Electromyographic analysis of gluteus maximus and hamstring activity during the supine resisted hip extension exercise versus supine unilateral bridge to neutral

Hip extension strengthening exercises which maximize gluteus maximus contributions and minimize hamstring influences may be beneficial for persons with hip pain. This study’s aim was to compare muscle activation of the gluteus maximus and hamstrings from healthy subjects during a supine resisted hip extension exercise versus supine unilateral bridge to neutral. Surface electromyographic (EMG) signals were obtained from the right gluteus maximus and hamstrings in 13 healthy male and 13 healthy female subjects. Maximum voluntary isometric contractions (MVICs) were collected to normalize data and permit meaningful comparisons across muscles. Peak median activation of the gluteus maximus was 33.8% MVIC for the bridge and 34.7% MVIC for the hip extension exercise, whereas peak median recruitment for hamstrings was 28.4% MVIC for the bridge and 51% MVIC for the hip extension exercise. The gluteus maximus to hamstrings ratio was compared between the two exercises using the Wilcoxon signed-ranks test (α = 0.05). The ratio (p = 0.014) was greater in the supine unilateral bridge (median = 111.3%) than supine hip extension exercise (median = 59.2%), suggesting a reduction of hamstring recruitment in the unilateral bridge to neutral compared to the supine resisted hip extension exercise. The supine hip extension exercise demonstrated higher EMG activity of hamstrings in comparison with supine unilateral bridge and, therefore, may be less appropriate in subjects who need to increase gluteus maximus activation.     

Effects of abdominal drawing-in during prone hip extension on the muscle activities of the hamstring,gluteus maximus,and lumbar erector spinae in subjects with lumbar hyperlordosis

[Purpose] The purpose of this study was to compare the effects of an abdominal drawing-in maneuver (ADIM), measured using a pressure bio-feedback unit, on the activities of the hamstring, gluteus maximus, and erector spinae muscles during prone hip extension. [Subjects and Methods] Thirty healthy adult subjects (14 male, 16 female), were recruited. Subjects’ lumbar lordosis and pelvic tilt angles were measured, and based on the results, the subjects were divided into two groups: a hyperlordotic lumbar angle (HLLA) group (n=15) and a normal lordotic lumbar angle (NLLA) group (n=15). The muscle activities of the hamstring and gluteus maximus, and of the erector spinae on the right side of the body, were recorded using surface electromyography. [Results] When performing ADIM with prone hip extension, the muscle activity of the gluteus maximus of the HLLA group significantly improved compared with that the NLLA group. [Conclusion] This study demonstrated that ADIM with prone hip extension was more effective at eliciting gluteus maximus activity in the HLLA group than in the NLLA group. Therefore, ADIM with prone hip extension may be useful for increasing the gluteus maximus activity of individuals with lumbar hyperlordosis.Key words: Abdominal drawing-in maneuver, Hyperlordotic lumbar angle, Prone hip extension     

Editorial

Abstract

The aim of this study was to compare the magnitude of selective core muscle activation during supine bridging to neutral exercises (three on a stable and three on an unstable surface). Surface EMG analysis was performed on the lumbar multifidus, gluteus medius, gluteus maximus, and hamstrings from 13 male and 13 female subjects. Lumbar multifidus recruitment was not influenced by exercise or condition and ranged between 29.2 and 35.9% of maximum voluntary isometric contraction (MVIC). Peak gluteus medius activation (42.0% MVIC) occurred in unstable single-leg bridge. Maximum recruitment of gluteus maximus (32.6% MVIC) appeared during stable single-leg bridge. Peak hamstring activation (59.6% MVIC) occurred during stable double-leg hamstring curl. Regardless of condition, hamstrings demonstrated high (51.9–59.6% MVIC) muscle recruitment during double-leg hamstring curls compared with the single-leg bridge or double-leg bridge. Various supine bridging to neutral exercises activated the hamstrings at levels conducive to strengthening, whereas recruitment of lumbar multifidus, gluteus medius, and gluteus maximus promoted endurance training. Clinically, we were unable to conclude the unstable support surface was preferable to the stable surface for boosting muscle recruitment of spine stabilizers, gluteals, and hamstring muscles during supine bridge to neutral position.     

EFFECT OF RESTRICTED HIP FLEXOR MUSCLE LENGTH ON HIP EXTENSOR MUSCLE ACTIVITY AND LOWER EXTREMITY BIOMECHANICS IN COLLEGE‐AGED FEMALE SOCCER PLAYERS

Background

Hip flexor tightness is theorized to alter antagonist muscle function through reciprocal inhibition and synergistic dominance mechanisms. Synergistic dominance may result in altered movement patterns and increased risk of lower extremity injury.

Hypothesis/Purpose

To compare hip extensor muscle activation, internal hip and knee extension moments during double‐leg squatting, and gluteus maximus strength in those with and without clinically restricted hip flexor muscle length.

Design

Causal‐comparative cross‐sectional laboratory study.

Method

Using a modified Thomas Test, female soccer athletes were assigned to a restricted (>0 ° of sagittal plane hip motion above the horizontal; n=20, age=19.9 ± 1 years, ht=167.1 ± 6.4 cm, mass=64.7 ± 8.2kg) or normal (>15 ° of sagittal plane hip motion below horizontal; n=20, age=19.4 ± 1 years, ht=167.2 ± 5.5 cm, mass=61.2 ± 8.6 kg) hip flexor muscle length group. Surface electromyographic (sEMG) activity of the gluteus maximus and biceps femoris, and net internal hip and knee extension moments were measured between groups during a double‐leg squat. Isometric gluteus maximus strength was assessed using handheld dynamometry.

Results

Individuals with restricted hip flexor muscle length demonstrated less gluteus maximus activation (p=0.008) and a lower gluteus maximus : biceps femoris co‐activation ratio (p=0.004). There were no significant differences (p>0.05) in hip or knee extension moments, isometric gluteus maximus strength, or biceps femoris activation between groups.

Conclusions

Female soccer athletes with hip flexor muscle tightness exhibit less gluteus maximus activation and lower gluteus maximus : biceps femoris co‐activation while producing similar net hip and knee extension moments. Thus, individuals with hip flexor muscle tightness appear to utilize different neuromuscular strategies to control lower extremity motion.

Level of Evidence

3     

Is neuromuscular inhibition detectable in elite footballers during the Nordic hamstring exercise?

BackgroundThe presence of neuromuscular inhibition following injury may explain the high incidence of biceps femoris injury recurrence in elite (soccer) footballers. This phenomenon may be detectable in elite players during the Nordic hamstring exercise. Thus, the first purpose of this study was to assess biceps femoris muscle activation during this exercise in players with hamstring injury history. Additionally, following injury, observed increases in synergistic muscle activation may represent a protective mechanism to the presence of neuromuscular inhibition. Thus, the second purpose was to identify if the relative contributions of biceps femoris, and its synergists reflected a post-injury pattern of activation suggestive of these potentially compensatory neural mechanisms.MethodsTen elite players with a history of hamstring injury and ten elite players without a history of hamstring injury, completed six repetitions of the Nordic hamstring exercise. During each trial, biceps femoris, semitendinosus and gluteus maximus muscle activations were collected at 90–30° and 30–0° of knee flexion.FindingsBiceps femoris activation was significantly higher at 90–30° of knee flexion compared to 30–0° (P < 0.001) but did not differ between the groups. In players with a history of injury, muscle activation ratios for the biceps femoris/semitendinosus (P = 0.001) and biceps femoris/gluteus maximus (P = 0.023) were significantly greater at 30–0° of knee flexion than in the control group.InterpretationNeuromuscular inhibition of the biceps femoris was not detected during the exercise within elite footballers, yet the relative contributions of biceps femoris and its synergists appear to change following injury.     

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.     

Effect of Mobilization of the Anterior Hip Capsule on Gluteus Maximus Strength

Abstract

Loss of hip extension is often compensated for by extension of the lumbar spine. This compensation can result in hypermobility and ultimately be a source of low back dysfunction and pain. Joint mobilizations have been known to return physiologic and accessory motion to hypomobile structures. Mobilization has also been demonstrated to improve muscular strength when secondary to joint hypomobility. The purpose of this study was to determine the usefulness of posteroanterior (P-A) hip-joint mobilization in improving strength of the gluteus maximus muscle. Forty subjects were randomly assigned to a control group (Grade I P-A mobilization) and an experimental group (Grade IV P-A mobilization). The subjects performed a pretest/posttest set of five isometric repetitions on the Cybex Norm? isokinetic machine. The peak torque was determined for both pretest and posttest measurements. The data collected were analyzed using an independent t-test with a significance level of p < .05. The results demonstrated a statistically significant difference between the experimental and control groups (t=1.68, p=0.002). This study demonstrated a significant increase in gluteus maximus strength in response to Grade IV P-A mobilizations performed on the anterior hip capsule. Clinicians can utilize these findings in everyday practice to improve muscle strength by integrating manual therapy with therapeutic exercise.     

Gluteal Muscle Activation During Common Yoga Poses

BackgroundApproximately 24% of physical therapists report regularly using yoga to strengthen major muscle groups. Although clinicians and athletes often use yoga as a form of strength training, little is known about the activation of specific muscle groups during yoga poses, including the gluteus maximus and medius.Hypothesis/PurposeThe purpose of this study was to measure gluteus maximimus and gluteus medius activation via electromyography (EMG) during five common yoga poses. A secondary purpose of the current study was to examine differences in muscle activation between sexes and experience levels.Study DesignCross-SectionalMethodsThirty-one healthy males and females aged 18-35 years were tested during five yoga poses performed in a randomized order. Surface EMG electrodes were placed on subjects’ right gluteus maximus and gluteus medius. Subjects performed the poses on both sides following a maximal voluntary isometric contraction (MVIC) test for each muscle. All yoga pose EMG data were normalized to the corresponding muscle MVIC data.ResultsHighest gluteus maximus activation occurred during Half Moon Pose on the lifted/back leg (63.3% MVIC), followed by the stance/front leg during Half Moon Pose (61.7%), then the lifted/back leg during Warrior Three Pose (46.1%). Highest gluteus medius activation occurred during Half Moon Pose on the lifted/back leg (41.9%), followed by the lifted/back leg during the Warrior Three Pose (41.6%). A significant difference was found in %MVIC of gluteus medius activity between male and female subjects (p = 0.026), and between experienced and inexperienced subjects (p = 0.050), indicating higher activation among males and inexperienced subjects, respectively.ConclusionHalf Moon Pose and Warrior Three Pose elicited the highest activation for both the gluteus maximus and the gluteus medius. Higher gluteus medius activation was seen in males and inexperienced subjects compared to their female and experienced counterparts.Level of Evidence3     

Activation of the gluteus maximus,gluteus medius and tensor fascia lata muscles during hip internal and external rotation exercises at three hip flexion postures

BackgroundHip internal and external rotation exercises are usually performed in clinical practice. However, given the synergies required to stabilize the hip in the frontal plane, it is not clear how the activation of target muscles will differ between the two exercise directions.ObjectiveI) Compare the activation of the upper and lower fibers of gluteus maximus (GMax), gluteus medius (GMed) and tensor fascia lata muscles between the hip internal and external rotation exercises; ii) Compare the maximal isometric force between hip internal and external rotation exercises and; iii) Assess the effect of varying hip flexion angles on muscle activation and maximal isometric force.Study designA cross sectional study.MethodsElectromyography and force production of twenty-one participants were measured during maximum isometric hip internal and external rotation in three postures: 0°, 45° and 90° of hip flexion.ResultsMANOVA results showed a larger activation of the GMed, tensor fascia lata and upper GMax (p < .001) for hip internal rotation compared to external rotation regardless of hip flexion angle. For the lower GMax, the same was observed when the hip was kept at 90° of flexion. Maximal isometric force during hip external rotation was greater than during hip internal rotation at 0° posture, and lower at 90° posture (p < .001).ConclusionThe gluteus and the tensor fascia lata muscles were substantially recruited during the hip internal rotation exercise, and barely recruited during the hip external rotation exercise. Hip flexion influences the myoeletric activity and isometric force production during the internal rotation exercise.     

Comparison between side-lying and standing positions for hip abductor strength assessment

BackgroundThe hip abductor muscles control the pelvis in the frontal plane and allow the maintenance of trunk position and dynamic balance during weight-bearing activities.ObjectiveTo compare the side-lying and standing positions for hip abductor strength assessment with regards to torque production and myolectric activity.MethodConcentric and eccentric hip abductor peak torque and total work, and myoelectric activity of the tensor fascia lata, gluteus medius, and inferior and superior portions of the gluteus maximus muscles were measured during maximal isokinetic tests for hip abductor strength in the side-lying and standing positions. The Wilcoxon test was used to compare variables between the positions.ResultsPeak torque values did not differ between side-lying and standing positions for both concentric and eccentric contraction modes (p > .05). During standing position, greater concentric total work was observed (p = .013). This position resulted in a lower activity of the tensor fascia lata muscle (p = .005) compared to side lying position. Myoelectric activity of gluteus medius, and inferior and superior portions of the gluteus maximus was similar between positions (p > .05).ConclusionBoth positions presented similar peak torque values and, during the standing position, a greater concentric total work and lesser activation of the tensor fascia lata was observed. Standing position can be used when emphasis on the superior portion of gluteus maximus over the tensor fascia lata is intended.     

Comparison of hip extensor muscle activity including the adductor magnus during three prone hip extension exercises

Objectives: This study compared the role of the adductor magnus muscle (Amag) as a hip extensor while performing active prone hip extension (PHE), PHE with hip adduction (PHE-ADD), and PHE with hip abduction (PHE-ABD) with the gluteus maximus (Gmax) and hamstrings. Methods: The study recruited 22 healthy participants. Electromyography data were recorded from the Amag, Gmax, and medial and lateral hamstrings during PHE, PHE-ADD, and PHE-ABD. Normalized electromyographic data were examined using one-way, repeated-measures analyses of variance. Results: The magnitude of the Amag, Gmax, and hamstring activations did not differ significantly while performing PHE (p = 0.41). Furthermore, the Amag and hamstring activations were significantly greater than the Gmax activation when performing PHE-ADD (p < 0.05). The Gmax showed significantly greater activation during PHE-ABD than the Amag and medial and lateral hamstrings (p < 0.05). Conclusions: Based on these results, we advocate including the Amag as a hip extensor during the PHE test or exercise. Our preliminary results have the potential to be applied directly to the PHE test, for investigating the muscle-activation pattern of the Amag with the Gmax and hamstrings in patients with hip or lower back pain.     

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.     

The influence of increasing sacroiliac joint force closure on the hip and lumbar spine extensor muscle firing pattern

The prone hip extension (PHE) test is commonly used in the evaluation of lumbo-pelvic dysfunction. It has been suggested that altered motor control identified by the PHE test can be improved with the application of compression force across the pelvis, to increase force closure on the sacroiliac joint (SIJ). This repeated measure study design investigated the effect of three levels of pelvis compression (0 N, 50 N, 100 N) on the muscle firing pattern during the PHE test in 20 asymptomatic male subjects tested on two occasions 4-weeks apart. The right gluteus maximus, right semitendinosus and bilateral lumbar erector spinae were analyzed using surface electromyography (EMG). Subjects were instructed to perform right hip extension in prone position while maintaining knee-extension in each measurement condition. Compared with the onset of the semitendinosus muscle, gluteus maximus became active 263.3 ± 99.5 ms later with no pelvic compression, 183.5 ± 77.9 ms later with 50 N compression, 91.5 ± 49.7 ms later with 100 N compression. While significant differences (α = 0.05) were found in EMG onset for gluteus maximus under different levels of pelvis compression, this was not the case for the erector spinae, which had an inconsistent pattern of temporal onset and was not influenced by the level of pelvis compression force.     

Timing and relative intensity of hip extensor and abductor muscle action during level and stair ambulation. An EMG study

The timing and relative intensity of electromyographic activity of hip abductor and extensor muscles were recorded during free and fast velocity walking and during ascent and descent of stairs. Eleven healthy subjects were tested using fine wire electrodes to record the electromyographic activity. Data were quantified by normalizing all electromyographic activity during gait with electromyographic activity occurring during a sustained maximum isometric effort resisted either manually or with a dynamometer. The results indicated that the hip extensor muscles had different phasic patterns and moments of peak activity. During level walking, the semimembranosus and long head of the biceps femoris muscles displayed the greatest swing phase activity (beginning in mid-swing). The adductor magnus muscle followed with its onset in terminal swing. Both this muscle and the gluteus maximus were the principal hip extensors active during the loading response. For ascending stairs, the lower portion of the gluteus maximus muscle proved to be the main hip extensor during the loading response and mid-stance. The findings also showed that the upper portion of the gluteus maximus muscle functioned more like the gluteus medius muscle than the lower portion of the gluteus maximus muscle during both level and stair walking.     

Hip Muscle Activity during Isometric Contraction of Hip Abduction

[Purpose] This study aimed to determine the effect of varying hip flexion angle on hip muscle activity during isometric contraction in abduction. [Subjects] Twenty-seven healthy men (mean age=21.5 years, SD=1.2) participated in this study. [Methods] Surface electromyography (EMG) was recorded of the upper portion of the gluteus maximus (UGM), lower portion of the gluteus maximus (LGM), tensor fasciae latae (TFL), and gluteus medius (GMed) during isometric contraction under two measurement conditions: hip flexion angle (0, 20, 40, 60, and 80 degrees) and abduction of the hip joint at 20, 40, 60, and 80% maximum strength. Integrated EMG (IEMG) were calculated and normalized to the value of maximum voluntary contraction (MVC). [Results] Results indicated that the IEMG of both the UGM and LGM increased significantly with increases in hip flexion angle, whereas the IEMG of the TFL decreased significantly. The maximum activities of the UGM and the LGM were 85.7 ± 80.8%MVC and 38.2 ± 32.9%MVC at 80 degrees of hip flexion, respectively, and that of the TFL was 71.0 ± 39.0%MVC at 40 degrees of hip flexion. [Conclusion] The IEMG of the GMed did not change with increases in hip flexion angle. Hip flexion angle affected the activity of the GM and TFL during isometric contraction in abduction.Key words: Hip abductor, Electromyography, Muscle activity     

No Difference in Hip Muscle Volumes and Fatty Infiltration in Those With Hip-Related Pain Compared to Controls

BackgroundLittle is known about muscle morphology in people with hip-related pain, without signs of femoro-acetabular impingement syndrome (FAIS). Identifying changes in hip muscle volume, fatty infiltrate and establishing relationships between muscle volume and strength, may provide insight into potential early treatment strategies.PurposesTo: (i) compare the volumes and fatty infiltrate of gluteus maximus, gluteus medius, gluteus minimis, tensor fascia latae and quadratus femoris between symptomatic and less-symptomatic sides of participants with hip-related pain; (ii) compare the volumes and fatty infiltrate of hip muscles between healthy controls and symptomatic participants; and (iii) explore relationships of hip muscle volumes to muscle strength and patient-reported outcome measures in people with hip-related pain.Study DesignCross-sectional studyMethodsMuscle volume and fatty infiltrate (from magnetic resonance imaging), hip muscle strength, patient-reported symptoms, function and quality of life (QOL) were determined for 16 participants with hip-related pain (no clinical signs of FAIS; 37±9 years) and 15 controls (31±9 years). Using One Way Analysis of Co-Variance tests, muscle volume and fatty infiltrate was compared between the symptomatic and less-symptomatic sides in participants with hip-related pain as well as between healthy controls and symptomatic participants. In addition, hip muscle volume was correlated with hip muscle strength, hip-reported symptoms, function and QOL.ResultsNo differences in all the studied muscle volumes or fatty infiltrate were identified between the symptomatic and less-symptomatic hips of people with hip-related pain; or between people with and without hip-related pain. Greater GMED volume on the symptomatic side was associated with less symptoms and better function and QOL (ρ=0.522-0.617) for those with hip-related pain. Larger GMAX volume was associated with greater hip abduction and internal rotation strength, larger GMED volume was associated with greater hip extension strength, and larger QF volume was associated with greater hip abduction strength (rho=0.507-0.638).ConclusionPeople with hip-related pain and no clinical signs of FAIS have hip muscle volumes that are not significantly different than those of matched pain-free controls or their less-symptomatic hip. Larger GMED muscle volume was associated with fewer symptoms and greater strength.Level of evidenceLevel 3a     

Concurrent Validation and Reference Values of Gluteus Medius Clinical Test

ContextThe hip abductor muscles, mainly the gluteus medius, are responsible for controlling hip adduction in a closed kinetic chain. Frontal plane knee alignment, assessed during functional activities such squatting, jumping and running, may overload joint structures, like the anterior cruciate ligament and patellofemoral joint. The hand-held dynamometer is reliable and effective for testing the muscular strength of the hip abductors.Objectives1. To assess the concurrent validity between the gluteus medius clinical test and a maximum isometric force test of the hip abductors using the hand-held dynamometer; (2) to determine the intra and inter-examiner reliability for the application of the gluteus medius clinical test; and (3) to describe reference values of gluteus medius clinical test on a population of youth athletes.DesignCross-sectional.MethodsThirty healthy individuals were recruited for validity and reliability testing. On the first day, participants performed the maximal isometric test of the hip abductors, measured via hand-held dynamometry. On the following week, the gluteus medius clinical test was performed. Intraclass correlation coefficients (ICC_2,2) were computed for the reliability analysis, with a 95% confidence interval. To generate reference values, the gluteus medius clinical test was performed on 273 athletes.ResultsThe results of this study indicated a weak positive correlation (r = 0.436, p = 0.001) between tests, which indicates that they examine different domains of gluteus medius muscle function, likely endurance and muscle strength. The magnitude of computed ICCs (>0.95) indicates excellent intra- and inter-examiner reliability.ConclusionThe findings of the current study indicate that the gluteus medius clinical test is reliable and examines a domain of muscular function not fully captured by HHD. The clinical test developed in this study is low-cost and can be included for gluteus medius assessment.Level of evidenceLevel 3.     

How Different Knee Flexion Angles Influence the Hip Extensor in the Prone Position

[Purpose] The present study examined the effects of knee flexion angle on hip extensor muscle activity. [Subjects and Methods] Twenty healthy subjects maintained knee flexion angles of 0°, 30°, 60°, 90° and 110° in the prone position and performed maximal voluntary contraction in hip extension. Maximum torque in hip extension at the different angles was measured, and surface electromyogram activities of the gluteus maximus (GM), biceps femoris (BF) and semitendinosus (ST) were recorded and normalized by the maximum voluntary isometric contraction (MVIC). [Results] The maximum torque of the hip extensor showed significant decreases between 0°and 60°, 90° and 110° of knee flexion. The muscle activity of BF was significantly high at 0°, and GM showed a significantly higher activity than both BF and ST at 60°, 90°and 110° of knee flexion. [Conclusion] The maximum torque in hip extension and muscle activities of BF and ST were significantly high at 0° but they decreased at knee flexion angles of more than 60°. Therefore, we consider that more than 60° of knee joint flexion is required to increase GM activity, and to reduce the muscle activities of BF and ST.Key words: Gluteus maximus, Hamstring muscle, Prone hip extension     

Effect of abduction and external rotation of the hip joint on muscle onset time during prone hip extension with knee flexion

[Purpose] This study investigated the effect of hip position on muscle onset time during prone hip extension with knee flexion. [Subjects] The study included 21 healthy male volunteers. [Methods] Muscle onset times of the right gluteus maximus, right hamstrings, bilateral lumbar erector spinae, and bilateral lumbar multifidus were measured using surface electromyography during right hip extension with knee flexion in the prone position. Measurements were made with the hip in 3 positions: (1) neutral, (2) abduction, and (3) abduction and external rotation. [Results] Gluteus maximus onset relative to the hamstrings was significantly earlier with hip abduction and with hip abduction and external rotation compared with that with the hip in the neutral position. Gluteus maximus onset relative to the hamstrings was significantly earlier with hip abduction and external rotation compared with that with hip abduction. The bilateral multifidus and left lumbar erector spinae onset times relative to the hamstrings were significantly earlier with hip abduction and external rotation compared with those with hip abduction and with the hip in the neutral position. [Conclusion] Abduction and external rotation of the hip during prone hip extension with knee flexion is effective for advancing the onset times of the gluteus maximus, bilateral multifidus, and contralateral lumbar erector spinae.Key words: Prone hip extension with knee flexion, Hip joint position, Muscle onset time     

Influence of Hip Joint Position on Muscle Activity during Prone Hip Extension with Knee Flexion

[Purpose] This study investigated the selective activation of the gluteus maximus during a prone hip extension with knee flexion exercise, with the hip joint in different positions. [Subjects] The subjects were 21 healthy, male volunteers. [Methods] Activities of the right gluteus maximus, right hamstrings, bilateral lumbar erector spinae, and bilateral lumbar multifidus were measured using surface electromyography during a prone hip extension with knee flexion exercise. Measurements were made with the hip joint in each of 3 positions: (1) a neutral hip joint position, (2) an abduction hip joint position, and (3) an abduction with external rotation hip joint position. [Results] Gluteus maximus activity was significantly higher when the hip was in the abduction with external rotation hip joint position than when it was in the neutral hip joint and abduction hip joint positions. Gluteus maximus activity was also significantly higher in the abduction hip joint position than in the neutral hip joint position. Hamstring activity was significantly lower when the hip was in the abduction with external rotation hip joint position than when it was in the neutral hip joint and abduction hip joint positions. [Conclusion] Abduction and external rotation of the hip during prone hip extension with knee flexion exercise selectively activates the gluteus maximus.Key words: Prone hip extension with knee flexion, Hip joint position, Electromyography