Training the cervical muscles with prescribed motor tasks does not change muscle activation during a functional activity

Both low-load and high-load training of the cervical muscles have been shown to reduce neck pain and change parameters of muscle function directly related to the exercise performed. The purpose of this study was to investigate whether either training regime changes muscle activation during a functional task which is known to be affected in people with neck pain and is not directly related to either exercise protocol. Fifty-eight female patients with chronic neck pain were randomised into one of two 6-week exercise intervention groups: an endurance-strength training regime for the cervical flexor muscles or low-load training of the cranio-cervical flexor muscles. The primary outcome was a change in electromyographic (EMG) amplitude of the sternocleidomastoid (SCM) muscle during a functional, repetitive upper limb task. At the 7th week follow-up assessment both intervention groups demonstrated a reduction in their average intensity of pain (P<0.05). However, neither training group demonstrated a change in SCM EMG amplitude during the functional task (P>0.05). The results demonstrate that training the cervical muscles with a prescribed motor task may not automatically result in improved muscle activation during a functional activity, despite a reduction in neck pain.     

Comparison of gluteus medius muscle activity during functional tasks in individuals with and without osteoarthritis of the hip joint

Background

Neuromuscular alterations have been reported for patients with osteoarthritis of the hip joint; however, the underlying cause associated with altered gluteus medius muscle function has not been examined. This study assessed electromyographic amplitudes of the gluteus medius muscles during function in patients with unilateral end-stage osteoarthritis of the hip joint compared to controls.

Methods

Patients with unilateral end-stage hip joint osteoarthritis (n = 13) and asymptomatic control participants (n = 17) participated. Average root-mean squared muscle amplitudes represented as a percent of maximum voluntary isometric contraction for both the involved and uninvolved limb gluteus medius muscles were analyzed during step up, step down, and gait. The association between muscle activation and impact forces during stepping tasks was assessed.

Findings

Patients with hip osteoarthritis exhibited increased gluteus medius muscle electromyographic amplitudes bilaterally during stair ascent, stair descent, and gait compared to controls, regardless of which limb they led. Involved limb muscle activity was inversely related to impact force during step down onto the ipsilateral limb.

Interpretation

Patients with hip osteoarthritis demonstrated increased gluteus medius muscle activation levels during stepping tasks and gait when compared to controls. The increased activation is most likely a compensatory response to muscle weakness. Therefore, application of strengthening exercises which target the gluteal muscles should assist in neuromuscular control and result in improved strength for patients with hip joint osteoarthritis.     

Correlations among trunk impairment,functional performance,and muscle activity during forward reaching tasks in patients with chronic stroke

[Purpose] This study aimed to investigate the relationships among trunk impairment, functional performance, and muscle activity during forward reaching tasks in patients with chronic stroke. [Subjects and Methods] Twenty-three chronic stroke patients participated in this study. Trunk impairment and functional performance were evaluated using the Trunk Impairment Scale, Berg Balance Scale, Timed Up and Go Test, and 10-Meter Walk Test. All subjects were asked to perform 3 different forward reaching tasks (affected side reaching, forward reaching, and less-affected side reaching), and measurements were taken during these 3 tasks by using surface electromyography. Correlation analyses were performed to assess the relationships among trunk impairment, functional performance, and muscle activity during the forward reaching tasks. [Results] Spearman’s correlation analysis revealed a strong, significant correlation between the Trunk Impairment Scale and functional performance, that was associated with balance and gait ability. During the 3 different forward reaching tasks, muscle activities of the less-affected lower extremity were significantly correlated with functional performance. [Conclusion] This study revealed the correlations among trunk impairment, functional performance, and muscle activity during forward reaching tasks in patients with chronic stroke and emphasized the importance of trunk rehabilitation.Key words: Electromyography, Postural balance, Stroke     

Analysis of proximal and distal muscle activity during handwriting tasks.

OBJECTIVE: In this study we sought to describe upper-extremity proximal and distal muscle activity in typically developing children during a handwriting task and to explore the relationship between muscle activity and speed and quality of writing. METHOD: We evaluated 35 third- and fourth-grade Israeli children using the Alef-Alef Ktav Yad Hebrew Handwriting Test. Simultaneously, we recorded the participants' upper trapezius and thumb muscle activity by surface electromyography. Using the coefficient of variation (standard deviation divided by mean amplitude) as a measure of variability within each muscle, we analyzed differences in muscle activity variability within and between muscles. RESULTS: The proximal muscle displayed significantly less variability than the distal muscles. Decreased variability in proximal muscle activity was associated with decreased variability in distal muscle activity, and decreased variability in the distal muscles was significantly associated with faster speed of writing. CONCLUSION: The lower amount of variability exhibited in the proximal muscle compared with the distal muscles seems to indicate that the proximal muscle functions as a stabilizer during a handwriting task. In addition, decreased variability in both proximal and distal muscle activity appears to be more economical and is related to faster writing speed. Knowledge of the type of proximal and distal muscle activity used during handwriting can help occupational therapists plan treatment for children with handwriting disabilities.     

An investigation into EMG activity in the upper and lower portions of the subscapularis muscle during normal shoulder motion

Background and Purpose . The subscapularis (SSc) muscle is considered to perform a variety of roles during normal shoulder movement. The SSc is innervated by two or more discrete motor nerves and previous studies have indicated some difference in electromyographic (EMG) activity between the upper and lower portions of the muscle. The purpose of the present study was to compare EMG activity between the upper and lower portions of the SSc muscle during voluntary shoulder movements in normal healthy subjects. Method . Eight subjects were evaluated. A pair of intramuscular electrodes was inserted into each portion of the muscle. EMG data were recorded during the following movements: sagittal flexion; abduction in the coronal plane; and abduction in the scapular plane. Results . EMG onset of the upper portion of subscapularis occurred significantly earlier compared to the lower portion. Differences were also seen in the level and pattern of activation between the two portions, with upper SSc demonstrating higher levels of activation than the lower portion. Conclusions . These findings suggest that the upper and lower portions of SSc are differentially active during voluntary shoulder movements. Copyright © 2006 John Wiley & Sons, Ltd.     

Characterization of upper arm synergies during reaching tasks in able-bodied and hemiparetic subjects

BACKGROUND: In the past, several studies showed the existence of a synergistic behavior between elbow and shoulder joints during reaching movements in able-bodied subjects. The aim of this paper was to characterize the modifications of upper arm synergies during reaching induced by stroke. METHODS: Ten able-bodied right-handed subjects, eight right-handed subjects with hemiparesis affecting the right (dominant) upper limb participated in the experiments. The kinematics of shoulder and elbow joints have been recorded in all the participants during selected reaching movements. From the eight-like plots characterizing the relationship between shoulder and elbow angular velocities, a topological parameter (named as C approximately ) representing the linear approximation of the synergy between the two angular velocities has been extracted. FINDINGS: The results of these experiments showed that C approximately could be used as a figure of merit for the comparison of performance in able-bodied and hemiparetic persons. The hemiparetic subjects showed a significantly higher spreading of the values of C approximately for the different reaching movements when compared with the performance of able-bodied subjects. INTERPRETATION: This work showed that hemiparesis modified upper arm synergies and could provide a protocol for the assessment of upper limb function. Moreover, important applications of this method could be found in the development of biomimetic algorithms for the control of upper extremities during reaching in humanoid robots, and in the design of customized "games" in neurorehabilitation procedures implemented by using robotic and mechatronic platforms.     

Electromyographic activity of the hip and knee muscles during functional tasks in males with and without patellofemoral pain

Background

Patellofemoral pain (PFP) is a common overuse injury in physically active individuals. It is characterized by anterior knee, retropatellar, or prepatellar pain associated with activities that increase patellofemoral joint stress such as squatting, stair ascending and descending, running, jumping, prolonged sitting, and kneeling. The etiology of PFP is believed to be multifactorial. Recently, proximal factors have been shown to influence the biomechanics of patellofemoral joint.

Improvements in kinematics,muscle activity and pain during functional tasks in females with patellofemoral pain following a single patterned electrical stimulation treatment

BackgroundIndividuals with patellofemoral pain present with altered hip muscle activation, faulty movement patterns, and pain during functional tasks. Examining new treatment options to address these impairments may better treat those with patellofemoral pain. The purpose of this study was to determine if patterned electrical stimulation to the lower extremity affects muscle activity, movement patterns, and pain following a single treatment.MethodsFifteen females with patellofemoral pain were randomized to receive a single 15-minute treatment of either a patterned electrical neuromuscular stimulation or a sham. Peak kinematics of the knee, hip, and trunk, electromyography and pain were examined pre and post-intervention during a single leg squat and lateral step-down task. Group means and pre/post reduced kinematic values were also plotted during the entire task with 90% confidence intervals to identify differences in movement strategies.FindingsNo baseline differences were found in peak kinematics between groups. No pre to post-intervention differences in peak knee, hip and trunk kinematics were found, however differences were seen when the quality of movement across the entire tasks was assessed. The electrical stimulation group had improved knee flexion and hip abduction during the lateral step-down. A significant improvement in gluteus medius activation following patterned electrical neuromuscular stimulation occurred during the step-down (P = 0.039). Significant pain improvements were also seen in both the single leg squat (P = 0.025) and lateral step-down (P = 0.006).InterpretationA single treatment of patterned electrical neuromuscular stimulation improved muscle activation, lower extremity kinematics during functional tasks, and pain.     

Brain activity during simulated deception: an event-related functional magnetic resonance study

TheGuilty Knowledge Test (GKT) has been used extensively to model deception. An association between the brain evoked response potentials and lying on the GKT suggests that deception may be associated with changes in other measures of brain activity such as regional blood flow that could be anatomically localized with event-related functional magnetic resonance imaging (fMRI). Blood oxygenation level-dependent fMRI contrasts between deceptive and truthful responses were measured with a 4 Tesla scanner in 18 participants performing the GKT and analyzed using statistical parametric mapping. Increased activity in the anterior cingulate cortex (ACC), the superior frontal gyrus (SFG), and the left premotor, motor, and anterior parietal cortex was specifically associated with deceptive responses. The results indicate that: (a) cognitive differences between deception and truth have neural correlates detectable by fMRI, (b) inhibition of the truthful response may be a basic component of intentional deception, and (c) ACC and SFG are components of the basic neural circuitry for deception.     

Lower-extremity kinematics and postural stability during stair negotiation: Effects of two cognitive tasks

Background

Concurrent cognitive tasks were found to affect gait characteristics during level walking, such as decreasing speed, cadence, step length, etc. Given that many accidents occur during stair negotiation and people often perform cognitive tasks concurrently with stair negotiation in daily life, there is a need to study how cognitive tasks affect gait characteristics and postural stability during stair negotiation. This study aimed to determine cognitive task effects on lower-extremity kinematics and postural stability during stair negotiation. We also examined the difference in cognitive demands between ascent and descent.

Methods

Two cognitive tasks, i.e. ‘backward digit recall’ and ‘counting backward in threes’, were examined. There were three testing conditions corresponding to a baseline and the two cognitive tasks, respectively. In the baseline, no cognitive task was performed. In the cognitive task conditions, the cognitive task was performed continuously throughout the stair negotiation trial. Each participant performed six ascent trials and six descent trials under each testing condition. We measured the cognitive task performance. Lower-extremity kinematics and postural stability were calculated using the data collected from a complete stair gait cycle that was obtained for the dominant leg.

Findings

In general, concurrent cognitive tasks had adverse effects on lower-extremity kinematics and postural stability during both ascent and decent. No differences in dependent measures were found between cognitive tasks. Additionally, ascent and descent appeared to be equally cognitively demanding.

Interpretation

The findings from this study can help better understand inadequate postural reactions due to cognitive load that may cause stair accidents.     

Using the Actigraph to measure physical activity of people with disabilities: an investigation into measurement issues

This study investigates measurement issues when using the Actigraph motion sensor to measure the physical activity of people with disabilities. Four volunteers with rheumatoid arthritis participated in the study. Activity levels were measured using the Actigraph over four consecutive weekdays. Activity counts were determined using Actigraph Standard Software. The daily percent of waking time spent at each intensity level was calculated and a weighted average calculated to determine a single daily measure of activity. The variability of measurement, over 1, 2, 3 and 4 days, was examined using these weighted and rolling averages. Activity counts were very low, with over 50% of waking time spent in the 'very low' intensity category, demonstrating a marked floor effect. Little variability (+/-0.11 counts/min) in the level of physical activity was found across 1-4 days. The limited variability (consistency across days) in combination with the floor effect indicates that a 1-day data collection period is adequate. The limitations of the Actigraph are thus related to the existing software options, which have been designed for people without rheumatoid arthritis. The Actigraph does not appear to be a sensitive measure in people performing very low physical activity.     

Reliability of computerized surface electromyography for determining the onset of muscle activity

The reliability of a computerized analysis system (CAS) for determining muscle burst onset was compared with the subjective assessments of three trained examiners. A sample of 154 randomly selected, full-wave rectified and filtered electromyographic recordings was evaluated using a test-retest paradigm. Percentages of agreement, Pearson product-moment correlations, analyses of variance (ANOVAs), and intraclass correlation coefficients (ICCs) were used to measure the reliability. The between-rater agreement, which included the computerized EMG assessments, was only 23%. Within-rater agreement and Pearson correlation coefficients were perfect for CAS. The trained examiners' within-rater assessments averaged only 51% agreement, but test-retest correlations were high (r = .78 - r = .82). All ICCs were statistically significant, ranged from .46 to .60, and tended to be higher when the CAS onset determinations were deleted from the analysis. The ANOVAs revealed that trained examiners were more consistent among each other than when their assessments were compared with CAS assessments of EMG recordings. This finding, however, may be facility-specific in that any generalization to other examiners was limited. In contrast to trained examiners, the CAS was free of variations in judgment, ensured perfect reproducibility of trial assessments, and was highly useful for analyzing multi-channel EMG recordings. Although the CAS ensures perfect reliability, validity determinations require visual inspection of trial data.     

An investigation into activity levels of older people on a rehabilitation ward: an observational study

Objectives To investigate the activity levels of older people who were inpatients in a rehabilitation ward.Design Twelve-hour sessions of continuous observation of each subject, over three consecutive weekdays, established activity levels in various categories.Setting Designated older people rehabilitation ward in a Medicine for the Elderly Unit.Participants Convenience sample of six subjects.Main outcome measures Time spent in various, pre-determined activity categories was monitored.Results Activity levels in the ward were low, with subjects spending 19% of the observed time sleeping and a further 46% inactive. Less than 1% of the day involved self-directed physical activity. Basic care took up 16% of the day but intervention by members of the rehabilitation team constituted less than 2% of the subjects’ day.Conclusion Due to methodological limitations, the results of this study cannot be generalized to the whole population of older people in rehabilitation units. However, it has created a baseline from which changes could be made to improve rehabilitation services in this unit, and highlighted issues that are likely to be common in other rehabilitation settings. Moreover, a starting point for further investigation into reasons for lack of activity and how to increase activity to an effective and beneficial level has been established.     

Effects of progressive muscle relaxation on cerebral activity: An fMRI investigation

ObjectivesProgressive muscle relaxation (PMR) is one of the self-management relaxation techniques that can be used in the general population and patients with specific issues. However, no study to date has revealed the brain activity associated with PMR. Therefore, we assessed the changes in brain activity induced by PMR using functional magnetic resonance imaging (fMRI).Design and settingWe conducted an intervention study with PMR and control sessions. The subjects were twelve healthy adult men who had no prior experience of PMR.InterventionsSubjects performed a control session in which muscles were repeatedly simply tensed and relaxed. Subsequently, a PMR session took place, during which muscle tension was reduced through a systematic procedure of tensing and relaxing of muscle groups combined with structured breathing.Main outcome measuresWe identified and visualised brain activity based on individual and group-level analysis of fMRI data.ResultsEleven subjects’ data were analysed. In the control session, brain activity broadly changed, while the change was limited to specific parts of the cerebral cortex and limbic system in the PMR session. PMR gradually decreased activity in the superior frontal gyrus (SFG), inferior frontal gyrus (IFG), and posterior cingulate cortex (PCC). In a region of interest (ROI) analysis, interactions between sessions were observed in the putamen, anterior cingulate cortex (ACC), postcentral gyrus (PCG), and insula.ConclusionsThat PMR led to few areas showing changed activity suggests that the technique may suppress brain activity. Even novices may be able to induce such a focused mental state.     

Transplantation of embryonic motor neurons into peripheral nerve combined with functional electrical stimulation restores functional muscle activity in the rat sciatic nerve transection model

Reinnervation of denervated muscle by motor neurons transplanted into the peripheral nerve may provide the potential to excite muscles artificially with functional electrical stimulation (FES). Here we investigated whether transplantation of embryonic motor neurons into peripheral nerve combined with FES restored functional muscle activity in adult Fischer 344 rats after transection of the sciatic nerve. One week after sciatic nerve transection, cell culture medium containing (cell transplantation group, n = 6) or lacking (surgical control group, n = 6) dissociated embryonic spinal neurons was injected into the distal stump of the tibial and peroneal nerves. Electrophysiological and tissue analyses were performed in the cell transplantation and surgical control groups 12 weeks after transplantation, as well as a in naïve control group (n = 6) that received no surgery. In the cell transplantation group, ankle angle was measured during gait, with and without FES of the peroneal nerve. Ankle angle at mid‐swing was more flexed during gait with FES (26.6 ± 8.7°) than gait without FES (51.4 ± 12.8°, p = 0.011), indicating that transplantated motor neurons in conjunction with FES restored ankle flexion in gait, even though no neural connection between central nervous system and muscle was present. These results indicate that transplantation of embryonic motor neurons into peripheral nerve combined with FES can provide a novel treatment strategy for paralysed muscles. Copyright © 2013 John Wiley & Sons, Ltd.     

Olfaction and muscle activity: an EMG pilot study.

The therapeutic significance of limbic system structures in general, and olfactory structures specifically, has been described by Fox, Ayres, Moore, and Farber in their professional presentations and publications. No data have yet been provided to substantiate claims of the effects of olfactory stimulation on muscle activity. Effects of olfactory stimulation on human muscle activity at rest were studied in seven normal children and seven normal adults. Upper trapezius, biceps brachii, rectus abdominis, and rectus femoris were monitored electromyographically for changes in muscle action potentials using peppermint oil and smelling salts in each of three positions--supine, seated quietly, and standing. Trapezius showed the greatest responsiveness in relation to other muscles. Using peppermint oil, only 18 out of 168 or 10.7 percent of the EMG recordings showed changes in muscle activity. Using smelling salts, only 21 out of 168 or 12.5 percent of the EMG recordings showed changes in muscle activity. Directional effects of peppermint oil could not be predicted, whereas stimulation with smelling salts, when effective, generally produced increased muscle activity. Children were more responsive to olfactory agents than were adults. Sex of subjects did not seem to effect the distribution of responses. When smelling salts was presented as an initial stimulus, subjects showed a greater responsiveness to all stimuli. The present data indicate that proposed effects of olfactory stimulation are more limited than was previously believed. Possible implications for clinical practice and suggestions for further study are presented.     

Direct anterior approach for total hip arthroplasty: Hip biomechanics and muscle activation during three walking tasks

BackgroundTotal hip replacement with minimally invasive direct anterior approach using the “Smith Petersen” interval is an alternative technique to conventional surgery aimed at preserving the integrity of the muscles around the hip joint. This study aimed to observe hip biomechanics, gait variables, hip muscle activation and locomotor performance during three locomotor tasks (forward, lateral, and backward walking), in subjects who undergo total hip arthroplasty with direct anterior approach.MethodsFourteen patients with primary osteoarthritis who underwent direct anterior approach were included in the study. The optoelectronic 3-D motion analysis system integrated with an electromyography surface device was used to acquire the biomechanics of patients before surgery and at 3 and 6 months post-surgery. Spatio-temporal, dynamic, and hip muscle electromyographic parameters were analyzed and compared whit those of healthy controls.FindingsAlmost all gait parameters improved after surgery. The majority of gait variables neared to the control group at 6 months, while the hip joint range of motion did not. The abnormally increased activation of the muscles around the hip joint was reduced at 6 months post-surgery during all three locomotor tasks. Conversely, the altered gait phase-related electromyographic pattern did not change after the surgery.InterpretationOur results indicate that hip and gait function during several locomotor tasks improved after surgery, while simultaneously either preserve or restore the muscle activation around the hip joint. A full biomechanical evaluation of the hip function during locomotion may aid physicians and surgeons in optimizing the management of patients before and after hip replacement surgery.     

The influence of weakness in the vastus medialis oblique muscle on the patellofemoral joint: an in vitro biomechanical study

OBJECTIVE: Investigation of the influence of weakness in the vastus medialis oblique muscle on patellar tracking. DESIGN: In vitro biomechanical study. BACKGROUND: Currently, the influence of weakness in the vastus medialis oblique muscle on patellar tracking has not been well understood. METHODS: Seven human cadaveric knees were used. The direction of loading forces in the rectus femoris/vastus intermedius, vastus medialis oblique, and the vastus lateralis muscles was decided by the muscle alignment of each cadaver knee measured at the time of dissection. The loads used were 60 N in the rectus femoris, 50 N in the vastus lateralis, and 40 N in the vastus medialis oblique, according to the ratio calculated from the cross-sectional study. The weakness of vastus medialis oblique was simulated at 30 N (75%), 20 N (50%), 10 N (25%), and 0 N (0%), and the patellar position was measured for each condition using a magnetic 3 Space Tracker System. The influence of weakness in the vastus medialis oblique muscle on patellar position was investigated with seven cadaver knees using a magnetic 3 Space Tracker System. RESULTS: At 0 degrees and 15 degrees of knee flexion, 75%, 50%, 25% and 0% of the normal vastus medialis oblique muscle led to a significant difference in lateral patellar shift compared to the normal (P<0.05). CONCLUSIONS: Weakness of the vastus medialis caused the patellar lateral shift at 0 degrees and 15 degrees of knee flexion. RELEVANCE: Weakness of the vastus medialis is thought to be an important factor causing patellar subluxation and dislocation. Understanding the relationship between the vastus medialis weakness and patellar tracking will be useful in diagnosis, treatment and prevention of patellar subluxation and dislocation.