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EMG Activation Levels of the 3 Gluteus Medius Subdivisions During Manual Strength Testing.
Abstract
Study Design: Cross-sectional. Context: Gluteus medius (GM) muscle dysfunction is associated with overuse injury. The GM is functionally composed of 3 separate subdivisions: anterior, middle, and posterior. Clinical assessment of the GM subdivisions is relevant to detect strength and activation deficits and guide specific rehabilitation programs. However, the optimal positions for assessing the strength and activation of these subdivisions are unknown. Objective: The first aim was to establish which strength-testing positions produce the highest surface electromyography (sEMG) activation levels of the individual GM subdivisions. The second aim was to evaluate differences in sEMG activation levels between the tested and contralateral (stabilizing) leg. Method: Twenty healthy physically active male subjects participated in this study. Muscle activity usingsEMG was recorded for the GM subdivisions in 8 different strength-testing positions and analyzed using
repeated-measures analysis of variance. Results: Significant differences between testing positions for all 3 GM subdivisions were found. There were significant differences between the tested and the contralateral anterior and middle GM subdivisions (P < .01). The posterior GM subdivision showed no significant difference (P = .154). Conclusion: Side-lying in neutral and side-lying with hip internal rotation are the 2 positions recommended to evaluate GM function and guide specific GM rehabilitation.
... Strength of the gluteus medius muscle was defined as the amount of force output measured by a handheld dynamometer (HHD) during a maximal volitional isometric contraction (MVIC) break test. [35][36][37] Force output was measured in kilograms (kg) using a microFET2 HHD (Hoggan Scientific, LLC, Salt Lake City, UT) on both the control and intervention sides. The HHD is commonly used to assess force production and has been shown to be a reliable and valid measurement tool for assessing strength of the lower extremity musculature. ...
... Raw sEMG data were collected using a two-channel sEMG recording system (MP36R, Biopac, Goleta, CA) and were measured in millivolts (mV). Parameters for recording the raw sEMG data included a rejection ratio of > 110 dB at 60 Hz, a gain of 1000 Hz, band pass filtered at 20-450 Hz, and a sampling rate of 2000 Hz. 37,41,42 Recorded sEMG amplitude readings can be used as a direct measure of the activation level of a muscle during a contraction [43][44][45] and is a common method of assessing the activation level of the gluteus medius muscle during a MVIC as well as dynamic movements. 37,41,42,[46][47][48] Prior to the start of data collection, intrarater and testretest reliability was established for the PI's HHD and sEMG measurements during MVIC break testing of the gluteus medius. ...
... Parameters for recording the raw sEMG data included a rejection ratio of > 110 dB at 60 Hz, a gain of 1000 Hz, band pass filtered at 20-450 Hz, and a sampling rate of 2000 Hz. 37,41,42 Recorded sEMG amplitude readings can be used as a direct measure of the activation level of a muscle during a contraction [43][44][45] and is a common method of assessing the activation level of the gluteus medius muscle during a MVIC as well as dynamic movements. 37,41,42,[46][47][48] Prior to the start of data collection, intrarater and testretest reliability was established for the PI's HHD and sEMG measurements during MVIC break testing of the gluteus medius. Ten participants with characteristics consistent with the study's sample were recruited. ...
Background
Latent trigger points have been identified as a source of impaired muscle function giving rise to a reduction in force production and alterations in muscle activation patterns and movement efficiency. There is limited investigation into the effectiveness of a treatment in reducing these clinical manifestations.
Purpose
To investigate whether the application of trigger point dry needling (TDN) to latent trigger points within the gluteus medius musculature affected strength measurements and muscle activation levels immediately following intervention.
Design
Quasi experimental, single group, pretest-posttest, randomized control study
Methods
A control and an intervention side were randomly assigned for each participant ( N = 39). Hand held dynamometer (HHD) force measurements and raw surface electromyography (sEMG) amplitude readings were recorded during maximal volitional isometric contractions of the gluteus medius in two separate positions before and after application of TDN. Comparison of within and between group data were conducted.
Results
A statistically significant interaction between time (pre-TDN to post-TDN) and groups (intervention side and control side), p < 0.001 was found for HHD measurements in both positions. Post hoc analysis revealed a statistically significant difference ( p < 0.001) for all comparisons in the side lying neutral (SL0) position, while statistically significant differences ( p < 0.001) were found for pre and post-TDN measurements within intervention side as well as between the intervention and control side for post-TDN measurements in the side lying internal rotation (SLIR) position. For sEMG amplitude measurements, statistically significant differences were found only in the SL0 position for within group comparisons on the intervention side ( p = 0.009) and for between group comparisons for post-TDN measurements ( p = 0.002).
Conclusion
Application of TDN to latent trigger points within the gluteus medius can significantly increase gluteus muscle force production immediately following intervention while reducing the level of muscle activation required during contraction.
Level of Evidence
Level 2
... As a single muscle, the gluteus medius (GM) acts as primary hip abductor [1,2] and has an important role in pelvic stabilization and lower limb motion con-trol [3][4][5]. It is a key muscle in stabilizing the hip during single-limb stance to prevent the contralateral pelvis dropping and is critical to controlling hip adduction and internal rotation during weight-bearing activities [4,6,7]. ...
... To our knowledge, this was the first study to eval-uate the activation of the GM subdivision during FFP exercise, and comparison with other studies could not be made. Current research is mainly focused on weight-bearing exercises [4,7,28], hip isometric contractions [2,41] and manual strength testing [3], whereas a limited information exist on the muscular activity of the GM subdivisions during non-weight-bearing exercises. Nevertheless, Semciw [42] and Moore [43] examined the ability of the clam exercise on the activation of GM individual subdivisions and interestingly found greater activation levels of posterior subdivision relative to the middle and anterior subdivisions. ...
Background:
Gluteus medius (GM) is a segmented muscle involving three muscular subdivisions. Rehabilitation exercises has been suggested to strengthen specific subdivisions.
Objective:
This study aimed to evaluate muscular activation of the anterior, middle, and posterior subdivisions of the GM during two different exercises.
Methods:
A total of 28 healthy active subjects participated in this study. Muscle activity using surface electromyography was recorded for the three GM subdivisions during figure-of-four position (FFP) and wall press (WP). Non-parametric Kruskal-Wallis test was used to detect differences between GM subdivisions on each exercise and the Mann-Whitney U test was used to compare muscular activation across exercises.
Results:
There were statistically significant differences (P< 0.001) in all GM subdivision during FFP and WP exercises. Both exercises showed greater activation of the posterior subdivision than the middle and anterior subdivisions, with the WP causing highest activation of the posterior subdivision.
Conclusion:
In line with the WP exercise, the FFP produces sufficient activity to provide potential strength gains on the posterior subdivision and could be a viable option to include in the early stages of the rehabilitation process. Clinicians may use this information to make more informed decisions about exercise selection for strengthening specific GM subdivision.
... The neuromuscular activity was recorded by surface electromyography (EMG) from the anterior, middle, and posterior portions of the GM. With the participant standing, the surface electrodes for the anterior region were placed at 50% of the distance between the anterosuperior iliac spine and the greater trochanter for the anterior fiber of the GM, the electrodes for the middle fibers were placed at 50% of the distance between the greater trochanter and the iliac crest, and the electrodes for the posterior fibers were placed at 33% of the distance between the posterior ilium and the greater trochanter (Otten et al., 2015). Electrodes were placed after the skin was FIGURE 2 | Crutch locomotion patterns. ...
... shaved and cleaned according to the "Surface Electromyography for the Non-Invasive Assessment of Muscles" guidelines (Hermens et al., 2000). After the placement of each electrode, the participant was requested to perform a maximal isometric test to check the selective action of the GM according to the sensor placement (Semciw et al., 2014;Otten et al., 2015). The quality of the signal was checked visually before any recording. ...
Crutches can help with the locomotion of people with walking disorders or functional limitations. However, little is known about hip muscle activation during stair ascending using different crutch locomotion patterns in people without disorders and limitations. Thus, we determined the acute effects of elbow crutch locomotion on gluteus medius (GM) activity during stair ascending. This comparative analytic cross-sectional study enrolled ten healthy men (22.0 ± 0.47 years). Participants climbed up the stairs with elbow crutches using one or two crutches, with ipsilateral or contralateral use, and after loading or unloading a limb. EMG signals were recorded from anterior, middle, and posterior portions of the GM and compared between the crutch conditions. The Kruskal–Wallis test and Dunn’s multiple comparison test were performed (α = 5%). The activation of the GM increased with the ipsilateral use of crutches, with two crutches and three points, and when all the load depended only on one limb. GM activation decreased with contralateral use and in the unload limb. In conclusion, ascending stairs with elbow crutches alters the GM activation. The more critical factors were choosing the crutches’ lateral use, the number of crutches, and if the limb is loaded or unloaded while ascending the stairs. Our findings can be helpful to increase or decrease the GM activation for those who use or will use crutches.
Patients with knee osteoarthritis (KOA) often have impaired muscle function of the weight-bearing muscles, particularly in the knee and hip joints. This can lead to a significant loss of strength and power and may play a role in the perceived instability of the knee joint. The purpose of this study was to compare the maximum isometric strength of the hip abductor and knee extensor muscles between patients with KOA with and without perceived instability.
Nineteen patients with KOA participated in this cross-sectional study and were divided into two groups. The first group (n = 10; women = 4, men = 6, mean age = 67.4 ± standard deviation [SD] 6.4 years) consisted of patients with self-reported instability in the knee joint, and the second group (n = 9; women = 5, men = 4, mean age = 69.6 ± SD 6.7 years) consisted of patients without self-reported instability. Functional and activity limitations were quantified using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Maximum isometric strength of the hip abductors and knee extensors was measured using a belt-mounted handheld dynamometer and expressed as torque (Newton meters [Nm]) by multiplication with the determined lever arm. Torque was normalized to body weight and height.
Patients with instability (median WOMAC score = 68) achieved a significantly lower mean torque in hip abduction than the patients without instability (median WOMAC score = 39) (p = 0.01; Cohen’s d = 1.31). There was no significant difference in knee extension torque between the groups (p = 0.202; Cohen’s d = 0.58).
KOA patients with instability were able to develop significantly lower hip abductor strength than those without instability, suggesting that targeted strength training of this muscle group may be important for this group of patients.
Introduction:
The gluteus medius (GMED) and gluteus maximus (GMAX) play a crucial role in postural control, and postural control is impaired in individuals with chronic ankle instability (CAI). However, the association between CAI and the recruitment of these muscles remains unclear. The purpose of this study was to explore the contractile thickness of GMED and GMAX during functional movements in individuals with CAI compared to healthy controls.
Evidence acquisition:
A systematic search was conducted in six databases (PubMed, Embase, Cochrane Library, Web of Science, EBSCO, and PEDro). Included studies involved the contractile thickness of GMED and/or GMAX comparing CAI with non-CAI. The extracted data were subjected to meta-analysis for observing the differences between the two. The correlation and difference in contraction between GMED and GMAX were analyzed using the Pearson Correlation Coefficient (PCC) and t-test, respectively.
Evidence synthesis:
Six studies with 176 participants were found. Contractile thickness measured by ultrasound showed GMED thickness change to be lower in CAI than in controls during functional movements and exercise (WMD: -0.08; 95% CI: -0.11, -0.04; P<0.00001). There was no significant difference between the two groups with respect to contraction of GMAX (WMD: 0.02; 95% CI: -0.01, 0.05; P=0.25). The PCC and P value (t-test) between the ratio of contractile thickness of GMED and GMAX in CAI were 0.397 and 0.029 respectively, indicating activity differences.
Conclusions:
CAI may be associated with weaker GMED recruitment during functional movements and exercise, but the activation of GMAX in CAI may be unaffected.
The aim of this study was to compare the effect of gluteus medius strengthening exercises versus sacroiliac joint mobilization in anterior sacroiliac joint dysfunction. Comparative study. Thirty adult patients with pain, tenderness on posterior superior iliac spine and chronic low back pain from both genders participated in this study, their age was ranging from 25 to 40 years old, their body mass index was ranging from 20 to 25 (kg/m 2). The thirty patients were randomly divided into 2 equal groups with 15 patients each. Both groups were given conventional physiotherapy which included ultrasound and corrective exercises as a baseline treatment. Along with conventional physiotherapy Group A received strengthening exercises for gluteus medius subdivisions while Group B received mobilization techniques. The treatment duration was for 3 weeks. Provocation tests, pelvic tilt angle and pain were measured for evaluation before starting the treatment and then after 3 weeks. There was no significant difference in pain and pelvic tilt between both groups post-treatment (p > 0.05). There was a significant decrease in pain and pelvic tilt angle post treatment in group A and B compared with that pre-treatment (p > 0.001). There was no significant difference in the results of provocation tests between group A and B at pre and post treatment (p > 0.05). There was a significant decrease in the number of patients who had positive provocation tests post-treatment compared with that pre-treatment (p < 0.05) in both groups. Both the gluteus medius strengthening exercises and the sacroiliac joint mobilization techniques were effective in treatment of anterior sacroiliac joint dysfunction.
Introduction: The aim of this study was to investigate the Effect of CST90 fatigue protocol on timing and electromyography activity of gluteus medius muscle of soccer players
Materials and Methods: This is an intragroup study. Timing and electromyography activity of gluteus medius of soccer players (15 subjects, Mean ± SD: Age (yr): 25.4±3.8, Height (cm): 177.3±3.6, Weight (kg): 69.8±4.6) before and after engaging on CST90 were measured. Surface Electromyography (ME 6000، Mega Electronics Ltd.، FIN-70211 KUOPIO), Polar pulse meter, and foot switch devices were used to collect data. Electromyography activity of muscle was record during single leg drop and Megawin, Matlab and SPSS software were used to analyze data. Descriptive and repeated measure of ANOVA were used.
Results: Results of this study show differences in timing of gluteus medius muscle activity in different periods of test but it wasn’t significant (F=2.55, F= 1.89, P>0.05). Significant differences were observed between feed forward and feedback activity during EMG recordings (F=4.84, F= 3.71, P≤0.05). Also there was a significant difference between initial and final EMG recording (P≤0.05).
Conclusion: With regarding to gluteus medius muscle role in pelvis stability, femur movement, controlling the knee valgus, and also effects of fatigue on timing and muscle activity, trainers should add specific programs (i.e: induced -endurance and tolerance) for gluteus muscle and therefor prevent knee instability.
Verbal encouragement (VE) is commonly used to encourage patients to perform to their maximum potential during exercise sessions or for various assessment procedures. This controlled trial investigated the effectiveness of VE during a motor endurance performance. Subjects in the experimental (n = 32) and control group (n = 26) performed two trials of a leg-holding task, one on each leg. The control group were simply timed, while the experimental group performed one trial in the manner of the control group and one where they were verbally encouraged. These subjects thus acted as their own control. Results of a MANOVA showed that the size of effect was different between the two leg-holding trials depending upon the group (F(1,50) = 12.59, p < 0.001). Verbal encouragement significantly increased performance compared to the control group by 39% and by 33.5% compared to the subject's own control trial. Results are discussed in terms of the previous literature and suggestions are made for future investigations.
Objective:
There is growing evidence to support the association of gluteal muscle strength deficits in individuals with patellofemoral pain syndrome (PFPS) and the effectiveness of gluteal strengthening when treating PFPS. In additiona, an impressive body of work evaluating gluteal electromyography (EMG) has recently emerged, further supporting the importance of gluteal muscle function in PFPS. This systematic review synthesises these EMG findings in order to better understand the role of gluteal muscle activity in the aetiology, presentation and management of PFPS.
Methods:
MEDLINE, EMBASE, CINAHL, Web of Knowledge and Google Scholar databases were searched in September 2011 for prospective and case-control studies evaluating the association of gluteal EMG with PFPS. Two independent reviewers assessed each paper for inclusion and quality. Means and SDs were extracted from each included study to allow effect size calculations and comparison of results.
Results:
Ten case-control, but no prospective studies were identified. Moderate-to-strong evidence indicates gluteus medius (GMed) activity is delayed and of shorter duration during stair negotiation in PFPS sufferers. In addition, limited evidence indicates GMed activity is delayed and of shorter duration during running, and gluteus maximus (GMax) activity is increased during stair descent.
Conclusions:
Delayed and shorter duration of GMed EMG may indicate impaired ability to control frontal and transverse plane hip motion. Further research evaluating the value of gluteal muscle activity screening in identifying individuals most likely to develop PFPS, and the effectiveness of interventions targeting changes to gluteal muscle activation patterns is needed.
Background: Strengthening exercise for gluteus medius (GMed) is an important management strategy for lower limb disorders such as osteoarthritis and patello-femoral syndrome, and exercises in functional positions are commonly prescribed. Electromyography (EMG) can be used to measure muscle activation to ascertain the extent of muscle recruitment during exercise. Objectives: To review the available evidence on the magnitude of GMed activation measured with EMG during therapeutic exercise. Methods: A structured review of studies which measured EMG magnitude of GMed during a range of therapeutic exercises was undertaken. Amplitude levels of GMed were reported as a percentage of maximum voluntary isometric contraction. Results: Fifteen studies were included. Most of these were conducted on asymptomatic volunteers, with three studies investigating individuals with knee or hip pathology. A wide range of exercises was investigated in both weightbearing (WB) and nonweightbearing (NWB) positions. In general, EMG activation was greater in WB positions but variation occurred across studies. Many exercises were below levels considered necessary for strength gains. Generally, methodological quality was good but there was variation in the reporting of technical aspects of the study. Many of the studies did not acknowledge the range of limitations of EMG in measuring muscle activation in therapeutic exercise. Conclusions: The results provide some information regarding GMed recruitment during exercise, although there were some discrepancies in results between studies which may be due to factors related to EMG measurement and recording as well as the execution of the exercise. Extrapolation of results to symptomatic populations in a clinical setting islimited.
Ankle injuries are the most common injury in basketball players. However, no prospective studies have been performed to determine if wearing lace-up ankle braces will reduce the incidence of ankle injuries in high school athletes.
This trial was undertaken to determine if lace-up ankle braces reduce the incidence and severity of acute first-time and recurrent ankle injuries sustained by high school basketball players. Design: Randomized controlled trial; Level of evidence, 1.
A total of 1460 male and female basketball players from 46 high schools were randomly assigned to a braced or control group. The braced group players wore lace-up ankle braces during the 2009-2010 basketball season. Athletic trainers recorded brace compliance, athlete exposures, and injuries. Cox proportional hazards models (adjusted for demographic covariates), accounting for intracluster correlation, were utilized to compare time to first acute ankle injury between groups. Injury severity (days lost) was tested with the Wilcoxon rank-sum test.
The rate of acute ankle injury (per 1000 exposures) was 0.47 in the braced group and 1.41 in the control group (Cox hazard ratio [HR] 0.32; 95% confidence interval [CI] 0.20, 0.52; P < .001). The median severity of acute ankle injuries was similar (P = .23) in the braced (6 days) and control group (7 days). For players with a previous ankle injury, the incidence of acute ankle injury was 0.83 in the braced group and 1.79 in the control group (Cox HR 0.39; 95% CI 0.17, 0.90; P = .028). For players who did not report a previous ankle injury, the incidence of acute ankle injury was 0.40 in the braced group and 1.35 in the control group (Cox HR 0.30; 95% CI 0.17, 0.52, P < .001).
Use of lace-up ankle braces reduced the incidence but not the severity of acute ankle injuries in male and female high school basketball athletes both with and without a previous history of an ankle injury.
Gluteus medius (GM) dysfunction is associated with many musculoskeletal disorders. Rehabilitation exercises aimed at strengthening GM appear to improve lower limb kinematics and reduce pain. However, there is a lack of evidence to identify which exercises best activate GM. In particular, as GM consists of three distinct subdivisions, it is unclear if GM activation is consistent across these subdivisions during exercise. The aim of this study was to determine the activation of the anterior, middle and posterior subdivisions of GM during weight-bearing exercises.
A single session, repeated-measures design. The activity of each GM subdivision was measured in 15 pain-free subjects using surface electromyography (sEMG) during three weight-bearing exercises; wall squat (WS), pelvic drop (PD) and wall press (WP). Muscle activity was expressed relative to maximum voluntary isometric contraction (MVIC). Differences in muscle activation were determined using one-way repeated measures ANOVA with post-hoc Bonferroni analysis.
The activation of each GM subdivision during the exercises was significantly different (interaction effect; p < 0.001). There were also significant main effects for muscle subdivision (p < 0.001) and for exercise (p < 0.001). The exercises were progressively more demanding from WS to PD to WP. The exercises caused significantly greater activation of the middle and posterior subdivisions than the anterior subdivision, with the WP significantly increasing the activation of the posterior subdivision (all p < 0.05).
Posterior GM displayed higher activation across all three exercises than both anterior and middle GM. The WP produced the highest %MVIC activation for all GM subdivisions, and this was most pronounced for posterior GM. Clinicians may use these results to effectively progress strengthening exercises for GM in the rehabilitation of lower extremity injuries.
Closed kinetic chain exercises are an integral part of rehabilitation programs after lower extremity injury. Sex differences in lower extremity kinematics have been reported during landing and cutting; however, less is known about sex differences in movement patterns and activation of the hip musculature during common lower extremity rehabilitation exercises.
To determine whether lower extremity kinematics and muscle activation levels differ between sexes during closed kinetic chain rehabilitation exercises.
Cross-sectional with 1 between-subjects factor (sex) and 1 within-subjects factor (exercise).
Research laboratory.
Participants included 21 women (age = 23 +/- 5.8 years, height = 167.6 +/- 5.1 cm, mass = 63.7 +/- 5.9 kg) and 21 men (age = 23 +/- 4.0 years, height = 181.4 +/- 7.4 cm, mass = 85.6 +/- 16.5 kg). Intervention(s): In 1 testing session, participants performed 3 trials each of single-leg squat, lunge, and step-up-and-over exercises.
We recorded the peak joint angles (degrees) of knee flexion and valgus and hip flexion, extension, adduction, and external rotation for each exercise. We also recorded the electromyographic activity of the gluteus maximus, rectus femoris, adductor longus, and bilateral gluteus medius muscles for the concentric and eccentric phases of each exercise.
Peak knee flexion angles were smaller and peak hip extension angles were larger for women than for men across all tasks. Peak hip flexion angles during the single-leg squat were smaller for women than for men. Mean root-mean-square amplitudes for the gluteus maximus and rectus femoris muscles in both the concentric and eccentric phases of the 3 exercises were greater for women than for men.
Sex differences were observed in sagittal-plane movement patterns during the rehabilitation exercises. Because of the sex differences observed in our study, future researchers need to compare the findings for injured participants by sex to garner a better representation of altered kinematic angles and muscle activation levels due to injury.
High-intensity resistance training plays an essential role in the prevention and rehabilitation of musculoskeletal injuries and disorders. Although resistance exercises with heavy weights yield high levels of muscle activation, the efficacy of more user-friendly forms of exercise needs to be examined.
The aim of this study was to investigate muscle activation and perceived loading during upper-extremity resistance exercises with dumbbells compared with elastic tubing.
A single-group, repeated-measures study design was used.
Exercise evaluation was conducted in a laboratory setting.
Sixteen female workers (aged 26-55 years) without serious musculoskeletal diseases and with a mean neck and shoulder pain intensity of 7.8 on a 100-mm visual analog scale participated in the study.
Electromyographic (EMG) activity was measured in 5 selected muscles during the exercises of lateral raise, wrist extension, and shoulder external rotation during graded loadings with dumbbells (2-7.5 kg) and elastic tubing (Thera-Band, red to silver resistance). The order of exercises and loadings was randomized for each individual. Electromyographic amplitude was normalized to the absolute maximum EMG amplitude obtained during maximal voluntary isometric contraction and exercise testing. Immediately after each set of exercise, the Borg CR10 scale was used to rate perceived loading during the exercise.
Resistance exercise with dumbbells as well as elastic tubing showed increasing EMG amplitude and perceived loading with increasing resistance. At the individually maximal level of resistance for each exercise-defined as the 3 repetitions maximum-normalized EMG activity of the prime muscles was not significantly different between dumbbells (59%-87%) and elastic tubing (64%-86%). Perceived loading was moderately to very strongly related to normalized EMG activity (r=.59-.92). Limitations The results of this study apply only for exercises performed in a controlled manner (ie, without sudden jerks or high acceleration).
Comparably high levels of muscle activation were obtained during resistance exercises with dumbbells and elastic tubing, indicating that therapists can choose either type in clinical practice. The Borg CR10 can be a useful aid in estimating intensity of individual rehabilitation protocols.
Functional exercises are often used in strengthening programs after lower extremity injury. Activation levels of the stabilizing hip muscles have not been documented.
To document the progression of hip-muscle activation levels during 3 lower extremity functional exercises.
Cross-sectional.
Laboratory.
44 healthy individuals, 22 women and 22 men. Intervention: Subjects, in 1 testing session, completed 3 trials each of the lunge (LUN), single-leg squat (SLSQ), and step-up-and-over (SUO) exercise.
Root-mean-square muscle amplitude (% reference voluntary muscle contraction) was measured for 5 muscles during the 3 exercises: rectus femoris (RF), dominant and nondominant gluteus medius (GMed_D and GMed_ND), adductor longus (ADD), and gluteus maximus (GMX).
The RF, GMAX, and GMed_D were activated in a progression from least to greatest during the SUO, LUN, and SLSQ. The progression for the GMed_ND activation was from least to greatest during the SLSQ, SUO, and then LUN. Activation levels of the ADD showed no progression.
Progressive activation levels were documented for muscles acting on the hip joint during 3 functional lower extremity exercises. The authors recommend using this exercise progression when targeting the hip muscles during lower extremity strengthening.
The objective of the present study was to establish test-retest reliability of isokinetic hip torque and prime mover electromyogram (EMG) through the three cardinal planes of motion. Thirteen healthy young adults participated in two experimental sessions, separated by approximately one week. During each session, isokinetic hip torque was evaluated on the Biodex Isokinetic Dynamometer at a velocity of 60 deg/s. Subjects performed three maximal-effort concentric and eccentric contractions, separately, for right and left hip abduction/adduction, flexion/extension, and internal/external rotation. Surface EMGs were sampled from the gluteus maximus, gluteus medius, adductor, medial and lateral hamstring, and rectus femoris muscles during all contractions. Intraclass correlation coefficients (ICC - 2,1) and standard errors of measurement (SEM) were calculated for peak torque for each movement direction and contraction mode, while ICCs were only computed for the EMG data. Motions that demonstrated high torque reliability included concentric hip abduction (right and left), flexion (right and left), extension (right) and internal rotation (right and left), and eccentric hip abduction (left), adduction (left), flexion (right), and extension (right and left) (ICC range=0.81-0.91). Motions with moderate torque reliability included concentric hip adduction (right), extension (left), internal rotation (left), and external rotation (right), and eccentric hip abduction and adduction (right), flexion (left), internal rotation (right and left), and external rotation (right and left) (ICC range=0.49-0.79). The majority of the EMG sampled muscles (n=12 and n=11 for concentric and eccentric contractions, respectively) demonstrated high reliability (ICC=0.81-0.95). Instances of low, or unacceptable, EMG reliability values occurred for the medial hamstring muscle of the left leg (both contraction modes) and the adductor muscle of the right leg during eccentric internal rotation. The major finding revealed high and moderate levels of between-day reliability of isokinetic hip peak torque and prime mover EMG. It is recommended that the day-to-day variability estimates concomitant with acceptable levels of reliability be considered when attempting to objectify intervention effects on hip muscle performance.
The effects of prophylactic ankle braces on lower extremity functional performance in healthy participants have not been studied extensively.
To determine if prophylactic ankle braces affected multidirectional reach distances during a test of dynamic balance.
Crossover.
Laboratory.
Thirty-six healthy, physically active volunteers (18 men, 18 women; age = 23.6 +/- 2.7 years, height = 173.8 +/- 9.3 cm, mass = 74.4 +/- 12.7 kg, reach-leg length = 91.9 +/- 5.1 cm).
Volunteers performed balance testing in 3 conditions: unbraced, while wearing a semirigid ankle brace, and while wearing a lace-up ankle brace.
We used the Star Excursion Balance Test, calculating the mean of 3 attempts in 8 directions (anterior, anterior-medial, medial, posterior-medial, posterior, posterior-lateral, lateral, and anterior-lateral), normalized by the participant's reach-leg length. Data were collected after 6 practice attempts for each of the conditions according to a balanced Latin square.
Bracing condition had no effect (P > .05) on any of the Star Excursion Balance Test directional measures. The largest mean difference due to bracing was 2.5% between the lace-up brace condition and the control in the posterior reach direction. This indicates that the actual reach differences due to bracing were less than 5.08 cm (2 inches) in length.
Clinicians can be confident that the prophylactic use of ankle braces does not disrupt lower extremity dynamic balance during a reaching task in healthy participants.
Ankle braces in sports are used for prevention of ankle sprains. Besides restricting inversion and eversion, it is possible that an ankle brace also reduces the functional range of motion of the ankle joint. Consequently, their use could also impair athletic performance. It is unlikely that prophylactic ankle bracing will gain wide acceptance if bracing hinders athletic performance. The purpose of this paper is to review the literature on the effect of ankle bracing on vertical jump height, running speed, agility and broad jump performance.
In 2 studies, 2 ankle braces negatively affected vertical jump height. Other studies did not find a significant effect on vertical jump performance when wearing an ankle brace. One study found a negative effect on running speed and broad jump performance when wearing a lace-on brace. In other studies, no effects on running speed and broad jump were found. In 1 study, agility was negatively affected when wearing an ankle brace, although agility was not significantly affected in other studies. The effect of prolonged use of an ankle brace is unknown, but could possibly influence ankle musculature and ligament function. Further research is necessary to study the effect of prolonged ankle bracing on performance.
Ascending and descending stairs is a provocative activity for anterior knee pain (AKP) patients. The gluteus medius (GM) acts on the lower extremity in the frontal plane and can affect forces at the knee. Determining activation patterns of the GM in patients with AKP can help identify efficacy of training the GM in this population. This study examined electromyographic (EMG) firing patterns in lower extremity muscles in subjects with AKP while ascending and descending stairs. Subjects in the AKP group ( n=16) demonstrated general AKP for at least 2 months compared to the control group ( n=12); neither group had any history of knee trauma. Subjects were instrumented with EMG electrodes on the vastus medialis oblique (VMO), vastus lateralis (VL), and GM. Retroreflective markers were placed on lower extremities to determine knee flexion angle, and frontal plane pelvis orientation at toe contact. Subjects then performed a series of five stair (height=18 cm) ascent and descent trials. Repeated measures analyses of variance were performed on EMG and kinematic variables, between the two groups and between the symptomatic and asymptomatic sides. In the AKP group the GM demonstrated delayed onset and shorter durations for stair ascent and shorter duration during descent. There were no significant differences between sides in the AKP group. Consistent with previous studies, subjects in the AKP group demonstrated no difference in the VMO onsets relative to VL onsets compared to the control group. Changes in neuromuscular activity patterns may be a result of a compensations strategy due to AKP. Training of GM and other hip muscles is warranted during rehabilitation of AKP patients.
Altogether, 100 uninjured professional rugby league players were evaluated over a 2-year period. Their height, body mass, sum of skinfolds, girths and bone diameters were recorded. A Cybex 340 isokinetic dynamometer was used to determine peak torque, work, power, endurance ratios and peak torque ratios of the hip abductors and adductors (5 repetitions at 0.52 and 2.08 rad. s(- 1); 20 repetitions at 3.66 rad. s(- 1)) and knee flexors and extensors (4 repetitions at 1.04 and 3.14 rad. s(- 1); 30 repetitions at 5.22 rad. s(- 1)). Hip abduction and adduction were also assessed with the hip in external rotation. Discriminant function analysis was conducted on all predictor variables to develop a multivariate predictive model capable of classifying players with a high degree of accuracy into groups with and without a groin injury. The model consisted of eight variables and correctly classified 91.7% of the non-injured players and 90.5% of the injured players. The correct classification for the model as a whole was 91.4%. The aetiological factors identified as being related to injury of the groin musculotendinous unit included abduction and adduction-with-rotation peak torque, angle of adduction and abduction-with-rotation peak torque, strength ratio of hip muscle groups, bilateral difference in extension peak torque, femur diameter and body mass.
Clinicians surmise that the application of external ankle support reduces the ability to perform functional skills and movements, but the outcomes from some of these studies have been inconclusive.
To meta-analyze studies regarding the effects of external ankle support on lower-extremity functional performance measures.
A total of 93 effects from 17 randomized controlled trials utilizing predominantly crossover designs with recreationally active participants and competitive athletes were subjected to a random-effects meta-analysis. The treatment variable was external ankle support with three levels: adhesive tape, lace-up style, and semirigid style. Differences between mean changes in treatment and control groups were computed as standardized effect sizes for sprint, agility, and vertical jump performance with their 90% confidence intervals (CI). Effect sizes >0.20 were considered substantial.
The greatest effect of ankle support on performance was a negative effect of lace-up style brace on sprint speed (effect size -0.22, 90% CI -0.47 to 0.03), equivalent to approximately 1% impairment of speed. The other effects of external ankle support on performance were insubstantial, though most were negative, and their lower confidence limits allowed for realistic chances of impaired performance. Substantial true variation between studies, although poorly defined, was also present for some effects, further increasing the likelihood of performance impairment in some settings.
More research is needed to reduce the uncertainty in the effects of external ankle support on performance. In the meantime, it is our opinion that the benefit in preventing injury outweighs the possibility of substantial but small impairment of performance when athletes use external ankle support.
Iliotibial band syndrome (ITBS) is the most common cause of lateral knee pain in runners. It is an overuse injury that results from repetitive friction of the iliotibial band (ITB) over the lateral femoral epicondyle, with biomechanical studies demonstrating a maximal zone of impingement at approximately 30 degrees of knee flexion. Training factors related to this injury include excessive running in the same direction on a track, greater-than-normal weekly mileage and downhill running. Studies have also demonstrated that weakness or inhibition of the lateral gluteal muscles is a causative factor in this injury. When these muscles do not fire properly throughout the support phase of the running cycle, there is a decreased ability to stabilise the pelvis and eccentrically control femoral abduction. As a result, other muscles must compensate, often leading to excessive soft tissue tightness and myofascial restrictions. Initial treatment should focus on activity modification, therapeutic modalities to decrease local inflammation, nonsteroidal anti-inflammatory medication, and in severe cases, a corticosteroid injection. Stretching exercises can be started once acute inflammation is under control. Identifying and eliminating myofascial restrictions complement the therapy programme and should precede strengthening and muscle re-education. Strengthening exercises should emphasise eccentric muscle contractions, triplanar motions and integrated movement patterns. With this comprehensive treatment approach, most patients will fully recover by 6 weeks. Interestingly, biomechanical studies have shown that faster-paced running is less likely to aggravate ITBS and faster strides are initially recommended over a slower jogging pace. Over time, gradual increases in distance and frequency are permitted. In the rare refractory case, surgery may be required. The most common procedure is releasing or lengthening the posterior aspect of the ITB at the location of peak tension over the lateral femoral condyle.
Single-occasion, repeated-measures design.
To determine the magnitude of hip abductor muscle activation during 6 rehabilitation exercises.
Many researchers have reported that hip strengthening, especially of the hip abductors, is an important component of a lower extremity rehabilitation program. Clinicians employ non-weight-bearing and weight-bearing exercise to strengthen the hip musculature; however, researchers have not examined relative differences in muscle activation during commonly used exercises. Information regarding these differences may provide clinicians with a scientific rationale needed for exercise prescription.
Sixteen healthy subjects (mean +/- SD age, 27 +/- 5 years; range, 18-42 years; mean +/- SD height, 1.7 +/- 0.2 m; mean +/- SD body mass, 76 +/- 15 kg) volunteered for this study. Bipolar surface electrodes were applied to the right gluteus medius muscle. We measured muscle activation as subjects performed 3 non-weight-bearing (sidelying right hip abduction and standing right hip abduction with the hip at 0 degrees and 20 degrees of flexion) and 3 weight-bearing (left-sided pelvic drop and weight-bearing left hip abduction with the hips at 0 degrees and 20 degrees of flexion) exercises. Data were expressed as a percent of maximum voluntary isometric contraction of the right gluteus medius. Differences in muscle activation across exercises were determined using a 1-way analysis of variance with repeated measures, followed by a sequentially rejective Bonferroni post hoc analysis to identify differences between exercises.
The weight-bearing exercises demonstrated significantly greater EMG amplitudes (P<.001) than all non-weight-bearing exercises except non-weight-bearing sidelying hip abduction.
The weight-bearing exercises and non-weight-bearing sidelying hip abduction exercise resulted in greater muscle activation because of the greater external torque applied to the hip abductor musculature. Although the non-weight-bearing standing hip abduction exercises required the least activation, they may benefit patients who cannot safely perform the weight-bearing or sidelying hip abduction exercises. Clinicians may use results from this study when designing hip rehabilitation programs.
The one leg hop for distance is one of the most commonly employed functional tests utilized in the evaluation of the ACL deficient and reconstructed patient. While the reliability of the hop test scores has been well established, validity studies have revealed low sensitivity rates in detecting functional limitations using the hop index (the ratio or percentage of limb performance). However, the impact of the inherent limitations associated with the hop index have not been investigated to date. One specific limitation relates to the impact of the differences in the underlying hop distance scores. Therefore, this pilot study set out to determine: 1) the impact that between limb differences in hop distance has on the sensitivity of the hop index in detecting functional limitations and; 2) whether a logarithmic transformation of the underlying hop distance scores improves the sensitivity of the hop index.
A cross sectional design involving the evaluation of one leg hop for distance performance in a consecutive sample of 10 ACL deficient males with an isolated ACL tear awaiting reconstructive surgery and nine gender, age-matched controls.
In the ACL deficient, the hop index was associated with the distance hopped on the non-injured limb (r = -0.66, p = 0.04) but not on the injured limb. Transformation (logarithmic) of the hop distance scores and re-calculation of the hop index using the transformed scores increased the sensitivity of the hop index in the detection of functional limitations from 20 to 60% and 50 to 70% using the normal limb symmetry reference norms of > or = 85% and 90% respectively.
The distance hopped on the non-injured limb is a critical factor in detecting functional limitations using the hop index in patients with an ACL deficient knee. Logarithmic transformation of the hop distance scores minimizes the effect of the arithmetic differences between limbs however; the sensitivity of the hop index in detecting abnormal limb symmetry remains low.
The use of external ankle support is widespread throughout sports medicine. However, the application of ankle bracing to a healthy ankle over a long period has been scrutinised because of possible neuromuscular adaptations resulting in diminished dynamic support offered by the peroneus longus.
To investigate the immediate and chronic effects of ankle brace application on the amplitude of peroneus longus stretch reflex.
Twenty physically active college students (mean (SD) age 23.6 (1.7) years, height 168.7 (8.4) cm, and mass 69.9 (12.0) kg) who had been free from lower extremity pathology for the 12 months preceding the study served as subjects. None had been involved in a strength training or conditioning programme in the six months preceding the study. A 3 x 3 x 2 (test condition x treatment condition x time) design with repeated measures on the first and third factor was used. The peroneus longus stretch reflex (% of maximum amplitude) during sudden foot inversion was evaluated under three ankle brace conditions (control, lace up, and semi-rigid) before and after eight weeks of ankle brace use.
A 3 x 3 x 2 repeated measures analysis of variance showed that peroneus longus stretch reflex amplitude increased immediately after application of a lace up brace (67.1 (4.4)) compared with the semi-rigid (57.9 (4.3)) and control (59.0 (5.2)) conditions (p<0.05). Peroneus longus stretch reflex also increased after eight weeks of use of the semi-rigid brace compared with the lace up and control conditions (p<0.05).
Initial application of a lace up style ankle brace and chronic use of a semi-rigid brace facilitates the amplitude of the peroneus longus stretch reflex. It appears that initial and long term ankle brace use does not diminish the magnitude of this stretch reflex in the healthy ankle.
Prospective cohort.
To determine if Star Excursion Balance Test (SEBT) reach distance was associated with risk of lower extremity injury among high school basketball players.
Although balance has been proposed as a risk factor for sports-related injury, few researchers have used a dynamic balance test to examine this relationship.
Prior to the 2004 basketball season, the anterior, posteromedial, and posterolateral SEBT reach distances and limb lengths of 235 high school basketball players were measured bilaterally. The Athletic Health Care System Daily Injury Report was used to document time loss injuries. After normalizing for lower limb length, each reach distance, right/left reach distance difference, and composite reach distance were examined using odds ratio and logistic regression analyses.
The reliability of the SEBT components ranged from 0.82 to 0.87 (ICC3,1) and was 0.99 for the measurement of limb length. Logistic regression models indicated that players with an anterior right/left reach distance difference greater than 4 cm were 2.5 times more likely to sustain a lower extremity injury (P<.05). Girls with a composite reach distance less than 94.0% of their limb length were 6.5 times more likely to have a lower extremity injury (P<.05).
We found components of the SEBT to be reliable and predictive measures of lower extremity injury in high school basketball players. Our results suggest that the SEBT can be incorporated into preparticipation physical examinations to identify basketball players who are at increased risk for injury.
This brief review examines some of the methods used to infer central control strategies from surface electromyogram (EMG) recordings. Among the many uses of the surface EMG in studying the neural control of movement, the review critically evaluates only some of the applications. The focus is on the relations between global features of the surface EMG and the underlying physiological processes. Because direct measurements of motor unit activation are not available and many factors can influence the signal, these relations are frequently misinterpreted. These errors are compounded by the counterintuitive effects that some system parameters can have on the EMG signal. The phenomenon of crosstalk is used as an example of these problems. The review describes the limitations of techniques used to infer the level of muscle activation, the type of motor unit recruited, the upper limit of motor unit recruitment, the average discharge rate, and the degree of synchronization between motor units. Although the global surface EMG is a useful measure of muscle activation and assessment, there are limits to the information that can be extracted from this signal.
Context
Gluteus medius (GM) contraction during single-leg stance prevents the contralateral pelvis from “dropping,” providing stability for lower extremity motion.
Objective
To determine which combination of hip rotation and abduction exercise results in the greatest activity of the GM and whether the GM responds to increased loads in these exercises.
Design and Setting
Repeated measures, laboratory.
Subjects
20 healthy volunteers.
Interventions
Resistance (2.26 and 4.53 kg) was provided to 3 variations of a single-leg-stance exercise: hip abduction only, abduction-internal rotation (ABD-IR), and abduction-external rotation.
Measurements
Muscle activity was recorded from the anterior and middle portions of the GM using surface electromyography.
Results
ABD-IR produced the most activity in the anterior and middle sections of the GM muscle. The 4.53-kg load produced significantly more activity than the 2.26-kg load ( P < .05).
Conclusions
The GM is most active when performing abduction and internal rotation of the hip. This information could be used to develop GM-strengthening exercises.
Bracing and rehabilitation are common aspects of an ankle treatment regimen. Recent evidence suggests that bracing and taping are effective in restricting ankle motion to within normal inversion/eversion ranges. They also improve kinesthesia and neuromuscular response, and decrease the velocity of inversion movements. Rehabilitation studies suggest that strength and balance training of the uninjured limb may be useful in facilitating recovery of the injured limb. It has also been demonstrated that daily balance training using wobble boards reduces the risk of further injury. Copyright © 2004 by Elsevier Science (USA).
To evaluate the effect of soft and semirigid ankle orthoses on dynamic balance assessed using Star Excursion Balance Test in patients with functional ankle instability compared with healthy individuals.
Non-experimental, observational study with multiple-factor design, including group (functional ankle instability and healthy) as the between-subjects factor and orthotics condition (no orthosis, soft orthosis and semirigid orthosis) as the within-subjects factor.
Sixteen unilateral functional ankle instability patients and a group of 16 healthy control individuals, matched for age, height and weight, participated in the study. Dynamic balance was tested with and without wearing ankle orthosis. Reach distance of participants in 3 bracing conditions were measured in anteromedial, medial and posteromedial directions of Star Excursion Balance Test. Average of 3 trials in 3 measured directions, normalized to leg length of each participant, was used for statistical analysis.
There were no differences among orthotics conditions in healthy people. However, normalized reach distance increased from no-orthosis to semirigid to soft orthoses in FAI patients. Differences were significant between soft and no-orthosis (13% in anteromedial, 14% in medial and 15% in posteromedial direction p=0.01) and between semirigid and no-orthosis (10% in anteromedial, 8.5% in medial and 8.5% in posteromedial direction, p=0.01) conditions in all 3 measured directions. The difference between soft and semirigid orthoses was significant (6% difference, p<0.05) only in PM direction.
Ankle orthoses improve reach distance in functional ankle instability patients in various reach directions. Soft orthosis has a more pronounced effect on dynamic balance, especially in posteromedial direction, compared with semirigid orthosis.
Background
Groin pain is a common injury among football code athletes. The repetitive turning, twisting and kicking involved in such sports place supra-physiological stresses through the pelvic region. It has been suggested that rehabilitation of chronic groin pain requires specific sequencing of muscle activation to be effective. This has been identified as being a difference in subjects with groin and sacroiliac joint pain during lower limb movement.AimsThe aims of this paper were to; (1) identify any differences in muscle activation before and during an active straight leg raise between football code groin sufferers and controls and to (2) highlight any differences in muscle activity between the symptomatic and asymptomatic sides in the groin sufferers before and during an active straight leg raise.MethodologyNine subjects with groin pain and nine matched controls (matched according to age, weight and height) were used. Surface electromyogenic (EMG) electrodes were placed on six bilateral muscle groups – rectus femoris, biceps femoris, adductor longus, internal oblique, multifidus and gluteus medius. Movement was qualified with an active motion tracking system, while the subject lay on two force plates and performed an active straight leg raise manoeuvre. EMG, force and pelvic motion was analysed to demonstrate any muscle activation differences between the symptomatic and asymptomatic group.ResultsA significant difference was found between the symptomatic and asymptomatic limbs in both ipsilateral and contralateral adductor longus muscles (p
The anatomy of the hip abductors has not been comprehensively examined, yet is important to understanding function and pathology in the gluteal region. For example, pathology of the hip abductor muscle-tendon complexes can cause greater trochanteric pain syndrome, and may be associated with gluteal atrophy and fatty infiltration. The purpose of this study was to investigate the detailed morphology of gluteus medius (GMed), gluteus minimus (GMin), and tensor fascia lata (TFL), and determine whether the muscles comprised anatomical compartments. The gluteal region from 12 cadavers was dissected and data collected on attachment sites, volume, fascicular and tendinous anatomy, and innervation. Three sites of GMed origin were identified (gluteal fossa, gluteal aponeurosis, and posteroinferior edge of the iliac crest) and the distal tendon had lateral and posterior parts. GMed was the largest in volume (27.6 ± 11.6 cm(3) ; GMin 14.1 ± 11.1 cm(3) ; TFL 1.8 ± 0.8 cm(3) ). Fascicles of GMin originated from the gluteal fossa, inserting onto the deep surface of its distal tendon and the hip joint capsule. TFL was encapsulated in the fascia lata, having no bony attachment. Primary innervation patterns varied for GMed, with three or four branches supplying different regions of muscle. Distinct secondary nerve branches entered four regions of GMin; no differential innervation was observed for TFL. On the basis of architectural parameters and innervation, GMed, and GMin each comprise of four compartments but TFL is a homogenous muscle. It is anticipated that these data will be useful for future clinical and functional studies of the hip abductors. Clin. Anat. 00:000-000, 2013. © 2013 Wiley Periodicals, Inc.
Introduction Exercise programmes are used in the prevention and treatment of adductor-related groin injuries in soccer; however, there is a lack of knowledge concerning the intensity of frequently used exercises.
Objective Primarily to investigate muscle activity of adductor longus during six traditional and two new hip adduction exercises. Additionally, to analyse muscle activation of gluteals and abdominals.
Materials and methods 40 healthy male elite soccer players, training >5 h a week, participated in the study. Muscle activity using surface electromyography (sEMG) was measured bilaterally for the adductor longus during eight hip adduction strengthening exercises and peak EMG was normalised (nEMG) using an isometric maximal voluntary contraction (MVC) as reference. Furthermore, muscle activation of the gluteus medius, rectus abdominis and the external abdominal obliques was analysed during the exercises.
Results There were large differences in peak nEMG of the adductor longus between the exercises, with values ranging from 14% to 108% nEMG (p<0.0001). There was a significant difference between legs in three of the eight exercises (35–48%, p<0.0001). The peak nEMG results for the gluteals and the abdominals showed relatively low values (5–48% nEMG, p<0.001).
Conclusions Specific hip adduction exercises can be graded by exercise intensity providing athletes and therapists with the knowledge to select appropriate exercises during different phases of prevention and treatment of groin injuries. The Copenhagen Adduction and the hip adduction with an elastic band are dynamic high-intensity exercises, which can easily be performed at any training facility and could therefore be relevant to include in future prevention and treatment programmes.
Study design:
Within-subject, repeated-measures design.
Objectives:
To determine the influence of pelvis position and hip angle on activation of the hip abductors while performing the clam exercise.
Background:
Therapeutic exercises are regularly employed to strengthen the hip abductors to improve lower-limb and pelvis stability. While previous studies primarily have compared the activity of hip abductor muscles between various exercises, few studies have examined the influence of varying the techniques of particular exercises on the relative activation of hip abductor muscles. Such information could be used to facilitate appropriate exercise instruction.
Methods:
Muscle activation in 17 healthy, asymptomatic volunteers during 6 variations of the clam exercise was analyzed with surface electromyography. Electromyographic signals were recorded from the gluteus maximus, gluteus medius, and tensor fasciae latae. Normalized data were examined using 2-way, repeated-measures analyses of variance.
Results:
The magnitude of gluteus maximus and gluteus medius activation was significantly greater when the pelvis was in neutral rather than reclined. Furthermore, gluteus medius activation was greatest when the hip was flexed to 60°. Activation of the tensor fasciae latae was not influenced by pelvis position or hip angle.
Conclusion:
A neutral pelvis position is advocated to optimize recruitment of the gluteus maximus and gluteus medius during the clam exercise. Increasing the hip flexion angle increases activation of the gluteus medius. Tensor fasciae latae activity was relatively low and generally unaffected by variations of the clam exercise.
Symptomatic external snapping hip can be a long-standing condition affecting physical function in younger people between 15-40 years. Gluteal weakness has been suggested to be associated with the condition. The aim of this study was to investigate whether eccentric hip abduction strength is decreased in patients with external snapping hip compared with healthy matched controls, and to examine isometric hip abduction, adduction, extension, flexion, internal rotation, and external rotation in patients with external snapping hip and matched controls. Thirteen patients with external snapping hip were compared with 13 healthy matched controls in a cross-sectional study design. The mean age of the patients was 25.5 ± 3.4 years and the mean age of the controls was 25.6 ± 2.6 years. Eccentric and isometric strength were assessed with a handheld dynamometer, using reliable test procedures. Eccentric hip abduction strength was 16% lower in patients with external snapping hip compared with healthy matched controls (1.50 ± 0.47 Nm/kg versus 1.82 ± 0.48 Nm/kg, P = 0.01). No other strength differences were measured between patients and controls (P > 0.05). Eccentric hip abductor weakness was present in patients with symptomatic external snapping hip compared with healthy matched controls.
To determine the effect of ankle braces on kicking accuracy, speed, and agility in competitive, nonelite soccer players. We hypothesized that the use of ankle bracing would significantly decrease performance in soccer-specific drills immediately after use but not after acclimation to the brace.
A prospective randomized controlled trial.
University.
Twenty healthy recreational adult soccer players (5 men and 15 women; mean age, 23 ± 4.8 years) without a history of lower extremity injury in the past 6 months. All the subjects completed the study.
The subjects completed a set of performance measures (ie, accuracy shooting at a target, 40-yard dash, S180° run, and T test) with an McDavid 199 Lightweight ankle brace (test subjects) and without an ankle brace (control subjects) during 2 testing sessions spaced 7-10 days apart. Between the 2 testing sessions, the subjects wore the ankle brace on at least 4 occasions while participating in athletic activities to ensure that a learning effect occurred.
Outcomes included kicking accuracy (accuracy shooting at a target) and speed and agility (time to complete a 40-yard dash, S180° run, and T test).
No significant difference in performance was found for the accuracy in shooting at a target, 40-yard dash, S180° run, and T test (P > .05) with and without an ankle brace during a session and between sessions.
Ankle braces did not significantly affect performance in speed, agility, or kicking accuracy in healthy, competitive, recreational soccer athletes.
Guidelines for assessing the function of gluteus minimus and gluteus medius with electromyography (EMG) traditionally offer one electrode placement site per muscle. However, anatomical studies suggest that there are two uniquely oriented segments within gluteus minimus (anterior and posterior), and three within gluteus medius (anterior, middle, and posterior) with potential for independent function. Assessment of these muscles with one electrode may therefore provide only a limited account of their role. Thus, the aim of this cadaveric study was to verify guidelines for placing intramuscular electrodes into two uniquely oriented segments of gluteus minimus, and three segments of gluteus medius. The guidelines were developed with reference to anatomical reports, cadaveric observation and real-time ultrasound imaging in vivo. Five cadaveric gluteal regions were marked for intramuscular electrode insertions based on these guidelines. Intramuscular electrodes were inserted into the marked regions of gluteus minimus (2×) and gluteus medius (3×) with the aid of a 15 cm biopsy needle. Systematic dissection revealed that electrodes were successfully inserted into uniquely oriented segments of gluteus minimus and medius. The orientation of fascicles surrounding each electrode was also consistent with segmental descriptions in past anatomical research. The findings of this research suggest that the guidelines described may be used to assess the functional role of segments within gluteus minimus and medius in health and dysfunction using EMG. Finally, electromyographers intent on investigating the role of posterior gluteus minimus must be cautious of the superior gluteal neurovascular bundle. Clin. Anat., 2012. © 2012 Wiley Periodicals, Inc.
Functional subdivisions are proposed to exist in the gluteus medius (GM) muscle. Dysfunction of the GM, in particular its functional subdivisions, is commonly implicated in lower limb pathologies. However, there is a lack of empirical evidence examining the role of the subdivisions of the GM.
To compare the activation of the functional subdivisions of the GM (anterior, middle, and posterior) during isometric hip contractions.
Single-session, repeated-measures observational study.
University research laboratory.
Convenience sample of 15 healthy, pain-free subjects.
Subjects performed 3 maximal voluntary isometric contractions for hip abduction and internal and external rotation on an isokinetic dynamometer with simultaneous recording of surface electromyography (sEMG) activity of the GM subdivisions.
sEMG muscle activity for each functional subdivision of the GM during each hip movement was analyzed using a 1-way repeated-measures ANOVA (post hoc Bonferroni).
The response of GM subdivisions during the 3 different isometric contractions was significantly different (interaction effect; P = .003). The anterior GM displayed significantly higher activation across all 3 isometric contractions than the middle and posterior subdivisions (main effect; both P < .001). The middle GM also demonstrated significantly higher activation than the posterior GM across all 3 isometric contractions (main effect; P = .027). There was also significantly higher activation of all 3 subdivisions during both abduction and internal rotation than during external rotation (main effect; both P < .001).
The existence of functional subdivisions in the GM appears to be supported by the findings. Muscle activation was not homogeneous throughout the entire muscle. The highest GM activation was found in the anterior GM subdivision and during abduction and internal rotation. Future studies should examine the role of GM functional subdivisions in subjects with lower limb pathologies.
An ipsilateral hip adduction/abduction strength ratio of more than 90%, and hip adduction strength equal to that of the contralateral side have been suggested to clinically represent adequate strength recovery of hip adduction strength in athletes after groin injury. However, to what extent side-to-side symmetry in isometric hip adduction and abduction strength can be assumed in soccer players remains uncertain.
To compare isometric hip adduction and abduction strength on the dominant and nondominant side in injury-free soccer players.
Cross-sectional study; Level of evidence, 3.
One hundred elite soccer players were included. Maximal unilateral isometric hip adduction and abduction strength on the dominant and nondominant side were measured with a handheld dynamometer, using a reliable test procedure.
The dominant side was stronger than the nondominant side for both isometric hip adduction (2.45 ± 0.54 vs 2.37 ± 0.48 Nm/kg, P = .02) and hip abduction (2.35 ± 0.33 vs 2.25 ± 0.31 Nm/kg, P < .001), corresponding to a 3% and 4% difference, respectively. Isometric hip adduction was greater than isometric hip abduction for both the dominant (2.44 ± 0.53 vs 2.35 ± 0.33 Nm/kg, P = .04) and nondominant (2.37 ± 0.48 vs 2.26 ± 0.33 Nm/kg, P = .03) side. Isometric hip adduction/abduction ratio was not different between the dominant (1.04 ± 0.18) and nondominant (1.06 ± 0.17, P = .40) side. A post hoc analysis showed that isometric hip adduction/abduction ratio was significantly lower in players with groin pain during hip adduction testing compared with players with a pain-free test (0.80 ± 0.14, P < .001)
The marginal difference between the dominant and the nondominant side is within the measurement variation of the test procedure, and contralateral isometric hip adduction strength can therefore be used as a simple clinical reference point of full recovery of hip adduction muscle strength in soccer players. Furthermore, it is suggested that the ipsilateral hip adduction/abduction strength ratio is used as a guideline for evaluating hip adduction strength recovery in soccer players with bilateral groin problems.
The side-lying hip abduction exercise is one of the most commonly used exercises in rehabilitation to increase hip abduction strength, and is often performed without external loading. The aim of this study was to compare the effect of 6 weeks of side-lying hip abduction training, with and without external loading, on hip abduction strength in healthy subjects. Thirty-one healthy, physically active men and women were included in a randomised controlled trial and allocated to side-lying hip abduction training, with or without external loading. Training without external loading was performed using only the weight of the leg as resistance, whereas training with external loading was performed with a relative load corresponding to 10 repetition maximum. Hip abduction strength was measured pre- and post-intervention. Isometric and eccentric hip abduction strength of the trained leg increased after hip abduction training with external loading by 12% and 17%, respectively, (P<0.05). Likewise, isometric and eccentric hip abduction strength of the trained leg increased after hip abduction training without external loading by 11% and 23%, respectively, (P<0.001). The strength increases were not different between groups (P>0.05). Six weeks of side-lying hip abduction training, with or without external loading, increases isometric and eccentric hip abduction strength to the same extent.
The purpose of this study was to determine the effect of prophylactic ankle bracing on the incidence of ankle injuries in a high school population of interscholastic volleyball players followed prospectively for one season.
The study was designed to evaluate the effect of different types of ankle braces on the incidence of ankle sprains in high school volleyball players. There were 957 players in the group that wore braces and 42 in the control group who did not wear a brace. Information was collected on age, sex, previous injury, incidence of injury, and time off from play. Only the dominant ankle was studied.
Overall, the use of a prophylactic ankle brace did not significantly alter the incidence of ankle sprains in high school volleyball players. However, in players without a previous ankle sprain, the use of an ankle brace did make a significant difference in two of the braced groups. The Active Ankle Trainer II and the Aircast Sports Stirrup protected volleyball players from a sprain only if they had not had a previous sprain. If the player had a history of a previous ankle sprain, these two brace groups did not protect the ankle from another ankle sprain (p < 0.05). In addition, there were significantly more injuries in the female group of players who wore a non-rigid brace versus those who wore a more rigid brace.
This information may be helpful in deciding whether to recommend prophylactic ankle braces in volleyball players.
Hip strength assessment plays an important role in the clinical examination of the hip and groin region. The primary aim of this study was to examine the absolute test-retest measurement variation concerning standardized strength assessments of hip abduction (ABD), adduction (ADD), external rotation (ER), internal rotation (IR), flexion (FLEX) and extension (EXT) using a hand-held dynamometer. Nine subjects (five males, four females), physically active for at least 2.5 h a week, were included. Twelve standardized isometric strength tests were performed twice with a 1-week interval in between by the same examiner. The test order was randomized to avoid systematic bias. Measurement variation between sessions was 3-12%. When the maximum value of four measurements was used, test-retest measurement variation was below 10% in 11 of the 12 individual hip strength tests and below 5% in five of the 12 tests. No systematic differences were present. Standardized strength assessment procedures of hip ABD, ER, IR, FLEX, with test-retest measurement variation below 5%, hip ADD below 6% and hip EXT below 8%, make it possible to determine even small changes in hip strength at the individual level.
The purpose of this randomized controlled trial was to determine the effect of a 4-wk balance training program on static and dynamic postural control and self-reported functional outcomes in those with chronic ankle instability (CAI).
Thirty-one young adults with self-reported CAI were randomly assigned to an intervention group (six males and 10 females) or a control group (six males and nine females). The intervention consisted of a 4-wk supervised balance training program that emphasized dynamic stabilization in single-limb stance. Main outcome measures included the following: self-reported disability on the Foot and Ankle Disability Index (FADI) and the FADI Sport scales; summary center of pressure (COP) excursion measures including area of a 95% confidence ellipse, velocity, range, and SD; time-to-boundary (TTB) measures of postural control in single-limb stance including the absolute minimum TTB, mean of TTB minima, and SD of TTB minima in the anteroposterior and mediolateral directions with eyes open and closed; and reach distance in the anterior, posteromedial, and posterolateral directions of the Star Excursion Balance Test (SEBT).
The balance training group had significant improvements in the FADI and the FADI Sport scores, in the magnitude and the variability of TTB measures with eyes closed, and in reach distances with the posteromedial and the posterolateral directions of the SEBT. Only one of the summary COP-based measures significantly changed after balance training.
Four weeks of balance training significantly improved self-reported function, static postural control as detected by TTB measures, and dynamic postural control as assessed with the SEBT. TTB measures were more sensitive at detecting improvements in static postural control compared with summary COP-based measures.
We evaluated the effect of different ankle support de vices on athletic performance. Thirty varsity college athletes were tested with both ankles supported by taping, Swede-O brace, Kallassy brace or left unsup ported. The athletes performed four events: broad jump, vertical leap, 10 yard shuttle run, and 40 yard sprint. The events and appliances were randomized to prevent bias by fatigue.
Compared to the results when no support was used, ankle taping resulted in a significant decreased perform ance in the vertical jump (4%), shuttle run (1.6%), and sprint (3.5%) (P < 0.05). Use of the Swede-O brace decreased performance in the vertical jump (4.6%), broad jump (3.6%), and time of the sprint (3.2%). Re sults using the Kallassy brace showed a decrease in the vertical jump (3.4%) when compared to no support. The test results of the shuttle run with taping were slower than the Kallassy brace (P < 0.05). Wearing the Swede-O brace caused the athletes' broad jump dis tance to decrease more than the Kallassy brace (P < 0.05). Subjective questionnaires supported the Kallassy brace as the most comfortable support and the one that decreased performance the least.
Taping of the ankles is universally accepted for ankle prophylaxis. This study has shown a decrease in per formance when ankles are taped compared to ankles with no protection. Since the decreases in performance caused by ankle braces are minor, this should not be used as a criterion for selection of prophylactic support compared to taping.
The purpose of this study was to compare the relative effectiveness of athletic taping and a semirigid orthosis in providing inversion-eversion range restriction before, during, and after a 3 hour volleyball practice. The effect of each support method on the subjects' vertical jumping ability was also assessed. Fourteen ankles were treated with both methods of support. Passive inversion-eversion range of motion was measured on an ankle stability test instrument during five testing sessions: 1) before support, 2) before exercise, 3) 20 minutes during exercise, 4) 60 minutes during exercise, and 5) after exercise. The two-way analysis of variance and posthoc comparisons revealed maximal losses in taping restriction for both inversion and eversion at 20 minutes into exercise. The orthosis demonstrated no mechanical restrictive failure until before and after exercise comparisons were made, and then only eversion range of motion was compromised. Neither support system affected subjects' vertical jumping ability. These results suggest that the semirigid orthosis may be more effective than taping in providing initial ankle protection and in guarding against ligamentous reinjury.
The effects of ankle guards and taping on joint motion before, during, and after exercise were studied. Twelve league squash players played two matches, each lasting 1 hour. Two different ankle guards, and two types of tape applied by the same method, served as supports. A specially designed goniometer with electronic digital display (accuracy 1 degree) was used to determine joint range of motion: plantar-flexion and dorsiflexion, neutral inversion and eversion, plantar-flexed inversion and eversion. The results were statistically analyzed to determine the significance of the restriction provided by the supports. This revealed that the two ankle guards provided no significant support. The two tapes, however, provided significant support before exercise and after 10 minutes but not after 1 hour of exercise. Nonelastic (zinc oxide) tape proved to be the most restrictive at all times measured, especially prior to exercise, when the ankle's range of motion was decreased between 30% and 50%. However, once exercise commenced, the tape stretched, and restriction became less effective.
The identification of a quantifiable dose-response relationship for strength training is important to the prescription of proper training programs. Although much research has been performed examining strength increases with training, taken individually, they provide little insight into the magnitude of strength gains along the continuum of training intensities, frequencies, and volumes. A meta-analysis of 140 studies with a total of 1433 effect sizes (ES) was carried out to identify the dose-response relationship.
Studies employing a strength-training intervention and containing data necessary to calculate ES were included in the analysis.
ES demonstrated different responses based on the training status of the participants. Training with a mean intensity of 60% of one repetition maximum elicits maximal gains in untrained individuals, whereas 80% is most effective in those who are trained. Untrained participants experience maximal gains by training each muscle group 3 d.wk and trained individuals 2 d.wk. Four sets per muscle group elicited maximal gains in both trained and untrained individuals.
The dose-response trends identified in this analysis support the theory of progression in resistance program design and can be useful in the development of training programs designed to optimize the effort to benefit ratio.
The purpose of this study was to quantify the contributions made by individual muscles to support of the whole body during normal gait. A muscle's contribution to support was described by its contribution to the time history of the vertical force exerted by the ground. The analysis was based on a three-dimensional, muscle-actuated model of the body and a dynamic optimization solution for normal walking. The results showed that, in early stance, before the foot was placed flat on the ground, support was provided mainly by the ankle dorsiflexors. After foot-flat, but before contralateral toe-off, support was generated primarily by gluteus maximus, vasti, and posterior gluteus medius/minimus; these muscles were responsible for the first peak seen in the vertical ground-reaction force. The majority of support in midstance was provided by gluteus medius/minimus, with gravity assisting significantly as well. The ankle plantarflexors generated nearly all support in late stance; these muscles were responsible for the second peak in the vertical ground-reaction force. The results showed also that centrifugal forces act to decrease the vertical ground-reaction force, but only by minor amounts, and that resistance of the skeleton to the force of gravity is no larger than 1/2 body weight throughout the gait cycle.
Case report.
To describe an alternative treatment approach for patellofemoral pain.
Weakness of the hip, pelvis, and trunk musculature has been hypothesized to influence lower-limb alignment and contribute to patellofemoral pain. Two patients who had a chief complaint of patellofemoral pain and demonstrated lack of control of the hip in the frontal and transverse planes during functional movements were treated with an exercise program targeting the hip, pelvis, and trunk musculature.
The patients presented in these 2 case reports did not exhibit obvious patellar malalignment or tracking problems; however, on qualitative assessment, both demonstrated excessive hip adduction, internal rotation, and knee valgus during gait and while performing a step-down maneuver. In addition, both patients exhibited weakness of the hip abductors, extensors, and external rotators, as demonstrated by hand-held dynamometry testing. Treatment in both cases occurred over a 14-week period and focused on recruitment and endurance training of the hip, pelvis, and trunk musculature. Functional status, pain, muscle force production, as well as subjective and objective assessment of lower-extremity kinematics during gait and a step-down maneuver were assessed preintervention and postintervention.
Both patients experienced a significant reduction in patellofemoral pain, improved lower-extremity kinematics during dynamic testing, and were able to return to their original levels of function. Gluteus medius force production improved by 50% in patient A and 90% in patient B, while gluteus maximus force production improved 55% in patient A and 110% in patient B. Objective kinematic improvements in the step-down task also were demonstrated in patient A.
Assessment and treatment of the hip, pelvis, and trunk musculature should be considered in the rehabilitation of patients who present with patellofemoral pain and demonstrate abnormal lower-extremity kinematics.
To determine if timed balance scores on the modified Clinical Test of Sensory Interaction and Balance (CTSIB) were affected by shoe wear in patients with balance and vestibular disorders and to determine if there is a difference in correlation with the Sensory Organization Test (SOT) or in the sensitivity or specificity based on footwear.
Prospective correlational trial.
Outpatient clinic.
Thirty persons (mean age, 63+/-17 y) currently undergoing vestibular physical therapy (PT).
All subjects completed the modified CTSIB with their shoes on and off at the end of a PT session; 16 of them (53%) also completed the SOT on the same day.
Scores on the modified CTSIB and SOT.
No difference existed between scores on the modified CTSIB with shoes on versus off. Similar correlation was found between the modified CTSIB performed with the shoes on and off and SOT scores. The sensitivity and specificity of the modified CTSIB was similar with shoes on and off.
The modified CTSIB can be performed with or without shoes, with no difference expected in patient score or test sensitivity or specificity.
Based on the recent suggestion that proximal hip control may be related to a predisposition to anterior cruciate ligament injury, our purpose was to identify gender differences in hip mechanics between female athletes who previously demonstrated greater knee valgus moments and their male counterparts.
Descriptive laboratory study.
Testing was conducted in a biomechanics research laboratory.
Thirty collegiate soccer players (15 women and 15 men) participated in this study. All subjects were healthy with no current complaints of lower extremity injury.
Three-dimensional hip joint kinematics and kinetics were collected while subjects performed a side-step cutting maneuver. Gender differences in hip mechanics were compared using independent sample t tests.
Compared with male athletes, female athletes demonstrated significantly greater hip internal rotation and decreased hip flexion. In addition, female athletes demonstrated significantly greater hip adductor moments as well as decreased hip extensor moments.
Overall, it appeared that female athletes moved into greater hip internal rotation and used less sagittal plane hip motion during the early deceleration phase of the cutting maneuver. The findings of this investigation support the premise that altered hip kinematics and kinetics may influence loading at the knee. Future studies are needed to further explore the impact of these differences on knee loading and to ascertain the underlying causes.
A comparison of electromyographic (EMG) activity of muscles between and within subjects, and during separate occasions of testing, requires normalization. The most common way for generating the reference level used for normalizing shoulder EMG data is with a maximum isometric voluntary contraction (MVIC). The purpose of this study was to develop a parsimonious set of standardized tests that generate an MVIC in all the major muscle groups of the shoulder. Twelve muscles of the dominant shoulder of 15 subjects were examined using a combination of surface and intramuscular electrodes during 15 tests. The results indicated that many tests maximally activated more than one muscle simultaneously. Four tests were identified as being sufficient for generating an MVIC in the 12 muscles examined and are recommended as the standard set for normalizing shoulder muscle EMG: abduction 90 degrees with internal rotation ("empty can"), internal rotation in 90 degrees abduction ("internal rotation 90 degrees"), flexion at 125 degrees with scapula resistance ("flexion 125 degrees"), and horizontal adduction at 90 degrees flexion ("palm press"). The use of these shoulder normalization tests will make comparisons between shoulder EMG studies more reliable.