of the rectus abdominis (RA), external oblique, internal oblique (IO), and erector spinae (ES) muscles in each of the exercises. The EMG data were normalized to those recorded during maximal voluntary contraction (%EMGmax).

RESULTS

During the bracing exercise, the %EMGmax of IO was significantly higher than that of RA and ES (p< 0.05), whereas during the exercises using the device, the %EMGmax of IO was significantly higher than that of ES (p< 0.05). No significant difference was observed in the %EMGmax of any muscle between bracing exercises and the exercises using the device (p= 0.13-0.95).

CONCLUSIONS

The use of our innovative device results in comparable activation to that observed during abdominal bracing.

Electromyography analysis: Comparison of maximum voluntary contraction exercises for the latissimus dorsi

BACKGROUND: A prerequisite for interpreting electromyography (EMG) data is to normalize them to a maximum voluntary contraction (MVC), expressing them as percentage of the MVC. OBJECTIVE: The objective of this study was to compare different recommended MVC exercises for the latissimus dorsi and identify the exercise that elicits the highest EMG amplitude. METHODS: Fifteen male participants were recruited. Five recommended MVC exercises were investigated, including chest-supported shoulder extension, prone shoulder extension, lat-pull down, abducted shoulder flexion, and internal shoulder rotation. RESULTS: Chest-supported shoulder extension reported the highest mean EMG, which was not significantly different from the mean EMG of prone shoulder extension. Both of these exercises led to significantly greater EMG means than the other exercises. Sixty percent of the participants achieved their highest EMG amplitude with chest-supported shoulder extension and 40% with prone shoulder extension. None of the other exercises elicited the highest EMG amplitude in any of the participants. CONCLUSIONS: Both chest-supported shoulder extension and prone shoulder extension proved to be effective MVC exercises, with the former showing more consistency in eliciting the highest EMG amplitude. If the true MVC is desired, the authors recommend performing both exercises and then using the overall highest EMG amplitude for normalization purposes.

Submaximal contractions can serve as a reliable technique for shoulder electromyography normalization

There are a number of ways to normalize electromyographical data, the most common of which is using a maximal contraction as a reference. However, this technique is not always practical. The purpose of the present study was to assess the reliability of an electromyographical data normalization technique using standardized submaximal contractions. Twenty healthy subjects (ten male, ten female) were used for testing, which was performed using both surface and fine-wire electromyography over two sessions at 15, 30, 45, and 60 percent of the day 1 maximum force. There was a mean of 5.3 days between test days. Data were compared between days, and the resulting ICC and standard error of the measurement values indicate varying levels of reliability at each submaximal percent. All heads of the deltoid, the upper trapezius and the serratus anterior demonstrated good reliability for at least one submaximal condition. The latissimus dorsi and supraspinatus demonstrated moderate reliability for at least one submaximal condition. Finally, the infraspinatus demonstrated poor reliability under all conditions. For situations in which MVC is impractical or anticipated to change, EMG amplitude normalization to one of these submaximal percentages appears to be a viable technique, at least for most muscles.

The effects of abdominal hollowing and bracing on abdominal muscle thicknesses and pelvic rotation during active straight leg raise

BACKGROUND: Active straight leg-raise (ASLR) is often performed to strengthen abdominal muscles. The correct execution and maximum benefit of the ASLR can be achieved using abdominal hollowing (AH) and abdominal bracing (AB) exercises. OBJECTIVE: To compare the effects of AH and AB on transverse abdominis (TrA), internal oblique (IO), and external oblique (EO) thicknesses, as well as on the pelvic rotation angle, in healthy women during active ASLR. METHODS: The participants in this study were assigned randomly to either the AH (n= 15) or AB groups (n= 15). During ASLR, abdominal muscle thickness was measured using ultrasound and pelvic rotation was measured using a Smart KEMA device. Each trial was repeated three times for 5 s each. RESULTS: The thickness of the TrA was significantly greater during ASLR with AH than during ASLR with AB (p< 0.001). In contrast, there was no respective significant change in the thickness of the EO (p> 0.311) or IO (p> 0.818). Pelvic rotation angle was significantly reduced during ASLR with AB, compared with ASLR with AH (p< 0.018). CONCLUSIONS: We recommend that AH be performed for the selective contraction of TrA during ASLR, and that AB be performed for the prevention of the pelvic rotation during ASLR. Therefore, AH and AB should be separately done in stabilization exercises.

Influence of Anterior-Posterior External Surface Perturbation on Trunk Stability During Abdominal Stabilization Strategies While Sitting

Background

Spinal and pelvic injuries during an unexpected perturbation are closely related to spinal stability, which is known to be controlled by abdominal stabilization maneuvers. This study aimed to evaluate the effects of unexpected perturbations on trunk stability and abdominal stabilization strategies in 42 sedentary adults while sitting.

Material/Methods

Abdominal stabilization strategies consisted of bracing and hollowing maneuvers. Abdominal bracing maneuvers (ABM) were focused on the abdominal wall muscles [inferior oblique (IO), exterior oblique (EO)], and abdominal hollowing maneuvers (AHM) were focused on deep muscle (TrA) activation. The subjects were instructed in abdominal stabilization maneuvers. Afterward, subjects were seated in a chair that could be moved forward or backward suddenly with the support surface.

Results

Angular displacements of the upper thorax, lower thorax, and lumbopelvic during unexpected perturbation, with different abdominal stabilization maneuvers, were measured. During forward perturbation (d=0.71, F=10.324, P=0.001) and backward perturbation in high speed (d=0.62, F=9.265, P=0.011), there were significant differences in angular displacements of the upper thorax between hollowing and bracing maneuvers. Additionally, significant differences were found in the lumbopelvic angular displacement between the hollowing and bracing maneuvers (d=0.62, F=4.071, P=0.044).

Conclusions

Our findings indicate that the ABM is a better stabilizing technique for the upper thorax, and the AHM is a better stabilizing technique for the lumbopelvic region during unexpected perturbations at high speed in the seated position.

Analysis of phase detects altered timing of muscle activation in subjects with chronic shoulder pain

Optimal exercise therapy for shoulder pain is unknown due to limited information regarding specific changes in muscle function associated with pain. Timing of muscle activity with respect to movement (phase) can provide information about muscle activation patterns without requiring electromyography data normalization which is problematic in the presence of pain. The aim of this study was to determine if a phase measure is able to detect differences in the timing of shoulder muscle activation in subjects with chronic shoulder pain. Fourteen subjects with pain and 14 without pain were recruited. Electromyography from eight shoulder muscles was recorded. Approximately 20 cycles of small amplitude (∼30°) rapid shoulder flexion/extension was performed. A cross-correlation and spectrographic analysis provided a measure of phase. Welch's t-tests were used to compare mean phase angles between groups. Subjects with chronic shoulder pain had greater variability in the relative timing of muscle activation with significant differences found in the phase angles for pectoralis major, infraspinatus, supraspinatus, upper and lower trapezius and serratus anterior. This preliminary study indicates that the examination of the timing of muscle activation using a phase measure can identify significant differences in muscle function between normal subjects and those with chronic shoulder pain.

Electromyographic analysis of stomatognathic muscles in elderly after hippotherapy

The aging process affects the entire human body, including the stomatognathic system, and can trigger not only occlusal but also postural imbalances involving other muscular chains. Hippotherapy has been used to promote cervical, postural, and balance control in individuals with diverse impairments. The present study used electromyography to evaluate the masseter and temporal muscles in an elderly population pre- and post-hippotherapy. Participants included 17 individuals, mean age 66,5±7 years. Electromyographic recording of the bilateral masseter and temporal muscles was performed during the postural resting condition and activities that involved the active participation of these muscles in different conditions. The practitioner performed no other type of activity or exercise during the intervention because the objective is to evaluate the effect of the three-dimensional movement provided by the horse. Raw electromyographic data were tabulated using commercially available software (IBM® SPSS® Statistics 234.0) and subjected to statistical analysis, in which p ≤ 0.05 was considered to be statistically significant. Post-hippotherapy, there was lower electromyographic activity for the masseter and temporalis muscles in all the static mandibular tasks, with significant effect for time for the right temporal muscle (p = 0.038), the left temporal muscle (p = 0.028) and in the all dynamic mandibular tasks for the left temporal muscle (p = 0.025) and the left masseter muscle (p = 0.027). Hippotherapy promotes a reduction in the myoelectric activity of the masticatory muscles of elderly individuals.

Effects of myofascial release in erector spinae myoelectric activity and lumbar spine kinematics in non-specific chronic low back pain: Randomized controlled trial

BACKGROUND

Flexion-relaxation response of the lumbar erector spinae has been previously studied after different interventions such as exercise programs or spinal manipulation, in subjects with chronic low back pain. The objective of the study was to investigate the effects of an isolated myofascial release protocol on erector spinae myoelectric activity and lumbar spine kinematics in chronic low back pain.

METHODS

Thirty-six participants, with nonspecific chronic low back pain, were randomized to myofascial release group (n = 18) receiving four sessions of myofascial treatment, each lasting 40 min, and to control group (n = 18) receiving a sham myofascial release. Electromyographic and kinematic variables as well as pain and disability questionnaires were analyzed.

FINDINGS

There was a bilateral reduction of the flexion relaxation ratio in individuals receiving myofascial release and who did not show myoelectric silence at baseline (right difference M = 0.34, 95% CI [0.16, 0.33], p ≤ .05 and left difference M = 0.45, 95% CI [0.16, 0.73], p ≤ .05). There was also a significant reduction in pain in the myofascial release group (difference M = -9.1, 95% CI [-16.3, -1.8], p ≤ .05) and disability (difference M = -5.6, 95% CI [-9.1, -2.1], p ≤ .05), compared with control group. No significant differences between groups were found for the kinematic variables.

INTERPRETATION

The myofascial release protocol contributed to the normalization of the flexion- relaxation response in individuals who did not show myoelectric silence before the intervention, and also showed a significant reduction in pain and disability compared with the sham group.

Effects of unstable shoes on trunk muscle activity in patients with chronic low back pain

INTRODUCTION

Unstable shoes were developed as a walking device to strengthen the lower extremity muscles and reduce joint loading. Many studies have reported increased muscle activity throughout the gait cycle in most of the lower limb muscles in healthy adults using these shoes. However, no previous studies have explored the effects of wearing unstable shoes on trunk muscle activity in patients with chronic low back pain (CLBP). Therefore, the aim of the present study was to compare the activity of selected trunk muscles in patients with CLBP during a gait test while walking wearing unstable shoes or conventional flat shoes (control).

METHODS

Thirty-five CLBP patients (51.1 ± 12.4 y; 26 ± 3.8 kg/m2; 9.3 ± 5.2 Roland Morris Disability Questionnaire score) were recruited from the Orthopedic Surgery Service at the Hospital to participate in this cross-sectional study. All the participants underwent gait analysis by simultaneously collecting surface electromyography (EMG) data from erector spinae (ES), rectus abdominis (RA), obliquus internus (OI), and obliquus externus (OE) muscles, while walking on a treadmill with flat control shoes or experimental unstable shoes.

RESULTS

The results showed significantly higher %EMG activity in the ES (mean difference: 1.8%; 95% CI: 1.3-2.2), RA (mean difference: 1.5%; 95% CI: 0.3-2.7), and OI (mean difference: 1.5%; 95% CI: 0.2-2.8) in the unstable versus the flat-shoe condition, with a large effect size for the ES (Cohen's d = 1.27).

CONCLUSIONS

Based on these findings, the use of unstable shoes may be implicated in promoting spine stability, particularly in improving neuromuscular control of the trunk muscles in CLBP treatment.

Reliability of surface electromyography activity of gluteal and hamstring muscles during sub-maximal and maximal voluntary isometric contractions

BACKGROUND

Normalizing to a reference signal is essential when analysing and comparing electromyography signals across or within individuals. However, studies have shown that MVC testing may not be as reliable in persons with acute and chronic pain.

OBJECTIVES

The purpose of this study was to compare the test-retest reliability of the muscle activity in the biceps femoris and gluteus maximus between a novel sub-MVC and standard MVC protocols.

METHODS

This study utilized a single individual repeated measures design with 12 participants performing multiple trials of both the sub-MVC and MVC tasks on two separate days. The participant position in the prone leg raise task was standardised with an ultrasonic sensor to improve task precession between trials/days. Day-to-day and trial-to-trial reliability of the maximal muscle activity was examined using ICC and SEM.

FINDINGS

Day-to-day and trial-to-trial reliability of the EMG activity in the BF and GM were high (0.70-0.89) to very high (≥0.90) for both test procedures. %SEM was <5-10% for both tests on a given day but higher in the day-to-day comparisons. The lower amplitude of the sub-MVC is a likely contributor to increased %SEM (8-13%) in the day-to-day comparison.

CONCLUSIONS

The findings show that the sub-MVC modified prone double leg raise results in GM and BF EMG measures similar in reliability and precision to the standard MVC tasks. Therefore, the modified prone double leg raise may be a useful substitute for traditional MVC testing for normalizing EMG signals of the BF and GM.

Development of a pressure sensor system for unobtrusive monitoring of abdominal muscle activities

Surface electromyogram (sEMG) is often used by to objectively measure muscular activity during rehabilitation exercises. sEMG is accurate, but it is unsuitable for uses outside the clinic, and patients can benefit from an unobtrusive device which can be readily used to ubiquitously measure abdominal muscle activation. In this study, we present a pressure sensor system which can be latched onto a belt to measure abdominal muscle activation. sEMG and pressure sensor output were measured in 15 healthy young males during isometric trunk flexion exercise (public trials registration number, KCT0002351), and the results were highly correlated (median R > 0.939). As initial contact force can change the pressure sensor sensitivity, the experiment was performed at two different levels of belt tightness, but the correlations did not significantly improve after tightening the belt, suggesting that the system can be used to ubiquitously and unobtrusively monitor abdominal muscle activity with minimal discomfort.

EMG normalization method based on grade 3 of manual muscle testing: Within- and between-day reliability of normalization tasks and application to gait analysis

Electromyography (EMG) is an important parameter in Clinical Gait Analysis (CGA), and is generally interpreted with timing of activation. EMG amplitude comparisons between individuals, muscles or days need normalization. There is no consensus on existing methods. The gold standard, maximum voluntary isometric contraction (MVIC), is not adapted to pathological populations because patients are often unable to perform an MVIC. The normalization method inspired by the isometric grade 3 of manual muscle testing (isoMMT3), which is the ability of a muscle to maintain a position against gravity, could be an interesting alternative. The aim of this study was to evaluate the within- and between-day reliability of the isoMMT3 EMG normalizing method during gait compared with the conventional MVIC method. Lower limb muscles EMG (gluteus medius, rectus femoris, tibialis anterior, semitendinosus) were recorded bilaterally in nine healthy participants (five males, aged 29.7±6.2years, BMI 22.7±3.3kgm^-2) giving a total of 18 independent legs. Three repeated measurements of the isoMMT3 and MVIC exercises were performed with an EMG recording. EMG amplitude of the muscles during gait was normalized by these two methods. This protocol was repeated one week later. Within- and between-day reliability of normalization tasks were similar for isoMMT3 and MVIC methods. Within- and between-day reliability of gait EMG normalized by isoMMT3 was higher than with MVIC normalization. These results indicate that EMG normalization using isoMMT3 is a reliable method with no special equipment needed and will support CGA interpretation. The next step will be to evaluate this method in pathological populations.

Effects and underlying mechanisms of unstable shoes on chronic low back pain: a randomized controlled trial

OBJECTIVE

To investigate the effects that wearing unstable shoes has on disability, trunk muscle activity, and lumbar spine range of motion (ROM) in patients with chronic lower back pain (CLBP).

DESIGN

Randomized controlled trial.

SETTING

Orthopedic Surgery Service.

PARTICIPANTS

We randomized 40 adults with nonspecific CLBP either to an unstable shoes group ( n = 20) or to the control group ( n = 20).

INTERVENTION

The participants in the unstable shoes group were advised to wear these shoes for a minimum of six hours a day for four weeks. Control group participants were asked to continue wearing their regular shoes.

OUTCOME MEASURES

Our primary outcome was measurement of back-related dysfunction, assessed using the Roland-Morris Disability Questionnaire. Secondary outcomes included changes in electromyographic (EMG) activity of erector spinae (ES), rectus abdominis (RA), internus obliquus (IO), and externus obliquus (EO) muscles, and changes in lumbar spine ROM.

RESULTS

Between-group analysis highlighted a significant decrease in disability in the unstable shoes group compared to the control (-5, 95% confidence interval (CI) = -8.4 to -1.6). Our results revealed a significant increase in the percentage of RA, ES, IO, and EO EMG activity and in lumbar spine ROM in the unstable shoes group compared to the control group. Moreover, our results showed a significant negative correlation between disability and the percentage of ES, RA, and IO muscle activity at the end of the intervention.

CONCLUSION

This study shows that the use of unstable shoes contributes to improvements in disability, which are likely related to increased trunk muscle activity and lumbar spine ROM.

Normalization of the trapezius sEMG signal - a reliability study on women with and without neck-shoulder pain

Objective

To evaluate within- and between-days reliability of two normalization methods of surface electromyography (sEMG) recordings of the trapezius muscle.

Methods

Nineteen women were allocated into 2 groups (healthy and with neck-shoulder pain). The sEMG was recorded in two sessions with 7 days in between sessions. The four portions of the trapezius muscle (the clavicular and acromial fibers of the upper trapezius, the middle and the lower trapezius) were evaluated during maximal and submaximal isometric voluntary contractions. The within- and between-days reliability of both maximal and submaximal contractions were assessed through Intraclass Correlation Coefficient (ICC_(2,1) was used for within-day analyses of both maximal and submaximal contractions, and for between-days analyses of maximal contractions while ICC_(2,3) was used for between-days analyses of submaximal contractions), Coefficient of Variation, Standard Error of Measurement, and Bland–Altman analysis.

Results

In general, submaximal contractions presented higher within-day reliability, with higher ICC values (e.g., middle trapezius – mean of 0.97), smaller Coefficient of Variation and Standard Error of Measurement ranges compared to maximal contractions (ICC values, e.g. for middle trapezius – mean of 0.94) in both groups. The same pattern was observed for between-days analyses, with submaximal contractions presenting higher ICC values (e.g., middle trapezius – mean of 0.84), smaller Coefficient of Variation and Standard Error of Measurement ranges than maximal contractions (ICC values, e.g. for middle trapezius – mean of 0.73) in both groups.

Conclusion

Submaximal contractions are recommended for normalization procedures of trapezius sEMG, in both subjects with neck-shoulder pain and healthy individuals.

Precision based guidelines for sub-maximal normalisation task selection for trunk extensor EMG

AIM

The object of this study was to quantify the contribution of sub-maximal normalisation to the overall variance of exposure parameters describing erector spinae (ES) activity, and to provide guidelines for task selection which minimize methodological variance.

METHODS

ES EMG was measured from three locations (T9, L1 and L5 levels) on fifteen men performing a manual materials handling task in the laboratory on three separate days. Four repeats of each of eleven sub-maximal normalisation tasks (eight static, three dynamic) were collected, work data were normalised to each task and repeat, and exposure parameters calculated. The unique contribution of normalisation to the overall variance was determined for each task and exposure parameter using variance component analyses. Normalisation tasks were scored according to their relative contributions to the overall variance and coefficients of variation.

RESULTS

A prone task, similar to the Biering-Sørensen test posture, was the most repeatable for all electrode locations and across all exposure parameters. Thoracic level normalisation typically showed poorer repeatability than lumbar normalisation.

DISCUSSION

To maximize measurement precision, we recommend that future ES EMG studies employing sub-maximal normalisation utilise said prone task. An alternate normalisation task specific to thoracic level ES muscles may be warranted.

Female Age-Related Differences in Biomechanics and Muscle Activity During Descents on the Outstretched Arms

The purposes of this study were to examine female age differences in: (1) upper extremity (UE) and trunk muscle activity, elbow joint moment, loading force, and UE energy absorption during a controlled forward body descent; and (2) UE muscle strength. Twenty young (mean 24.8 ± 3.4 years) and 20 older (68.4 ± 5.7 years) women were assessed via dynamometry for isometric, concentric, and eccentric UE strength and performed forward descents on force plates at three body lean angles (60°, 45°, and 30° from horizontal). Significant differences (p < .05) were found for muscle strength, biomechanics, and muscle activity. Concentric UE strength averaged 15% lower in older women. At 30° body lean, older women absorbed less energy. Older women had greater biceps brachii activation and less external oblique activation at all body lean angles. Age differences in muscle strength, activation, and energy absorption may contribute to fall-related injury risk.

The effects of upper extremity task training with symmetric abdominal muscle contraction on trunk stability and balance in chronic stroke patients

[Purpose] The purpose of this study is to examine the effects of upper extremity task training employing the bracing method on the trunk control and balance of stroke patients. [Subjects and Methods] The subjects were 46 stroke patients whose strokes had occurred six months or more prior to the study. The subjects were divided into two groups. One group underwent upper extremity task training with symmetric abdominal muscle contraction (bracing) applied. The other group simply underwent upper extremity task training, without bracing. [Results] The experimental group’s Trunk Impairment Scale (TIS) significantly increased after the intervention, whereas the control group did not see any significant difference. There was significant improvement in balance after the intervention in both the experimental group and the control group. According to the between-group comparisons, the improvements in the experimental group were significantly greater in the control group, except in the Postural Assessment Scale (PASS). [Conclusion] Based on the results of this study, upper extremity task exercises with symmetric abdominal muscle contraction, conducted as part of adult hemiplegic patients’ trunk stabilization exercises, can be applied to a diverse range of hemiplegic patients and implemented as an exercise program after discharge from hospital.

Relationship between flexion-rotation test and ultrasound thickness measurement of the abdominal muscles

OBJECTIVE

The purpose of this study was to investigate the relationship between flexion-rotation test and ultrasound (US) thickness measurement of the antero-lateral abdominal muscles.

DESIGN

Following ethical approval, a convenience sample of 55 subjects between the ages of 20 and 30 years participated in this study. Endurance of the abdominal muscles was measured using the flexion-rotation test in all subjects. US thickness measurement for the transversus abdominis (TrA), internal oblique (IO) and external oblique (EO) muscles was performed on the right side at rest in a supine position.

RESULTS

Pearson correlation coefficient between the variables of the study showed no significant relationship between the flexion-rotation test and US thickness measurements of the TrA (r = -0.03, P = 0.80), IO (r = -0.13, P = 0.32), and EO (r = -0.14, P = 0.31) muscles. The significance level of 0.05 was chosen.

CONCLUSION

It seems that there is no significant relationship between the flexion-rotation test and US measurement of abdominal muscles thickness.

sEMG ACTIVITIES OF THE THREE HEADS OF THE TRICEPS BRACHII MUSCLE DURING CRICKET BOWLING

The aim of the present study was to analyze the surface electromyography (sEMG) activities generated by the three heads of the triceps brachii (TB) muscle among the different phases during fast and spin bowling. sEMG signals from the lateral, long and medial heads of the TB from 20 bowlers were measured individually during bowling. To analyze the sEMG activities, the root mean square (RMS) value in each bowling phase for every trial per bowler was calculated from the sEMG signals from the three heads of the TB. Higher sEMG activities at the three heads of the TB were found during the fifth phase followed by the sixth, seventh, third, fourth, second and first phases in both types of bowling. sEMG activities were significantly different among the three heads of the TB and among the seven bowling phases for both bowling types at an alpha level of [Formula: see text]. These findings will be of particular importance for assessing different physical therapies for the three headed TB muscle which can improve the performance in ball delivery of cricket bowlers.

Comparison of the Effects of Hollowing and Bracing Exercises on Cross-sectional Areas of Abdominal Muscles in Middle-aged Women

[Purpose] The purpose of this study was to examine the effects of hollowing and bracing exercises on cross-sectional areas of abdominal muscles. [Subjects] Thirty healthy female adults participated in this study. The exclusion criteria were orthopedic or neurologic diseases. [Methods] The subjects of this study were assigned randomly to one of two groups, each with 15 people. Each group performed a 60-minute exercise program, one performed a bracing exercise, and the other performed a hollowing exercise, with both groups performing the exercise three times a week for six weeks. [Results] The changes in cross-sectional areas after the bracing exercise showed statistically significant differences in the left rectus abdominis and both internal and external obliques. The changes in cross-sectional areas after the hollowing exercise showed statistically significant differences in the left and right transversus abdominis and left rectus abdominis. [Conclusion] Performing bracing exercises rather than hollowing exercises is more effective for activating the abdominal muscles.

The effect of abdominal bracing in combination with low extremity movements on changes in thickness of abdominal muscles and lumbar strength for low back pain

[Purpose] The purpose of this study was to investigate the effects of abdominal bracing with low extremity movement on changes in thickness of abdominal muscles and lumbar strength. [Subjects] Sixteen patients with chronic low back pain were randomly assigned to two groups: an abdominal bracing with active straight leg raise (ABSLR) group and abdominal bracing with ankle dorsiflexion (ABDF) group. [Methods] All subjects were evaluated for their abdominal muscle strength using a MedX Lumbar Extension Machine and thickness of external oblique (EO), internal oblique (IO), and transverse abdominis (TrA) muscles using rehabilitative ultrasound imaging. Subjects in both groups were instructed to perform Abdominal bracing (AB). Simultaneously, those in the ABSLR group performed active SLR, and those in the ABDF group performed ankle dorsiflexion. [Results] In comparison between the ABSLR and ABDF groups, significant differences in the thickness of the IO and TrA muscles were observed after the intervention in the ABSLR group. Also, lumbar strength was showed a significant increase in both groups after interventions. [Conclusion] The results of this study demonstrated that ABSLR is a more effective method than ABDF for improvement of abdominal stabilization by increasing the thicknesses of the TrA and IO.

Surface electromyographic analysis of the biceps brachii muscle of cricket bowlers during bowling

Cricket bowling generates forces with torques on the upper limb muscles and makes the biceps brachii (BB) muscle vulnerable to overuse injury. The aim of this study was to investigate whether there are differences in the amplitude of the EMG signal of the BB muscle during fast and spin delivery, during the seven phases of both types of bowling and the kinesiological interpretation of the bowling arm for muscle contraction mechanisms during bowling. A group of 16 male amateur bowlers participated in this study, among them 8 fast bowlers (FB) and 8 spin bowlers (SB). The root mean square (EMGRMS), the average sEMG (EMGAVG), the maximum peak amplitude (EMGpeak), and the variability of the signal were calculated using the coefficient of variance (EMGCV) from the BB muscle of each bowler (FB and SB) during each bowling phase. The results demonstrate that, (i) the BB muscle is more active during FB than during SB, (ii) the point of ball release and follow-through generated higher signals than the other five movements during both bowling categories, (iii) the BB muscle variability is higher during SB compared with FB, (iv) four statistically significant differences (p<0.05) found between the bowling phases in fast bowling and three in spin bowling, and (v) several arm mechanics occurred for muscle contraction. There are possible clinical significances from the outcomes; like, recurring dynamic contractions on BB muscle can facilitate to clarify the maximum occurrence of shoulder pain as well as biceps tendonitis those are medically observed in professional cricket bowlers, and treatment methods with specific injury prevention programmes should focus on the different bowling phases with the maximum muscle effect. Finally, these considerations will be of particular importance in assessing different physical therapy on bowler's muscle which can improve the ball delivery performance and stability of cricket bowlers.

What is a Suitable Pressure for the Abdominal Drawing-in Maneuver in the Supine Position Using a Pressure Biofeedback Unit?

[Purpose] The aim of this study was to determine the appropriate pressure variation for performing a successful abdominal drawing-in maneuver (ADIM). The abdominal muscle thickness variations and contraction ratios were examined in relation to pressure variations using a Pressure Biofeedback Unit (PBU) during an ADIM in the supine position. [Methods] The PBU was placed identically between the lumbar lordosis of 20 healthy subjects (12 males and 8 females) and the pressure of the PBU was maintained at 40 mmHg. Then, while the subjects performed ADIM at four random pressure variations (0, 2, 4, or 6 mmHg), the thicknesses of the transversus abdominis (TrA), the internal oblique abdominal muscle (IO), and the external oblique abdominal muscle (EO) were measured using ultrasonography. [Results] Pressure increases of 0-2 mmHg resulted in significant decreases in IO and EO thicknesses compared to pressure increases of 6 mmHg. Increases of 0-2 mmHg also resulted in significant decreases in IO+EO and EO contraction ratios compared to pressure increases of 6 mmHg, while the preferential activation ratio of the TrA was significantly increased. [Conclusion] Compared to the other pressure increases, an increase of 0-2 mmHg effectively regulated the thicknesses and contraction ratios of superficial muscles such as IO and EO, rather than the thickness and contraction ratio of the TrA, showing high and indirect preferential activation ratios for TrA. Therefore, for successful ADIM, rather than using large PBU pressure increases, exercises that promote slight increases of around 0-2 mmHg from a baseline of 40 mmHg are desirable.

A reliability of electromyographic normalization methods for the infraspinatus muscle in healthy subjects

The purpose of this study was to examine the test-retest reliability of normalization methods for the infraspinatus muscle in a group of healthy subjects. Twelve healthy subjects (male=8, female=4) performed the maximal voluntary isometric contraction (MVIC) with examiner`s resistance, MVIC with a digital tension-meter (MVIC-DT), and sub-MVIC methods. Surface electromyography (EMG) signals were recorded from the infraspinatus muscles according to normalization methods. Reliability was analyzed using the intra-class coefficient (ICC), standard error of measurement (SEM), and minimal detectable difference (MDD). The results of the present study demonstrated that the sub-MVIC method has excellent test-retest reliability (ICC=0.92) with a relatively small SEM (5.9 mV) and MDD₉₅ (16.4 mV), compared to MVIC-DT (ICC=0.73; SEM=11.2 mV; MDD₉₅: 31 mV) and MVIC-E (ICC=0.5; SEM=15.7 mV; MDD₉₅: 43.6 mV). These findings provide evidence that sub-MVIC is more appropriate for comparing the EMG activity for the infraspinatus muscle as a normalization method. If MVIC for normalization is needed, MVIC-DT is more appropriate than MVIC-E.

Acute effect of labile surfaces during core stability exercises in people with and without low back pain

OBJECTIVE

The purpose of this study was to measure trunk muscle activity, whole body balance, and lumbar range of motion during core stability exercises in individuals with and without low back pain (LBP) on and off a labile surface.

DESIGN

Descriptive cross-sectional study.

SETTING

University laboratory.

PARTICIPANTS

Ten individuals with chronic non-specific LBP and 10 matched control subjects.

MAIN OUTCOME MEASURES

Bilateral trunk muscle activity was measured using surface electromyography (EMG); whole body balance was measured by quantifying the dispersion of the centre of pressure (CoP); lumbar range of motion (LROM) was measured with single-axis inclinometers.

RESULTS

Individuals with LBP had adaptive recruitment patterns during the side-bridge and modified push-up exercises. CoP dispersion and LROM were not different between groups for any exercise. The labile surface did not change the difference between groups, and only increased muscle activity during the side-bridge (p<0.05). The labile surface increased LROM (p=0.35) and CoP dispersion (p<0.001) during the quadruped, decreased LROM during squats (p=0.05), and increased CoP dispersion during push-ups (p=0.04).

CONCLUSION

Individuals with LBP exhibited adaptive trunk muscle activity levels while maintaining similar levels of balance and lumbar movement to healthy controls. Since research suggests no one mode of exercise is more beneficial in LBP rehabilitation, the practicality and safety of labile surfaces for LBP exercise rehabilitation must be questioned from this study.

The effect of resisted inspiration during an active straight leg raise in pain-free subjects

Alterations of respiratory patterns have been observed in pelvic girdle pain subjects during the active straight leg raise (ASLR). This study investigated how pain-free subjects coordinate motor control during an ASLR when this task is complicated by the addition of a respiratory challenge. Trunk muscle activation, intra-abdominal pressure, intra-thoracic pressure, pelvic floor motion, downward pressure of the non-lifted leg and respiratory rate were compared between resting supine, ASLR, breathing with inspiratory resistance (IR) and ASLR+IR. Subjects responded to ASLR+IR with an increase in the motor activation in the abdominal wall and chest wall compared to when ASLR and IR were performed in isolation. Activation of obliquus internus abdominis was greater on the side of the leg lift during the ASLR+IR, in comparison to symmetrical activation observed in the other abdominal wall muscles. The incremental increase of motor activity was associated with greater intra-abdominal pressure baseline shift when lifting the leg during ASLR+IR compared to ASLR. Individual variation was apparent in the form of the motor control patterns, mostly reflected in variable respiratory activation of the abdominal wall. The findings highlight the flexibility of the neuromuscular system in adapting to simultaneous respiratory and stability demands.

MVC techniques to normalize trunk muscle EMG in healthy women

Normalization of the surface electromyogram (EMG) addresses some of the inherent inter-subject and inter-muscular variability of this signal to enable comparison between muscles and people. The aim of this study was to evaluate the effectiveness of several maximal voluntary isometric contraction (MVC) strategies, and identify maximum electromyographic reference values used for normalizing trunk muscle activity. Eight healthy women performed 11 MVC techniques, including trials in which thorax motion was resisted, trials in which pelvis motion was resisted, shoulder rotation and adduction, and un-resisted MVC maneuvers (maximal abdominal hollowing and maximal abdominal bracing). EMG signals were bilaterally collected from upper and lower rectus abdominis, lateral and medial aspects of external oblique, internal oblique, latissimus dorsi, and erector spinae at T9 and L5. A 0.5s moving average window was used to calculate the maximum EMG amplitude of each muscle for each MVC technique. A great inter-subject variability between participants was observed as to which MVC strategy elicited the greatest muscular activity, especially for the oblique abdominals and latissimus dorsi. Since no single test was superior for obtaining maximum electrical activity, it appears that several upper and lower trunk MVC techniques should be performed for EMG normalization in healthy women.

Motor control patterns during an active straight leg raise in chronic pelvic girdle pain subjects

STUDY DESIGN

Repeated measures.

OBJECTIVE

To investigate motor control (MC) patterns in chronic pelvic girdle pain (PGP) subjects during an active straight leg raise (ASLR).

SUMMARY OF BACKGROUND DATA

The ASLR is a test used to assess load transference through the pelvis. Altered MC patterns have been reported in subjects with chronic PGP during this test. These patterns may impede efficient load transfer, while having the potential to impinge on respiratory function and/or to adversely affect the control of continence.

METHODS

Twelve female subjects with chronic PGP were examined. Electromyography of the anterior abdominal wall, right chest wall and the scalene, intraabdominal pressure, intrathoracic pressure, respiratory rate, pelvic floor kinematics, and downward leg pressure of the nonlifted leg were compared between an ASLR lifting the leg on the affected side of the body versus the nonaffected side.

RESULTS

Performing an ASLR lifting the leg on the affected side of the body resulted in a predominant MC pattern of bracing through the abdominal wall and the chest wall. This was associated with increased baseline shift in intraabdominal pressure and depression of the pelvic floor when compared with an ASLR lifting the leg on the nonaffected side.

CONCLUSION

This MC pattern, identified during an ASLR on the affected side of the body, has the potential to be a primary mechanism driving ongoing pain and disability in chronic PGP subjects.