Frontal and transverse plane hip kinematics and gluteus maximus recruitment correlate with frontal plane knee kinematics during single-leg squat tests in women

Background

Hip muscle dysfunction may be associated with knee valgus that contributes to problems like patellofemoral pain syndrome. The purpose of this study was to (1) compare knee and hip kinematics and hip muscle strength and recruitment between “good” and “poor” performers on a single-leg squat test developed to assess hip muscle dysfunction and (2) examine relationships between hip muscle strength, recruitment and frontal plane knee kinematics to see which variables correlated with knee valgus during the test.

Methods

Forty-one active women classified via visual rating as “good” or “poor” performers on the test participated. Participants completed 5-repetition single-leg squat tests. Isometric hip extension and abduction strength, gluteus maximus and gluteus medius recruitment, and 3-dimensional hip and knee kinematics during the test were compared between groups and examined for their association with frontal plane knee motion.

Findings

“Poor” performers completed the test with more hip adduction (mean difference = 7.6°) and flexion (mean difference = 6.3°) than “good” performers. No differences in knee kinematics, hip strength or hip muscle recruitment occurred. However, the secondary findings indicated that increased medial hip rotation (partial r = 0.94) and adduction (partial r = 0.42) and decreased gluteus maximus recruitment (partial r = 0.35) correlated with increased knee valgus.

Interpretation

Whereas hip muscle function and knee kinematics did not differ between groups as we'd hypothesized, frontal plane knee motion correlated with transverse and frontal plane hip motions and with gluteus maximus recruitment. Gluteus maximus recruitment may modulate frontal plane knee kinematics during single-leg squats.     

Male and female gluteal muscle activity and lower extremity kinematics during running

Background

Patellofemoral pain is one of the most common lower extremity overuse injuries in runners and is significantly more common in females. This study evaluated differences in the timing and magnitude of gluteal muscle activity as well as hip and knee joint frontal and transverse plane kinematics between male and female runners in the context of this gender bias.

Methods

Twenty healthy male and 20 healthy female runners were participants. Three-dimensional lower extremity kinematics, and gluteus medius and gluteus maximus muscle activation were recorded using motion analysis and electromyography as subjects ran at 3.7 m/s (+/−5%). Comparisons of hip and knee joint kinematic and gluteus muscle activation data were made using independent t-tests (α = 0.05).

Findings

Females ran with 40% greater peak gluteus maximus activation level (P = 0.028, effect size = 0.79) and 53% greater average activation level (P = 0.013, effect size = 0.93) than males. Female runners also displayed greater hip adduction (P = .001, effect size = 1.20) and knee abduction (P = 0.011, effect size = 0.87) angles at initial contact, greater hip adduction at peak vertical ground reaction force (P < 0.001, effect size = 1.31), and less knee internal rotation excursion than males (P = 0.035, effect size = 0.71).

Interpretation

Greater gluteus maximus activation levels during running may predispose females to earlier gluteus maximus fatigue, promoting altered lower extremity running kinematics thought to be associated with the etiology of patellofemoral pain. Gender differences in transverse and frontal plane hip and knee kinematics observed in this study may also contribute to the gender bias for patellofemoral pain among females.     

Gluteal muscle activation during running in females with and without patellofemoral pain syndrome

Background

Hip and knee joint motion in the transverse and frontal plane during running may increase patellofemoral joint stress and contribute to the etiology of patellofemoral joint pain. We evaluated the association between these kinematics and the magnitude and timing of gluteus medius and maximus activity during running in females with patellofemoral pain. We also compared the magnitude and timing of gluteal muscle activity during running between females with and without patellofemoral pain.

Methods

Twenty females with patellofemoral pain and twenty females without knee pain participated in this study. Three-dimensional running kinematics, gluteus medius and gluteus maximus onset time, activation duration, mean activation level, and peak activation level were recorded simultaneously. Gluteal muscle timing and activation level were compared between groups using independent t-tests. The association of gluteal muscle activation parameters running kinematics in females with patellofemoral pain was quantified using Pearson correlation coefficients.

Findings

Females with patellofemoral pain demonstrated delayed (P = 0.028, effect size = 0.76) and shorter (P = 0.01, effect size = 0.88) gluteus medius activation than females without knee pain during running. The magnitude and timing of gluteus maximus activation was not different between groups. Greater hip adduction and internal rotation excursion was correlated with later gluteus medius and gluteus maximus onset, respectively.

Interpretation

Neuromuscular control differences of the gluteal muscles appear to exist among females with patellofemoral pain during running. Interventions to facilitate earlier activation of these muscles may be warranted among females with patellofemoral pain who demonstrate altered running kinematics.     

An evaluation of instruments for scoring physiological and behavioral cues of pain,non-pain related distress,and adequacy of analgesia and sedation in pediatric mechanically ventilated patients: A systematic review

Objectives

Advancing technology allows for successful treatment of children with life-threatening illnesses. Effectively assessing and optimally treating a child's distress during their stay in the Pediatric Intensive Care Unit (PICU) is paramount. Objective measures of distress in mechanically ventilated pediatric patients are increasingly available but few have been evaluated. The objectives of this systematic review were to identify available instruments appropriate for measuring physiological and behavioral cues of pain, non-pain related distress, and adequacy of analgesia and sedation in mechanically ventilated pediatric patients, and evaluate these instruments in terms of their psychometric properties.

Design

A systematic review of original and validation reports of objective instruments to measure pain and non-pain related distress, and adequacy of analgesia and sedation in mechanically ventilated PICU patients was undertaken.

Data sources

A comprehensive search was conducted in 10 databases from January 1970 to June 2011. Reference lists of relevant articles were reviewed to identify additional articles.

Review methods

Studies were included in the review if they met pre-established eligibility criteria. Two independent reviewers reviewed studies for inclusion, assessed quality, and extracted data.

Results

Twenty-five articles were included, identifying 15 instruments. The instruments had different foci including: assessing pain, non-pain related distress, and sedation (n = 2); assessing pain exclusively (n = 4); assessing sedation exclusively (n = 7), assessing sedation in mechanically ventilated muscle relaxed PICU patients (n = 1); and assessing delirium in mechanically ventilated PICU patients (n = 1). The Comfort Scale demonstrated the greatest clinical utility in the assessment of pain, non-pain related distress, and sedation in mechanically ventilated pediatric patients. Modified FLACC and the MAPS are more appropriate, however, for the assessment of procedural pain and other brief painful events. More work is required on instruments for the assessment of distress in mechanically ventilated muscle relaxed PICU patients, and the assessment of delirium in PICU patients.

Conclusions

This review provides essential information to guide PICU clinicians in choosing instruments to assess pain, non-pain related distress, and adequacy of analgesia and sedation in mechanically ventilated pediatric patients. Effective knowledge translation is essential in the implementation, adoption, and successful use of these instruments.     

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.     

Electromyography activity of selected trunk muscles during cardiopulmonary resuscitation

Background

Understanding trunk muscle activity during chest compression may improve cardiopulmonary resuscitation (CPR) training strategies of CPR or prevent low back pain. This study investigates the trunk muscle activity pattern of chest compression in health care providers to determine the pattern alternation during chest compression.

Methods

Thirty-one experienced health care providers performed CPR for 5 minutes at a frequency of 100 compressions per minute. An electromyography (EMG) system was used to record muscle activity in the first minute, the third minute, and the fifth minute. Electrodes were placed bilaterally over the pectoralis major, latissimus dorsi, rectus abdominis, erector spinae, and gluteus maximus. We calculated the root mean square (RMS) value and maximal amplitude of the EMG activity, median frequency, and delivered force.

Results

The maximal amplitude of EMG of the pectoralis major, erector spinae, and rectus abdominis showed large muscle activity above 45% of maximal voluntary contraction under chest compression. There were no significant differences in the RMS value of one chest compression cycle (RMS_100%) and median frequency for all muscles at the first, third, and fifth minutes. Only gluteus maximus showed significant imbalance. The EMG ratios (erector spinae/rectus abdominis; erector spinae/gluteus maximus) increased significantly over time. The delivered force, compression depth, and number of correct depth decreased significantly over time.

Conclusion

We suggest that the muscle power training for the pectoralis major, erector spinae, and rectus abdominis could be helpful for health care providers. Keeping muscle activity balance of bilateral gluteus maximus and maintaining the same level of EMG ratios might be the keys to prevent low back pain while performing CPR.     

Effects of hip extensor fatigue on lower extremity kinematics during a jump-landing task in women: A controlled laboratory study

Background

Lower extremity kinematics may change as a result of impaired hip muscle function, thereby placing athletes at increased risk of injury. The purpose of this study was to examine whether experimentally-induced hip extensor fatigue alters lower extremity kinematics during a jump-landing task in women.

Methods

Forty healthy women were randomly assigned to an experimental group in which participants performed modified Biering-Sørenson tests to fatigue the hip extensors or to a sham control group in which participants performed repeated push-ups to exhaustion. Three-dimensional hip and knee kinematics and gluteus maximus electromyography (EMG) signals were measured during jump-landing tests to examine the effects of hip extensor fatigue.

Findings

Hip extension strength decreased in the experimental group by 25% following the intervention, thereby confirming effects of the fatigue intervention. No group × time interactions in hip and knee motions were statistically significant, indicating that hip and knee kinematics did not change following the fatigue-inducing intervention. Gluteus maximus recruitment during the post-fatigue test, however, increased by 55% in the experimental group.

Interpretation

A 25% reduction in hip extensor strength did not lead to changes in hip or knee kinematics. Rather, participants accommodated for the loss of strength by recruiting more Gmax activation to complete the task. Gmax recruitment may compensate when hip extensor strength is impaired, suggesting that improved neuromuscular control can influence motor performance when strength is diminished.     

Determining the Activation of Gluteus Medius and the Validity of the Single Leg Stance Test in Chronic,Nonspecific Low Back Pain

Objectives

To determine the activation of the gluteus medius in persons with chronic, nonspecific low back pain compared with that in control subjects, and to determine the association of the clinical rating of the single leg stance (SLS) with chronic low back pain (CLBP) and gluteus medius weakness.

Design

Cohort-control comparison.

Setting

Academic research laboratory.

Participants

Convenience sample of people (n=21) with CLBP (>12wk) recruited by local physiotherapists, and age- and sex-matched controls (n=22). Subjects who received specific pain diagnoses were excluded.

Interventions

Not applicable.

Main Outcome Measures

Back pain using the visual analog scale (mm); back-related disability using the Oswestry Back Disability Index (%); strength of gluteus medius measured using a hand dynamometer (N/kg); SLS test; gluteus medius onset and activation using electromyography during unipedal stance on a forceplate.

Results

Individuals in the CLBP group exhibited significant weakness in the gluteus medius compared with controls (right, P=.04; left, P=.002). They also had more pain (CLBP: mean, 20.50mm; 95% confidence interval [CI], 13.11–27.9mm; control subjects: mean, 1.77mm; 95% CI, −.21 to 3.75mm) and back-related disability (CLBP: mean, 18.52%; 95% CI, 14.46%–22.59%; control subjects: mean, .68%; 95% CI, −.41% to 1.77%), and reported being less physically active. Weakness was accompanied by increased gluteus medius activation during unipedal stance (R=.50, P=.001) but by no difference in muscle onset times. Although greater gluteus medius weakness was associated with greater pain and disability, there was no difference in muscle strength between those scoring positive and negative on the SLS test (right: F=.002, P=.96; left: F=.1.75, P=.19).

Conclusions

Individuals with CLBP had weaker gluteus medius muscles than control subjects without back pain. Even though there was no significant difference in onset time of the gluteus medius when moving to unipedal stance between the groups, the CLBP group had greater gluteus medius activation. A key finding was that a positive SLS test did not distinguish the CLBP group from the control group, nor was it a sign of gluteus medius weakness.     

Arthrogenic neuromusculature inhibition: A foundational investigation of existence in the hip joint

Background

Patients and athletes with diminished gluteal muscle activation are thought to have ‘gluteal inhibition’. This may be a component of arthrogenic neuromuscular inhibition, which has been well documented in the knee and generalized to all joints. While clinical evidence surrounding gluteal inhibition increases, supportive research is non-existent. This study investigated whether arthrogenic neuromuscular inhibition occurred about the hip following instillation of intra-articular fluid during functional hip extension tasks.

Methods

Data was collected in a biomechanics laboratory (control) and hospital setting (intervention). Nine healthy individuals (4M/5F) comprised the control group. The intervention group contained twelve patients (4M/8F) with hip pathology requiring a magnetic resonance arthrogram (capsular distension via intra-articular fluid injection) procedure. The participants performed a pelvic bridge (PB) and active hip extension (EXT) before and after the control time or injection. Peak EMG from the gluteus maximus (GM) was collected bilaterally.

Findings

The findings of this study provide substantial support for arthrogenic inhibition following hip intra-articular fluid instillation during functional tasks. Two-way repeated measures ANOVA revealed a significant group by session interaction effect (PB,EXT: affected/unaffected = 0.0192/0.9654 P = 0.05, < 0.0001/0.0826 P = 0.05). Tukey post hoc revealed decreases in ipsilateral peak GM EMG following intervention were significant (0.0238/< 0.0001 P = 0.025). No changes were observed in the control group.

Interpretation

These concepts are of clinical importance to both patient and athletic populations. Understanding the role of gluteal inhibition in the injury process is essential to the development of rehabilitation and prevention protocols. Restoration and promotion of optimal recruitment patterns are crucial to enhancing athletic performance.     

Do Fitflops™ increase lower limb muscle activity?

Background

Fitness toning shoes are becoming increasingly popular, they aim to increase muscle activity, raise energy expenditure and improve overall health while wearing them. Yet there is a lack of consensus in the literature regarding their effectiveness. One such shoe on the market is the Fitflop™ designed to activate leg muscles through density shifts in the shoe's sole. The purpose of this study was to investigate the effect of wearing Fitflops^TM on the muscle activity of the lower limb.

Methods

Twenty three females (age 20.8 (1.3)years, mass 62.9 (11.9)kg, height 165.4 (5.6)cm) participated in the study. Muscle activity of the medial gastrocnemius, biceps femoris, rectus femoris and gluteus maximus of the participants' right limb were recorded using surface electromyography during participation in three different tasks to simulate daily living activities. These were a) treadmill walking b) stair climbing and c) zigzag walking around cones. The participants completed the tasks barefoot, while wearing Fitflops™ and while wearing regular flip flops so that comparisons between muscle activity in the different shoe conditions could be made.

Findings

The results show that there was no significant difference in the activity of the medial gastrocnemius, biceps femoris, rectus femoris and gluteus maximus muscles across all shoe conditions and simulated daily activities (P > 0.05).

Interpretation

Based on these results, the use of Fitflops™ is not recommended as a means of increasing muscle activity of the medial gastrocnemius, biceps femoris, rectus femoris and gluteus maximus during activities of daily living in a healthy recreationally active female population.