Hip Abductor Muscle Research Articles

The short-term effects of low-load isometric resistance training by the addition of neuromuscular electrical stimulation on the rate of force development in hip abductor muscles

The short-term effects of low-load isometric resistance training by the addition of neuromuscular electrical stimulation on the rate of force development in hip abductor muscles

Posture Stability and Kinematics While Performing a 180° Turning Step in Elderly Individuals With and Without Vertebral Compression Fracture and in Middle-Aged Adults

Older adults with vertebral compression fracture (VCF) have spinal malalignment with large postural sway while standing. The purposes of this study identified the turning strategy of patients with VCF while walking. The study enrolled 18 adults with VCF (VCF group) and 29 older adults (OA group) and 15 middle-aged adults (MA group) without spinal deformity. The Biodex balance system was employed to assess posture stability. An inertia motion system recorded kinematic data during walking. The 180° turning step before sitting was divided into braking, mid-stance, swing, and terminal loading phases for kinematic analysis. Posture stability score showed that the VCF group achieved the lowest stability. The patients with VCF used slower acceleration and less mobility of the head and spine when turning. However, the VCF group had a larger hip abduction range of motion than the OA group; the OA group exhibited larger thoracic rotation than the MA and VCF groups. The VCF group exhibited less gait stability and coordination between the head and thigh on the sagittal plane than the other groups. Additionally, the VCF group had greater head/lower spine acceleration variability on the frontal plane. Kinematic joint modulations were required, depending on the phase of the turn step. The patients with VCF depend more heavily on a hip strategy to maintain gait stability than do other adult groups. To address gait stability and prevent falls for the patients with VCF, a training program should include balance, trunk mobility, and hip abductor muscle strength training.

Effect of femoral offset and limb length discrepancy on hip joint muscle strength and gait trajectory after total hip arthroplasty

BackgroudFemoral offset (FO) and limb length discrepancy (LLD) are important perioperative considerations when performing THA. Decreased FO prevents improvement of gait and muscle recovery and residual LLD has a prominent influence on patient satisfaction with THA, while few studies have investigated the relationship between FO and/or LLD and gait disturbances. We investigated the association between these two factors and hip muscle strength and the results of 3-D gait analysis after THA. MethodsWe evaluated 92 patients (including 20 patients who underwent gait analysis) in whom total hip arthroplasty was performed for unilateral evere osteoarthritis of the hip joint. FO and LLD were measured on a standard anteroposterior radiograph of the pelvis. Hip muscle strength was evaluated by isometric hip flexion (in the manner of straight leg raising test: SLR) and hip abduction strength. To evaluate 3-D walking trajectory, we used a portable gait analyzer. ResultsReduction of global FO by > 5 mm after THA compared to the contralateral hip was associated with hip abductor muscle weakness. On the other hand, LLD ≤ 20 mm had no influence on hip abductor muscle strength and SLR strength. In gait analysis, SLR strength showed a significant difference between the sagittal plane symmetrical and asymmetrical groups. ConclusionPostoperative global FO > 5 mm less than that of the contralateral hip was associated with hip abductor muscle weakness. And, from the results of 3-D gait analysis, SLR weakness may increase gait asymmetry in the sagittal plane.

Hip Abductor Muscle Weakness after Antegrade Nailing of Femoral Fractures

Nailing of femoral fractures is now considered as the standard line of management, although having many advantages, this technique carries some risks related to the technique, in this short review we will handle the issue of hip abductor muscle weakness after antegrade nailing of femoral fractures.

Natural history of late-onset GM2 gangliosidosis: Four years of data collected at NTSAD annual conferences

Intramuscular fat infiltration is a dynamic process, in response to exercise and muscle health, which can be quantified by estimating fat fraction (FF) from Dixon MRI. Healthy hip abductor muscles are a good indicator of a healthy hip and an active lifestyle as they have a fundamental role in walking. The automated measurement of the abductors' FF requires the challenging task of segmenting them. We aimed to design, develop and evaluate a multi-atlas based method for automated measurement of fat fraction in the main hip abductor muscles: gluteus maximus (GMAX), gluteus medius (GMED), gluteus minimus (GMIN) and tensor fasciae latae (TFL).We collected and manually segmented Dixon MR images of 10 healthy individuals and 7 patients who underwent MRI for hip problems. Twelve of them were selected to build an atlas library used to implement the automated multi-atlas segmentation method. We compared the FF in the hip abductor muscles for the automated and manual segmentations for both healthy and patients groups. Measures of average and spread were reported for FF for both methods. We used the root mean square error (RMSE) to quantify the method accuracy. A linear regression model was used to explain the relationship between FF for automated and manual segmentations.The automated median (IQR) FF was 20.0(16.0–26.4) %, 14.3(10.9–16.5) %, 15.5(13.9–18.6) % and 16.2(13.5–25.6) % for GMAX, GMED, GMIN and TFL respectively, with a FF RMSE of 1.6%, 0.8%, 2.1%, 2.7%. A strong linear correlation (R2 = 0.93, p < .001, m = 0.99) was found between the FF from automated and manual segmentations. The mean FF was higher in patients than in healthy subjects.The automated measurement of FF of hip abductor muscles from Dixon MRI had good agreement with FF measurements from manually segmented images. The method was accurate for both healthy and patients groups.

Hip abductor muscle weakness and slowed turning motion in people with knee osteoarthritis

Laser range sensor-based timed up and go (laser-TUG) test can evaluate performance in TUG subtasks (sit-to-walk [STW], walking a short distance, and turning). This study aimed to test the hypothesis that weaker hip abductor muscle strength is more significantly associated with slowed turning speed than with the other TUG subtasks (STW and straight walking) after controlling for quadriceps muscle strength in patients with knee osteoarthritis (OA). Community-dwelling participants with knee OA (Kellgren and Lawrence [K&L] grade ≥ 1; mean age, 68.6 years; 70.3% women) underwent laser-TUG. Spatiotemporal gait parameters in TUG and the TUG subtasks were evaluated as outcome measures. The isometric muscle strength of the hip abductor and quadriceps was measured using a hand-held dynamometer. Multiple linear regression analysis was performed to examine the relationship between muscle strength as an independent variable and spatiotemporal parameters as dependent variables. The relative importance of hip abductor muscle strength was determined using the percentages of unique variance. Participants with weaker hip abductor muscle strength demonstrated 0.094 m/s slower turning speed after adjustment for covariates including quadriceps muscle strength. The unique variance explained by hip abductor muscle strength in turning speed was 2.1%. However, no significant relationships were confirmed between weak hip abductor muscle strength and the time to perform TUG and the straight walking (forward and return) phase. These findings indicate that turning motion may be more sensitive to aggravated hip abductor muscle weakness and may show better response to hip muscle strengthening exercises. Longitudinal studies are warranted to elucidate this issue.

Hip Adduction and Abduction Torque-angle Curve Characterization of Speed Skating Athletes.

Speed skating is a cyclic sport which involves the hip abductor muscles, impelling the participant forwards, and adductor muscles, in the recovery phase and decelerating the abduction movement eccentrically. This paper has the objective of describing and comparing the abduction/adduction torque-angle curves of speed skating athletes (N=10) with a group of non-practitioners young participants (N=10). Both groups presented similar peak torques and electromyography patterns for tensor fascia lata, gluteus medius, long adductor and adductor magnus. However, athletes showed higher torque-angle curve integral and abduction and adduction peak torques at different hip angles than the control group. These findings suggest an adaptation of their musculotendon actuators and a better capacity to generate mechanical work and power during a propulsion-recovery cycle.

Effects of a Community-Based Tai Chi Program on Balance, Functional Outcomes, and Sensorimotor Function in Older Adults

Aims: Examine effects of a community Tai Chi program on measures of balance and sensorimotor function.Methods: In a pretest and post-test design, balance was measured in older adults (N = 344; 73.4 ± 7.4 years) with 30-s chair stand, timed-up-and-go, and 4-stage balance test following a 12-week community-based Tai Chi intervention. Balance and sensorimotor measures, including hip abductor electromechanical delay and hip proprioception, were measured in a smaller sample of older adults (n = 11; 67.3 ± 3.7 years).Results: Balance improved (p < 0.0001) following intervention compared to pretest. Similarly, participants in the smaller sample showed improvements at post-test (p < 0.05) in electromechanical delay and lower extremity proprioception, but no bone density or muscle mass changes.Conclusions: These preliminary results suggest that a community-based Tai Chi program improves balance in older adults. In a smaller sample, Tai Chi resulted in additional sensorimotor changes, specifically faster hip abductor muscle contraction speed and improved hip proprioception.

Magnetic Resonance Imaging Assessment of Hip Abductor after Total Hip Arthroplasty Using a Direct Lateral Approach.

Surgical techniques and rehabilitations after total hip arthroplasty (THA) play a significant role in the improvement of pain and limping. This study aimed to assess hip abductor muscle's diameter and its strength after 6 months postoperative THA performed by Hardinge approach. After obtaining the patients' demographic characteristics, the preoperative values of patients' hip abductor muscle diameter were measured using magnetic resonance imaging, and were compared with postoperative values 6 months later. Moreover, the hip abductor muscle's strength was assessed using the Trendelenburg test. A total of 88 patients participated in this study with a mean age of 47.3±1.574 years. It should be noted that 55.7% of the participants were male. Muscle diameter decreased from a mean value of 27.07±7.485 preoperative to mean value of 25.64±7.353 mm postoperative (P<0.001). Moreover, the degrees of Trendelenburg test (i.e., mild or severe) decreased after surgery (P<0.001). There was no significant difference between the frequencies of different grades of limping according to the studied variables. A decrease was observed in gluteus medius muscle diameter, and the Trendelenburg test results were improved in this study. Moreover, the difference between pre- and postoperative gluteus medius muscle diameters were measured using MRI. It can be concluded that MRI is not an appropriate diagnostic tool for the assessment of abductor strength after THA in the 6-month postoperative visit. Accordingly, it is suggested to evaluate muscle strength before and after each surgery to schedule the following treatment protocol required for each patient.

Hip Abductor Muscles Strengthening's Effect on Lower Extremity's Function of Runners With Illitotibial Syndrome

Introduction: Iliotibial Band Syndrome (ITBS) is among the most common injuries in distance runners. Thus, the present study investigated the effect of a special strengthening exercise program for abductor’s muscles according to NSCA protocol, on pain reduction and lower extremity function improvement among elite distance runners with ITBS. Materials and Methods: The subjects of the present study were 32 elite distance runners who were randomly divided into two groups of control and experimental (n=16/group). The experimental group performed the exercise program for 8 weeks; however, the control group followed their routine program. The pain was assessed by the Visual Analogue Scale of pain (VAS) and the lower extremity function was assessed by the Lower Extremity Functional Scale (LEFS). In the statistical procedure, the repeated-measures Analysis of Variance (ANOVA) and Bonferroni test was applied to determine the within-group and between-groups differences of the study variables, and for assessing the stability level of protocols’ effect on the experimental group and comparing the stages, respectively. The significance level was considered 0.05, test power as 95%, and effect size as 0.7; SPSS was used for all data analyses. Results: The present study data indicated that the strengthening exercise program on hip abductor muscles caused a significant decrease in pain (P=0.0001). The lower extremity function manifested a significant improvement in the experimental group after 8 weeks of strengthening exercise protocol (P=0.0001); it was durable even 3 months after the end of the exercise program. Conclusion: Hip abductor muscle strengthening, based on NSCA protocol, can be an effective approach in reducing pain and improving lower extremity function in elite distance runners with ITBS.

Gait Training Using a Wearable Robotic Device for Non-Traumatic Spinal Cord Injury: A Case Report

Introduction:We aimed to report the clinical evaluation results of gait training with the Honda Walking Assist Device® (HWAT) in a patient with spinal cord injury (SCI).Patients and Methods:A 63-year-old male with SCI (grade D on the American Spinal Injury Association Impairment Scale) underwent 20 HWAT sessions over 4 weeks. The self-selected walking speed (SWS), mean step length, cadence, 6-minute walking test (6MWT), Walking Index for SCI score, SCI Functional Ambulation Inventory gait score, American Spinal Injury Association Impairment Scale grade, neurological level, upper and lower extremity motor scores, modified Ashworth Scale, Penn Spasm Frequency Scale, and Spinal Cord Independence Measure version III were measured on admission, at the start of HWAT, at 2 and 4 weeks post-HWAT, and at discharge. Three-dimensional kinematic gait analysis and electromyographic assessments were performed before and after HWAT.Results:The patient safely completed 20 HWAT sessions. We found improvements above the clinically meaningful difference in SWS and 6MWT as well as increased hip extension, ankle plantar- and dorsi-flexion range of motion and increased hip extensor, abductor, adductor, and ankle plantar flexor muscle activity.Discussion:The SWS improved more markedly during the HWAT intervention, exceeding the minimal clinically important difference (0.10 to 0.15 m/s) in walking speed for people with SCI until discharge. Moreover, the 6MWT results at 2 weeks after the start of HWAT exceeded the cutoff value (472.5 m) for community ambulation and remained at a similar value at discharge.Conclusion:The walking distance (6MWT) and the walking speed (SWS) both demonstrated clinically important improvements following 20 treatment sessions which included HWAT.

Core Stability and Hip Exercises Improve Physical Function and Activity in Patients with Non-Specific Low Back Pain: A Randomized Controlled Trial

Approximately 90% of low back pain (LBP) diagnoses are non-specific (NSLBP; i.e. with unknown cause). In NSLBP patients, the hamstrings, iliopsoas, piriformis, and tensor fasciae latae are overactive due to weak hip abductor, extensor, and core muscles. Core stability is essential for proper load balance within the pelvis, spine, and kinetic chain, and core stability exercise (CSE) is an exercise treatment regimen for LBP conditions. We investigated how core stability and hip muscle stretching exercises affected NSLBP patients' physical function and activity. Patients were randomly allocated to three groups. The Stretch group (n = 24) performed exercises for hip muscle stretching for maximal motion; the Strengthen group (n = 22) performed exercises for hip muscle strengthening while maintaining the maximal isometric contraction. The Sham group (n = 20) received gentle palpation of the skin. Therapy was conducted thrice weekly for 6 weeks. Pain intensity, lower back instability, and hip muscle flexibility were measured to assess physical function. Disability level, balance ability, and quality of life were measured to assess physical activity. Data were collected prior to intervention and at 6-week follow-up. There were significant within-group changes for all measurements (P < 0.05). The Stretch and Strengthen groups had greater improvements in pain intensity, disability level, balance ability, and quality of life than the Sham group. Lower back instability and hip muscle flexibility had the greatest improvement in the Stretch group. In conclusion, CSE and hip muscle stretching are effective at improving physical function and activity in NSLBP patients.

Abductor Deficiency-Induced Recurrent Instability After Total Hip Arthroplasty.

» Operative intervention for deficient hip abductor muscles may require muscle transfer or the use of synthetic materials, possibly with biologic augmentation, to help stabilize the hip joint and prevent further dislocation following total hip arthroplasty (THA). » Direct repair of the abductor mechanism onto the greater trochanter can be used in patients who present with instability <15 months following primary THA. » Augmentation of soft tissue with acellular dermal allografts can be considered for patients with abductor avulsion that requires posterior capsular reconstruction. » The Achilles tendon + calcaneal bone allograft is indicated for patients who have undergone multiple prior revision surgeries, who have experienced failure of nonoperative management, and have tissue inadequacy in the posterior wall of the hip joint. » The gluteus maximus tendon transfer is indicated in patients with chronic abductor tears, limited or loss of function in the gluteus medius and minimus, and a fully functioning gluteus maximus. » Vastus lateralis transfer may benefit patients with a history of multiple revision procedures, large separation between the gluteus medius tendon and the proximal part of the femur, and the ability to observe the postoperative protocol of splinting for 6 weeks. » The latissimus dorsi tendon transfer should be reserved as a reconstructive procedure for patients with acute abductor insufficiency, such as those who have undergone extensive tumor resection. » Synthetic mesh can be used to enable capsular reconstruction and prosthesis stabilization in patients undergoing salvage procedures for tumors of the hip and associated soft tissues. » Synthetic ligament prostheses can be used in patients with recurrent posterior dislocations in the setting of normal components. » The fascia lata plasty is indicated for patients with recurrent posterior instability without an identifiable cause. » Although the quality of literature is limited, surgical interventions utilizing techniques of soft-tissue augmentation have shown promising outcomes with regard to pain relief, limping, ambulation, and the reduction of instability following THA.

Comparison of muscle activity, strength, and balance, before and after a 6-month training using the FIFA11+ program (part 2).

Sports injury prevention training programs have been reported to be effective in decreasing the incidence of injuries. The aim of this study was to evaluate the effects of a 6-month training period, using part 2 of the FIFA11+ program (the Fédération Internationale de Football), on the activation and strength of core and lower limb muscles and on static and dynamic balance performance. Case series; level of evidence, 4. Eight college male soccer players, aged mean 20.4 ± 0.5 years old, completed the FIFA11+ program at least three times per week for 6 months. The following variables were measured both before and after the 6-month training program: activities of more than 30 muscles (core and lower limb muscles), measured using the standardized uptake values of 18F-fluorodeoxyglucose on positron emission tomography; isokinetic strength of the knee flexor and extensor and hip abductor muscles, measured at 60° s-1; static balance over a 60-s period, measured using a gravicorder; and dynamic balance, measured using the star excursion balance test. Training improved the activity levels of core (obliquus externus abdominis and erector spinae) and lower limb (tibialis anterior) muscles (p ≤ 0.03), corrected the between-limb difference in the activation of the semimembranosus and improved dynamic balance, with a greater training effect on the nondominant limb (p ≤ 0.02). Training also improved the knee flexor force of the nondominant lower limb (p = 0.02). Routine performance of the FIFA11+ program can improve the activation of core and lower limb muscles, with a concomitant improvement in dynamic balance. These improvements could be beneficial in lowering the risk of sports-related injuries.

Fatigue matters: An intense 10 km run alters frontal and transverse plane joint kinematics in competitive and recreational adult runners

BackgroundFatigue is an essential component of distance running. Still, little is known about the effects of running induced fatigue on three-dimensional lower extremity joint movement, in particular in the frontal and transverse planes of motion. Research questionHow are non-sagittal plane lower extremity joint kinematics of runners altered during a 10 km treadmill run with near-maximum effort? MethodsIn a cross-sectional study design, we captured three-dimensional kinematics and kinetics at regular intervals throughout a 10 km treadmill run in 24 male participants (subdivided into a competitive and recreational runner group) at a speed corresponding to 105 % of their season-best time. We calculated average and peak joint angles at the hip, knee and ankle during the stance phase. ResultsWe observed peak deviations of 3.5°, 3° and 5° for the hip (more adduction), knee (more abduction) and ankle (more eversion) in the frontal plane when comparing the final (10 km) with the first (0 km) measurement. At the end of the run peak knee internal rotation angles increased significantly (up to 3° difference). Running with a more abducted knee joint and with a higher demand for hip abductor muscles in the unfatigued state was related to greater fatigue-induced changes of joint kinematics at the knee and hip. SignificanceThe fatigue related change of non-sagittal joint kinematics needs to be considered when addressing risk factors for running-related injuries, when designing shoe interventions as well as strengthening and gait retraining protocols for runners. We speculate that strengthening ankle invertors and hip abductors and monitoring the dynamic leg axis during running appear to be promising in preventing fatigue induced alterations of non-sagittal joint kinematics.

Effects of ultrasound-guided percutaneous neuromodulation on the activation of hip abductors in a professional tennis player: a single case study

Abstract Background Ultrasound-guided percutaneous neuromodulation (US-guided PNM) is defined as electric stimulation of a peripheral nerve at some point of its trajectory via a needle, with analgesic objectives and for the improvement of muscle function. Hip abductor muscles play an important role in the performance of tennis players, participating primarily in the transfer of forces in situations such as stopping and starting, changes in direction and even hitting the ball. Aims The aims of this study were to confirm the effects of US-guided PNM on the superior gluteal nerve on strength and muscle activity in hip abductors and the reduction of the Q angle of the knee during a single-legged squat in a high performance athlete. Material and Methods The subject was a high performance athlete aged 17, without traumatic injuries to the lower limb. The study was conducted in the installations of AY360° Salud y Deporte. The following variables were measured before and after the intervention: force (MVIC), muscle activity (RMS) using surface electromyography and the knee Q angle during a single-legged squat using Kinovea video analysis. A treatment protocol was performed under ultrasound guidance using a PES current with 6 Hz pulses and a pulse duration of 250 μs. In total, 5 applications of 15 seconds' duration were applied with the help of a pointer. Results Improvements were obtained for strength measurements, from a MVIC of 0.13 mV (50.72%) to 0.26 mV (100%), for muscle activity RMS improved from 13.26% to 23.96%, and degrees changed from 23.6° to 21°. Conclusions The US-guided PNM technique, according to the parameters studied, appears to be a useful tool for the improvement of the cited variables.

Modulation of the rate of force development in hip abductor muscles by neuromuscular electrical stimulation during gait

Purpose/aim of the study: An increase of hip abductor muscle strength contributes to the increase in gait speed. It is known that the rate of force development (RFD), an indicator of muscle strength, is increased by the combined use of low-intensity neuromuscular electrical stimulation (NMES) to the glutaeus medius (GM) and low-load resistance training (RT). However, it is unclear whether low-intensity neuromuscular electrical stimulation of the glutaeus medius during walking also increases the rate of force development. The aim of this study was to clarify whether NMES to the GM during gait modulates the RFD of the hip abductor muscles in healthy adults.Materials and methods: Twenty-two healthy adults randomly received both gait with sub-motor threshold NMES and gait with sham NMES conditions. The RFD was assessed at pre- and post-intervention. A two-way repeated measures analysis of variance was used to analyse the effects of time and intervention.Results: Gait with sub-motor threshold NMES condition significantly increased the RFD in shorter time interval (0–50 and 0–100 ms) compared to gait with sham NMES condition.Conclusions: These findings suggest that the adding low-intensity NMES of the GM to gait is effective in increasing the RFD of the hip abductor muscles.

Excessive Lateral Trunk Lean in Patients With Cerebral Palsy: Is It Based on a Kinematic Compensatory Mechanism?

Introduction: Excessive lateral trunk lean is a commonly observed gait deviation in children with cerebral palsy (CP), with implications for energy expenditure and the development of back pain. While the trunk lean toward the stance leg is widely interpreted as a compensatory strategy to unload the hip, in CP the relation to hip abductor muscle strength is only weak. Therefore, other mechanisms may play a role in the prevalence of excessive trunk lean in CP, or it could be a primary motor function deficit.Research Question: Is the excessive lateral trunk lean in patients with CP part of an underlying biomechanical mechanism?Materials and Methods: Patients with bilateral CP (N = 255; age 13.6 ± 6.6 years) were retrospectively included and divided into a group with (n = 174) and without (n = 81) excessive lateral trunk lean. Ten lower-extremity joint angle waveforms were analyzed using a principal component analysis (PCA) to identify patterns of correlated deviations from average angle waveforms. Binary logistic regressions were performed to determine the discriminative capacity of the identified patterns.Results: The PCA identified correlated kinematic patterns, with lower-order patterns showing more common gait pathologies, such as torsional malalignments and crouch gait pattern. Within five patterns, significant (p < 0.0025) group differences were identified. Interestingly, the trunk lean was not always distinctive in these patterns and despite the significant differences their effect sizes were small. The logistic regression was unable to reliably classify patients based on their trunk lean patterns.Discussion: The current study identified multiple trunk lean-related patterns, however, excessive trunk lean was not attributable to a distinctive CP related gait pathology or to a specific compensatory strategy. Overall, the results do not support the hypothesis that excessive trunk lean is part of a biomechanical mechanism. Therefore, it seems more likely that excessive lateral trunk lean is based on other disease specific dysfunctions, influenced by the severity of the disease.

Periacetabular osteotomy using an imageless computer-assisted navigation system: a new surgical technique.

Periacetabular osteotomy (PAO) is an effective surgical treatment for hip dysplasia. The goal of PAO is to reorient the acetabulum to improve joint stability, lessen contact stresses and slow the development of hip arthrosis. During PAO, the acetabulum is repositioned to adequately cover the femoral head. PAO preserves the weight-bearing posterior column of the pelvis, maintains the acetabular blood supply and retains the hip abductor musculature. The surgical technique needed to perform PAO is technically demanding, with correct repositioning of the acetabulum the most important—and challenging—aspect of the procedure. Imageless navigation has proven useful in other technically challenging surgeries, although its use in PAO has not yet been investigated. We have modified the standard technique for PAO to include the use of an imageless navigation system to confirm acetabular fragment position following osteotomy. Here, we describe the surgical technique and discuss the potential of this modified technique to improve patient-related outcomes.

Effects of Hip Abductor Muscles Exercises on Pain and Function in Patients With Patellofemoral Pain: A Systematic Review and Meta-Analysis.

Rogan, S, Haehni, M, Luijckx, E, Dealer, J, Reuteler, S, and Taeymans, J. Effects of hip abductor muscles exercises on pain and function in patients with patellofemoral pain: A systematic review and meta-analysis. J Strength Cond Res 33(11): 3174-3187, 2019-This systematic review and meta-analysis considered the effects of hip strengthening (i.e., abductor and external rotator muscles) vs. no hip strengthening on pain and of hip strengthening combined with knee strengthening vs. knee strengthening (i.e., quadriceps muscles) alone on pain and functional status in patients with patellofemoral pain (PFP). Eleven, randomized, controlled trial (RCT) studies and 1 non-RCT study were included, totaling 604 participants. Female athletes were included in one study, whereas untrained participants were included in the other studies. On average, the studies showed a low methodological quality. Hip muscle strengthening showed greater pain-reducing effects when compared with no hip strengthening (standardized mean difference [SMD] = -1.91; 95% confidence interval [CI], -2.92 to -0.9; p = 0.0002). When comparing a combined hip and knee muscle strengthening with knee muscle strengthening alone, pain was reduced in the combined hip and knee-strengthening group (SMD -0.99; 95% CI, -1.99 to 0.02; p = 0.05), whereas function showed a SMD of 0.70 (95% CI, 0.25-1.14; p = 0.002) again favoring the combined hip and knee-strengthening group. This meta-analysis showed evidence that the strengthening of the hip abductor muscles can reduce pain and function in patients with PFP. Because studies including highly trained patients with PFP are currently lacking, one should be careful when applying the clinical findings of this meta-analysis when working with athletes. Trial registration: PROSPERO 2014:CRD42014010716.