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Relationship Between Hip and Core Strength and Frontal Plane Alignment During a Single Leg Squat
Abstract
Objective
The purpose of this study was to examine the relationship between frontal plane kinematics of the single leg squat and strength of the trunk and hip in females.
Participants
Forty healthy females participated in this study.
Methods
An isometric “make” test using a dynamometer was used to assess peak force normalized to body weight for hip abduction, hip extension, hip external rotation, and a sidelying plank test. Two-dimensional software was used to analyze the frontal plane projection angle (FPPA) and pelvic angle during a single leg squat to 60°.
Results
All 4 strength factors were significantly correlated with the FPPA, ranging from r=0.396 to r=0.466. During multiple regression analysis, hip abduction strength was the greatest predictor of the variation in FPPA at r2=0.22, p =0.002. Thus, hip abduction strength accounted for 22% of the variation in the FPPA during the single leg squat. The only strength factor demonstrating a significant correlation with the pelvic angle was hip extension strength (r=0.550, p<0.001).
Conclusion
Clinicians should consider the role of the hip abductors, hip external rotators, hip extensors and core musculature on the impact on the FPPA during a single squat, with focus on the hip abductors.
... 1 The normal range of DKV of a singleleg landing task has been reported as 1-9 degrees for males and 5-12 degrees for females when measured from a digital video camera two-dimensionally. 2 Anatomical characteristics contribute to DKV, with the Q-angle being the most significant. [3][4][5] Q-angles are measured with similar, although different anatomical landmarks than knee valgus. DKV and static knee valgus are measured from the Anterior Superior Iliac Spine (ASIS) to the mid-patella to a line along the tibia between the medial and lateral malleoli. ...
... However, these studies have not considered the static bony anatomy of the subjects, overlooking the possible contributions of anatomical characteristics. [3][4][5] In parallel, bony anatomy of static knee valgus was found to have a significant relationship with DKV during a drop-jump, while foot alignment, hamstring strength, quadriceps strength, and hip abductor strength had no association. 3 Furthermore, anatomical measurements in both the frontal and transverse planes at the hips and knees have been shown to have an association with DKV during double-leg landing, further adding value to the idea that anatomical differences contribute to dynamic measures. ...
... 14 Moreover, there is conflicting evidence on the relationship between DKV and jump performance. 5,[15][16][17] Confounding variables such as specific training effects and bony anatomy was not considered with these reports. There is also dispute regarding the neuromuscular contributions to DKV, specifically, the association of hip abductor muscle weakness to DKV. 5,[18][19][20][21][22] Finally, interventional studies for improving DKV have had mixed results, with some studies demonstrating improved DKV with training proximally at the hip and core, while others found no change. ...
Background
Dynamic knee valgus (DKV) is widely considered a risk factor for injuries, despite contradictory research. Consequently, athletic performance and injury rehabilitation cueing has primarily focused on keeping the “knees out”.
Purpose
The purpose of this study was to assess jump performance measures and anatomical contributions.
Study Design
Cross-Sectional Study
Methods
Jump height, ground contact time, reactive strength index, and DKV was collected with the MyJump2 and Coach My Video apps. Static anatomical measurements were collected. Subjects completed nine jumps with each leg using the same set-up; performing three single leg six-inch depth jumps with their natural form, three depth jumps with external cuing towards increased DKV, and three depth jumps with cuing towards no DKV. ANOVA was used to compare jump data. Pearson Correlation Coefficients were used to assess relationships between DKV and anatomical measurements, jump height, ground contact time, and reactive strength index. Intraclass correlation coefficient (ICC) was used to assess inter-rater reliability of MyJump2 and Coach My Video measurements.
Results
50 subjects (35 included) participated in this study. With a cued DKV jump, ground contact time had a moderate positive correlation with DKV measurements (r=.49, p<0.01), however, this was not the case with subjects’ natural jump and cued no DKV alignment jumps. Static anatomical measurements of static knee valgus and Q-angle had a weak positive correlation with DKV measurements for subjects’ natural jumps (r=.37, p<0.01 and r=.34, p=0.04, respectively). When DKV measurements were normalized to an anatomical measurement, no correlations existed with any of the performance measurements. There was very strong inter-rater reliability (ICC=.96-.99) of all the measurements.
Conclusion
Bony anatomical alignment should be considered alongside kinematics, as normalization controlled for the differences in DKV. Future research should normalize DKV measurements by bony anatomy when addressing DKV and jump performance.
Level of Evidence
2c
... Repetitions in which the subject lost their balance, moved the base of support, or used the arms to regain balance were not counted. For analysis, we use only the third repetition [20] The images were obtained using a 12 Megapixel digital camera (Smartphone model Samsung Galaxy s10e), with a sampling rate of 60 Hz, positioned 1.5 m away from the participant at the height of one meter from the ground. The absolute angle of hip adduction (ADD) was obtained by calculating the angle formed between the lines from the markers on the knee and the ipsilateral ASIS and the line between the two ASIS markers (Fig. 1, letter A). ...
... Many studies have observed that the strength and endurance of the trunk lateral flexors' muscles seem to influence lower limb alignment [20,33,34]. Specifically, ipsilateral contraction of these muscles produces lateral trunk flexion, which can prevent excessive contralateral pelvic drop [14], which is an action associated with excessive DKV [24]. ...
... This study has some limitations: (i) the use of 2D kinematic measurement that, although commonly used in the literature and presenting reasonable values of agreement with the 3D measurements [44], neglects changes in the transverse plane [7]; (ii) despite the FSD test being inexpensive and possible to administer with minimal training in a variety of settings, it may be a test that presents little challenge to the lower limb alignment of highly trained individuals, such as CF athletes, which may have contributed to the results [10]; (iii) the non-questioning of the reasons for interruption of the side plank test, which could help in the interpretation of the observed results since shoulder fatigue can occur before the trunk's [39]; (iv) although mechanical aspects of the trunk and ankle can contribute to lower limb alignment, there is an important contribution of hip muscles that was not measured in our study [5,20]. Finally, we measured only the hip and knee, and future studies should investigate whether the trunk and ankle parameters are associated with individual components of the DKV (trunk lean, hip rotation, and tibial rotation), which can be measured with 3D motion capture [24]. ...
PurposeCrossFit® (CF) is a high-intensity training method with a large number of practitioners, having an injury prevalence similar to other sports. Although excessive dynamic knee valgus is related to several injuries and associated with the trunk muscles’ endurance and dorsiflexion range of motion (DF-ROM), no study has evaluated these parameters in CF practitioners. The aim of the study was to investigate the association between lower limb alignment during the step-down test, DF-ROM and lateral trunk muscle endurance in CrossFit® (CF) practitioners.Methods
Forty-two CF practitioners performed the following tests on both limbs: (i) DF-ROM with the weight-bearing lunge test; (ii) knee frontal plane projection angle (FPPA) and hip adduction (hip ADD) ankle during the forward step-down test; (iii) trunk lateral flexors’ endurance with the side plank test.ResultsNo significant associations were found between knee FPPA and DF-ROM in both limbs (preferred: r = 0.192; p = 0.230; non-preferred: r = 0.089; p = 0.581) or side plank time (preferred: r = 0.086; p = 0.594; non-preferred: r = 0.248; p = 0.117). Moreover, no significant associations were found between hip ADD and DF-ROM in both limbs (preferred: r = 0.005; p = 0.975; non-preferred: r = 0.175; p = 0.275) or side plank time (preferred: r = – 0.134; p = 0.403; non-preferred: r = 0. 171; p = 0.284).Conclusion
Lateral trunk flexors’ endurance and ankle dorsiflexion range of motion are not associated with hip and knee kinematics during the forward step-down test in CrossFit®.
... From the database search, a total of 1059 papers were found (Fig. 1). Upon screening, only seven papers met the inclusion criteria [2,6,[9][10][11][12][13]. Additional six papers were included following a manual search [14][15][16][17][18][19]). Therefore, 13 studies involving 733 participants (female = 587; male = 146; patients = 69; healthy adults = 664) were included in the review. ...
... From the 13 included studies, only one study did not find correlation between knee valgus and hip strength (dominant leg: p =0.085, non-dominant leg: p =0.581, N =279), probably because the study involved elite female soccer players [15]. The other 12 included studies [2,6,[9][10][11][12][13][14][16][17][18][19]) found association between peak knee valgus and hip strength (r = 0.336-0.83; p <0.05) in various dynamic tasks (Table 1). ...
... In studies that used a handheld dynamometer to measure hip strength, Soares et al. [10], Malloy et al. [12], Thijs et al. [19], Baldon et al. [17], and Hollman et al. [13] showed significant correlations across hip strength and knee angle while Nilstad et al. [15], did not observe any significant correlation. In studies that assessed hip strength isometrically, Stickler et al. [11], Norcross et al. [18] and McCurdy et al. [16] showed significant correlations among hip strength and knee angle. According to Stickler et al. [11] the strength of hip abductors was the top predictor of the knee frontal plane projection angle (FPPA) during single leg squat (SLS). ...
Background
Previous systematic reviews regarding the association among hip strength and dynamic knee valgus were limited to asymptomatic female adults.AimsThe focus of the current systematic review was to examine the association between hip muscle strength and knee kinematics while performing dynamic tasks across male and female adults, with and without knee pain.Methods
Four databases (Scopus, SAGE, Science Direct, and Pubmed) were searched from inception to December 2020. The review included studies that examined the association between hip muscle strength and knee kinematics during various tasks in male and female healthy adults or patients.ResultsA total of 733 participants (female = 587; male = 146; patients = 69; healthy = 664) from 13 studies met the inclusion criteria. Twelve studies found an association between peak knee valgus and reduced hip strength, indicated that increased hip strength would minimize knee valgus in various dynamic tasks. Only one study that involved elite female soccer players showed no correlation between knee valgus and hip strength.Conclusions
The association between hip strength and knee valgus is influenced by the tasks demand, pain, gender, and fitness level of the participants. The review showed that hip strength has substantial role in dynamic knee valgus modulation during functional activities. Coaches and athletes may focus on hip muscle strengthening to reduce the risks of non-contact injuries associated with excessive dynamic knee valgus.The protocol of this review has been registered on 5th December 2020 at PROSPERO with registration number: CRD42020219135.
... The dominant leg was determined by observing which leg the participants used to kick a ball. 20 The preferred stabilizing leg was the non-dominant limb. 21 For the within-day reliability test, the SLS protocol was repeated twice a day with at least a four-hour gap between the trials. ...
... To capture frontal and sagittal motions during the SLS test, two digital cameras (SONY HDR-CX240, Japan) were set approximately 2.4 m in front and to the side of the participants, oriented roughly to the level of the pelvis. 20 Next, the participants were asked to demonstrate double leg squat while the researcher set the angle of knee flexion (60° and 45°) with a goniometer. A clear plastic goniometer was used to determine the desired angle. ...
... During the double limb squat, an adjustable plinth was placed at the height of the ischial tuberosity to indicate the required squat depth (60° and 45° of knee flexion). 20 After that, the participants stood barefoot for ten seconds to have their static standing pose captured. The trials started with the dominant leg as the stance leg for both squat depths. ...
# Background
The single leg squat (SLS) motion imitates various maneuvers in sports. It is commonly used as a functional test for the lower limb. SLS with two-dimensional (2-D) video analysis is regularly performed in the clinical setting to assess dynamic knee valgus (DKV). However, 2-D video analysis may not be able to demonstrate the same level of accuracy as three-dimensional (3-D) motion analysis.
# Purpose
This study aimed to determine the within- and between-day reliability as well as the concurrent validity of 2-D and 3-D motion analysis of lower limb kinematics during 45° and 60° SLS among physically active females with and without DKV.
# Study Design
Cross-sectional study
# Methods
A total of 34 physically active females (17 individuals with excessive DKV and 17 without DKV) participated in the study. Their DKV was determined based on the cut-off values of knee frontal plane projection angle during drop landing. Their lower limb kinematics during SLS at 45° and 60° knee flexion were captured simultaneously by digital cameras (2-D motion capture) and infrared cameras (3-D motion capture). Intraclass Correlation Coefficient (ICC) was used as an indicator for within- and between-day reliability tests of both groups. Bland-Altman Plot and Pearson correlation were used to examine the validity of 2-D and 3-D motion capture methods in evaluating knee valgus angle.
# Results
Two-dimensional knee FPPA and 3-D knee angle measured during 45° and 60° SLS in normal and excessive DKV groups showed moderate to excellent within-day and between-day reliability (ICC≥ 0.50). The current study showed that the 2-D knee frontal plane projection angle (FPPA) during 45° SLS were valid for the non-dominant leg in both groups. Additionally, the 2-D knee FPPA during 60° SLS were valid for non-dominant leg in excessive DKV group and dominant leg in normal group.
# Conclusion
Two-dimensional knee FPPA during 45° and 60° SLS also showed high within-and between-day reliability for both groups. The validity of 2-D knee FPPA during SLS depends on the squat depth, stance leg, and presence of DKV.
# Level of Evidence
2B
... While providing support through the sagittal plane is a leap forward in exoskeleton technology, balancing in 3D space dictates the presence of active joints that enable the CoM (Center of Mass) to sway along the coronal plane. The studies in both healthy and impaired human biomechanics have pointed out the importance of hip abductors for stable gait generation [16], [17]. In a simulation study, it was observed that human gait is quite sensitive to hip abductors [18], and any fatigue related to this joint may affect the whole leg kinematics [19]. ...
... On the other side, exoskeletons with fully-actuated legs, e.g., Atalante [11], can address hands-free walking aid; yet there could be an optimal compromise between these two specimens. Considering the robust stabilizers [22]- [25], we argue that self-stabilization could be attained with exoskeletons that possess 4 active joints per leg, covering the fundamental aspects of walking, i.e., complete support through hip A/A and F/E, knee F/E, and ankle D/PF [15], [16], [18], [20], [26]. Compared to fully actuated systems, decreasing the total number of active joints from 12 to 8 enables us to improve power requirement and energy autonomy while reducing the hardware complexity and total mass. ...
This article presents the design, development, and implementation of walking control for the bipedal exoskeleton prototype Co-Ex. The main objective in developing this prototype is to take a successive step towards ambulatory support via an exoskeleton with self-stabilization capability. To attain this goal, Co-Ex is equipped with 8 torque-controllable active joints to provide ambulatory support while ensuring improved environmental interaction. The development of Co-Ex led to three contributions: i) self-stabilization capability in 3D against external disturbances, ii) a locomotion control framework that provides dynamically balanced walking behavior in 3D despite the underactuated leg configuration, iii) a power-aware leg design in which most actuators are deployed around the waist for reduced leg inertia. To verify the self-stabilization and locomotion capabilities of Co-Ex, we conducted a series of experiments using a dummy manikin. As a result, Co-Ex showed self-stabilization behavior against disturbances and exhibited favorable locomotion characteristics that validated the proposed approach.
... Similar conflicting results have in addition been reported for kinematic studies on different single-leg tasks, including the SLS [11,79,80]. This might, however, be unsurprising considering the variety of test situations where isokinetic and isometric testing is used in different positions [16,[81][82][83] with different body-size normalisations [16,83,84]. Furthermore, it seems that the association between hip strength and knee valgus might be conditional on task demand [80] and that there is a gender difference in the performance of the SLS [17,81,84,85]. ...
... Similar conflicting results have in addition been reported for kinematic studies on different single-leg tasks, including the SLS [11,79,80]. This might, however, be unsurprising considering the variety of test situations where isokinetic and isometric testing is used in different positions [16,[81][82][83] with different body-size normalisations [16,83,84]. Furthermore, it seems that the association between hip strength and knee valgus might be conditional on task demand [80] and that there is a gender difference in the performance of the SLS [17,81,84,85]. ...
Background
The Single Leg Squat (SLS) test is widely used in the clinical setting to examine and evaluate rehabilitation goals. It is simple to perform and is proposed to have biomechanical and neuromuscular similarities to athletic movements. The aim of the present study was to investigate whether demographics, previous injuries, and biomechanical and psychosocial factors are associated with the outcome of the SLS, assessed as a total score for all segments and as a separate knee segment in elite and sub-elite female soccer players.
Methods
We conducted a cross-sectional study involving 254 female soccer players (22 yrs; SD ± 4, height 1.69 m; SD ± 0.1, weight 64 kg; SD ± 6) from divisions 1–3 of the Swedish Soccer League. During the preseason, we assessed the participants using the SLS and tested their hip strength and ankle mobility. Demographics, previous injury, sleep quality, fear of movement, anxiety, and perceived stress were assessed with questionnaires. Logistic regression models were built to analyse the association between the outcome of the SLS and the independent variables for the dominant and non-dominant leg.
Results
Significantly more participants failed the SLS on the dominant leg compared with the non-dominant leg (p < 0.001). The outcome of the SLS associated with various biopsychosocial factors depending on if the dominant or non-dominant leg was tested. The total score associated with hip strength for the dominant (OR 0.99, 95% CI 0.98–0.99, p = 0.04) and the non-dominant leg (OR 0.99, 95% CI 0.97–0.99, p = 0.03). The knee segment associated with division level for the dominant (div 2; OR 2.34, 95% CI 1.01–5.12, p = 0.033. div 3; OR 3.07, 95% CI 1.61–5.85, p = 0.001) and non-dominant leg (div 2; OR 3.30, 95% CI 1.33-8.00, p = 0.01. div 3; OR 3.05, 95% CI 1.44–6.43, p = 0.003).
Conclusions
This study identified that leg dominance, division level, hip strength, and psychosocial factors were associated with the outcome of the SLS when assessed as a total score and as a separate knee segment. This indicates that clinicians need to understand that movement control is associated with factors from several domains. Whether these factors and, the results of the SLS are related to injury need to be studied prospectively.
Trial registration
Clinical Trials Gov, date of registration 2022-03-01. Clinical trials identifier: NCT05289284A.
... In addition, the lateral pelvic shift is closely related to the function of the Gmed because it reduces the moment arm of the body weight [35]. flexion [22,31] or full extension [25,32]. The base of support varies depending on the degree of flexion of the lower leg, and a decrease in the base of support can increase Gmed activation during SHA [25]. ...
... In this study, we used the number of HAPCA as a variable indicating the hip abduction performance. In general, an HHD is used to measure force[12,22,31,32]. However, the HHD has a subjective effect on the measurement results depending on the user, and it is difficult to quantify the force in the absence of the HHD. ...
... Patients with a history of hip groin pain, sports hernia, muscle injuries, patellar tendinopathies, ankle joint injuries, and functional or structural dysmetria were excluded from this study. In fact, different studies showed that patients with Patello Femoral Pain Syndrome (PFPS) exhibit greater ipsilateral trunk tilt, contralateral pelvic drop, hip adduction, and knee abduction in the SLST than those without PFPS [22][23][24]. ...
... The postural dysfunction of excessive hip adduction, valgus knee, pelvic obliquity, and ipsilateral trunk tilt has often been associated with lumbar stress injuries [48], PFPS [38,40], and ACL injuries [23]. ...
(1) Background: Optimal neuromuscular, Lumbo-Pelvic-Hip Complex, and lower extremity control are associated with decreased risk factors for secondary anterior cruciate ligament (ACL) injury. This study aimed to analyze any asymmetries and malalignments in the Lumbo-Pelvic-Hip Complex and the lower limbs at 6 months after ACL reconstruction (ACLR). (2) Methods: We conducted an exploratory retrospective observational single-center study in patients during the outpatient postoperative rehabilitation program at ICOT (Latina, Italy). From January 2014 to June 2020, 181 patients were recruited, but only 100 patients (86 male 28 ± 0.6 years, 178 ± 0.5 height; 14 female 24 ± 2.0 years, 178 ± 3.0 height) were eligible for the inclusion criteria and studied 6 months after ACL reconstruction surgery. (3) Statistical analysis: Student's t-tests and Pearson's product-moment correlation coefficient were used to determine significant differences between affected and non-affected limbs and variables' association. (4) Results: The study shows a decrease in neuromuscular control of the Lumbo-Pelvic-Hip Complex and dynamic adaptive valgus of the knee at 6 months after ACLR (mean difference between pathological and healthy limb of dynamic adaptive valgus was −10.11 ± 8.19° 95% CI −14.84 to −9.34; mean value was 16.3 ± 6.8° 95% CI 14.04 to 18.55 for healthy limb and 4.2 ± 3.1° 95% CI 3.15 to 5.21 for pathological limb, p < 0.0001). The results also showed a relationship between dynamic adaptive valgus and contralateral pelvic drop (r = 0.78, 95% CI 0.62 to 0.88, magnitude of correlation very large). (5) Conclusions: The analysis showed an associative correlation between decreased postural control of the pelvic girdle and dynamic adaptive valgus of the knee in 38% of patients; this study highlights the usefulness of the Single-Leg Squat Test (SLST) as a clinical/functional assessment to evaluate the rehabilitation process and as a preventive tool to reduce the risk of second ACL injuries during the return to sport.
... The single leg squat was chosen to functionally assess gluteal performance, as it has been shown to correlate to weakness of the hip extensors. [16][17][18] Observational analysis during the single leg squat demonstrated greater hip adduction and internal rotation on the right. ...
... Signs of weakness of the right gluteus maximus (e.g., during MMT and single leg squat) [16][17][18] were also thought to contribute to decreased pelvic rotation induced through the rear limb during the swing. This would result in a need • Elbow flexed to 90º: ...
Background
Valgus extension overload syndrome (VEOS) of the elbow is a condition associated with overhead athletes. However, the non-surgical management of these individuals is not well documented.
Purpose
To discuss the unique presentation, management, and outcomes of an adolescent baseball player with a chronic history of VEOS experienced during hitting.
Case Description
A 15-year-old right-handed high school baseball catcher presented with a six-month history of right-sided ulnar elbow pain. Elbow MRI w/ contrast was consistent with VEOS. The initial examination demonstrated excessive resting right-sided humeral external rotation compared to his left. Valgus stress testing in the subject’s hitting position reproduced symptoms, which were alleviated with retest while correcting excessive humeral external rotation. Weakness of the humeral internal rotators and stiffness/shortness of the posterior shoulder were found and thought to relate to the humeral contribution to his elbow movement dysfunction. Rehabilitation emphasized addressing impairments contributing to excessive humeral external rotation with reintegration into batting.
Outcomes
After five weeks of physical therapy, the subject returned to soft toss hitting at approximately 75% velocity for the first time since symptom onset, without pain. At seven months after discharge, a phone conversation confirmed that the subject had returned to baseball without limitations.
Discussion
Despite the concept of ‘regional interdependence’, common proximal impairments are often assumed to contribute to elbow pain without a clear biomechanical rationale. Future research demonstrating the specific biomechanical effects of the shoulder on the elbow is needed, in addition to more accessible examination strategies to assess their relationship.
Level of Evidence
5
... Lower ankle dorsiflexion range of motion (DF ROM) [16] and hip abductor weakness [17] have been associated with poor lower limb alignment. While subjects with ankle DF ROM deficit try to compensate it with excessive movement in the frontal or transverse planes of motion [18], the hip abductor weakness contributes to excessive hip adduction and internal rotation related to excessive knee abduction [2]. ...
... However, after controlling the analysis by the intervenient factors which contribute to lower limb aligment, we found that PFP people had: (i) a lower GMed, TA and FIB EMG amplitude; and (ii) similar DVI and EMG amplitude of EO, TFL, VL, VM and RF during single-leg squat. Hip and trunk strength were the most significant predictor of the variation in the knee FPPA during a single leg squat in PFP people [17], which might be related to an impairment in EMG amplitude [31]. Our results did not show differences in EO, GMed and TFL EMG amplitude during a single-leg squat. ...
Purpose
Lower limb alignment during weight-bearing tasks have been associated with ankle dorsiflexion range of motion (DF ROM) and hip abductors muscles' strength. It remains unclear which differences exist on kinematics and proximal, local and distal muscle activation between patellofemoral pain (PFP) and asymptomatic people after controlling the analysis by these measures.
Methods
Thirty women (PFP, n = 15 [age 26.33 ± 4.18 years; body mass index: 24.51 ± 3.61 kg/m²]; asymptomatic—CG, n = 15 [age: 29 ± 5.23 years; body mass index: 23.12 ± 3.31 kg/m²]) completed the following tests: (i) passive ankle DF ROM and (ii) hip abductor isometric strength. After that, the participants performed five repetitions of single-leg squat. Frontal plane kinematics (using dynamic valgus index—DVI) and normalized EMG amplitude of the trunk [External Oblique (EO)], hip [Gluteus Medius (GMed) and Tensor Fascia Latae (TFL)], knee [Vastus Lateralis (VL), Rectus Femoris (RF), Vastus Medialis (VM)] and ankle/foot [Fibularis Longus (FIB) and Tibialis Anterior (TA)] were obtained during squat and compared between groups.
Results
PFP had a lower TA EMG amplitude (−54.19%; p = 0.002). After controlling the analysis by DF ROM and hip abductor strength, PFP had: (i) lower GMed EMG amplitude (−17.42%; p = 0.041); (ii) lower FIB EMG amplitude (−46.80%; p = 0.029); (iii) lower TA EMG amplitude (−53.42%; p = 0.004).
Conclusions
Ankle DF-ROM and hip abductor strength seems to influence on lower proximal and distal EMG amplitude observed during the single-leg squat in women with PFP. Future studies needs to consider an all-encompassing lower limb approach to better understand the sensorimotor control which contributes to lower limb alignment in PFP people.
... Conversely, modifiable factors, including muscle strength and activation, neuromuscular control, and ankle range of motion, have been previously linked to DKV [2]. For instance, a commonly proposed cause of DKV is weak hip abductors, extensors, and external rotators [18][19][20][21], although conflicting results have been found [22,23]. Furthermore, limited ankle dorsiflexion has also been shown to be associated with DKV [24]. ...
The knee is a complex joint essential for locomotion, providing stability that is crucial for avoiding biomechanical deviations such as dynamic knee valgus (DKV), a contributing injury risk factor. This study aimed to assess the influence of body mass index (BMI), age, sex, anthropometric variables, visual feedback, and drop height on the occurrence of DKV. Forty healthy adults aged between 18 and 45 years, with a BMI between 18.5–29.9 kg/m² and no lower limb injuries, were evaluated. Participants underwent a standardized warm-up, anthropometric measurements, and a single-leg drop-landing test from 20 to 30 cm, with and without visual feedback. Women exhibited significantly higher DKV in nearly all conditions. Statistically significant differences were observed between legs when no feedback was provided. Visual feedback significantly reduced DKV in one condition (left limb at 30 cm). Significant weak negative correlations with DKV were found for age, BMI, thigh length, and leg length. These data suggest that women may have higher DKV, anatomical variables may be associated with DKV, and visual feedback may have the potential to attenuate its occurrence. These findings highlight the importance of targeted interventions to attenuate DKV and underscore the role of body awareness and feedback in improving knee alignment.
... Core strength is essential for stabilising the trunk and controlling lower extremity movements, as highlighted by Cobb et al. (2014), Rodrigues et al. (2021), andStickler et al. (2015). Their biomechanical chain approach emphasises the interdependence of core and lower limb function in minimising knee stress. ...
Recent advancements in managing Patellofemoral Pain Syndrome (PFPS) highlight the potential of Blood Flow Restriction (BFR) training, education, and low-intensity exercises as innovative interventions. Combining BFR with neuromuscular control has shown promise in enhancing strength at lower intensities. This study assessed the feasibility of incorporating BFR, education, and low-intensity physiotherapy exercises into PFPS rehabilitation, evaluating recruitment, retention, treatment delivery, and intervention implementation. While no statistically significant differences were found, clinically meaningful improvements in muscle strength, function, and quality of life were observed. These findings support the need for more extensive trials to refine and confirm the intervention's effectiveness in musculoskeletal rehabilitation.
... Dynamic knee valgus has been documented in the literature to be an abnormal movement pattern, and excessive DKV during dynamic activities such as cutting, running, and landing has been linked to several lower extremity injuries which include patellofemoral pain (de Marche Baldon et al., 2009), and anterior cruciate ligament injuries (Hewett et al., 2005;Jones et al., 2014). Females have been shown to display greater DKV during athletic movements in comparison to males which may contribute to the increase in injury risk (Ford et al., 2003(Ford et al., , 2007Hewett et al., 2005;Krosshaug et al., 2007;Stickler et al., 2015). ...
Objectives: This study had three aims 1) explore the relationship between eccentric hip abduction (HABd) and magnitudes of asymmetry in males and females, 2) determine the effect of sex on magnitude of asymmetry and 3) investigate the association of sex on direction of asymmetry. Participants: 61 athletes (39 males, 22 females) participating in multidirectional sports. Main outcome measures: Eccentric HABd strength was tested in both legs for all participants using an eccentric break test with a Handheld dynamometer (HHD). Results: A statistically significant weak positive relationship was found between HABd strength and magnitude of asymmetry in males only. Females demonstrated statistically significant higher magnitude of asymmetry values (15.3%) compared to males (9.8%) (p=0.1). There was no association between sex and direction of asymmetry (absolute: χ2(1) = .24, p = .62, adjusted: χ2(1) = 1.15, p = .28). Conclusion: Female athletes are likely to have greater eccentric HABd asymmetry, but it is not know how this influences performance or injury risk.
... 2,5,28 Compensations observed in the single leg squat such as knee valgus, trunk rotation, and excessive trunk flexion are attributed to gluteal muscle weakness. 8,53,56,57 This muscle group is important for stabilizing the trunk during single leg support, which is necessary for efficient function of the kinetic chain during the softball pitch. This is supported by Friesen et al, 28 who determined compensations during the single leg squat were associated with pathomechanics during the softball pitch. ...
Context
Despite fastpitch softball’s growing popularity, there is limited evidence-based guidance to aid practitioners in developing pitching-specific injury prevention and performance enhancement strategies. This commentary describes the biomechanics across each phase of the softball pitch and provides explanation of common biomechanical errors during the pitch as well as training strategies and exercise recommendations to foster optimal pitcher development.
Evidence Acquisition
A review of softball pitching biomechanics research available in electronic databases including PubMed, Medline, and EBSCO.
Study Design
Clinical review.
Level of Evidence
Level 4.
Results
The 4 primary phases of the windmill softball pitch include the wind-up, stride, acceleration, and follow-through.
Conclusion
Specific training strategies are recommended to combat the various flaws associated with each phase of the softball pitch. Evaluating body composition, functional characteristics like strength and range of motion of the shoulders, trunk, and hips, as well as assessing energy flow may result in improved performance and minimize risk of injury.
... The single-leg squat (SLS) serves as a practical assessment tool applicable in both clinical and sports settings, providing insights into the load on the anterior cruciate ligament, patellofemoral joint, and lumbopelvic-hip complex. [1][2][3][4][5] Visual assessment and 2-dimensional (2D) frontal plane video analysis reliably detect postural malalignments during the SLS test, including excessive pelvic drop, trunk lateral leaning, hip adduction, and knee valgus. 6 Criteria have been proposed for visual assessment to categorize movement quality, enhancing the clinical utility of the SLS. ...
Objective : The aim of this study is to compare kinematic data of the frontal trunk, pelvis, knee, and summated angles (trunk plus knee) among categorized grades using the single-leg squat (SLS) test, to classify the SLS grade, and to investigate the association between the SLS grade and the frontal angles using smartphone-based markerless motion capture. Methods : Ninety-one participants were categorized into 3 grades (good, reduced, and poor) based on the quality of the SLS test. An automated pose estimation algorithm was employed to assess the frontal joint angles during SLS, which were captured by a single smartphone camera. Analysis of variance and a decision tree model using classification and regression tree analysis were utilized to investigate intergroup differences, classify the SLS grades, and identify associations between the SLS grade and frontal angles, respectively. Results : In the poor group, each frontal trunk, knee, and summated angle was significantly larger than in the good group. Classification and regression tree analysis showed that frontal knee and summated angles could classify the SLS grades with a 76.9% accuracy. Additionally, the classification and regression tree analysis established cutoff points for each frontal knee (11.34°) and summated angles (28.4°), which could be used in clinical practice to identify individuals who have a reduced or poor grade in the SLS test. Conclusions : The quality of SLS was found to be associated with interactions among frontal knee and summated angles. With an automated pose estimation algorithm, a single smartphone computer vision method can be utilized to compare and distinguish the quality of SLS movement for remote clinical and sports assessments.
... Jacobs & Mattacola, 2005;C. A. Jacobs et al., 2007;Jordan et al., 2024;Liu et al., 2021;Malloy et al., 2016;Martinez et al., 2018;McCurdy et al., 2014;Munkh-Erdene et al., 2011;Neamatallah et al., 2020;Norcross et al., 2009;Nunes et al., 2022;Radzak & Stickley, 2020;Rodriguez et al., 2020; Soares Souza de Vasconcelos et al., 2023;Stickler et al., 2015;Tate et al., 2017;Vadász et al., 2022;Venable et al., 2022;Vianna et al., 2024;Willson & Davis, 2009;Zeitoune et al., 2020;Zipser et al., 2021). ...
... A single leg squat requires greater stability, neuromuscular control, and balance than a traditional squat. Some studies have shown a relationship between hip abductor weakness and poor single leg squat form, 12,13 but this relationship is limited 14 and the test should not be used to screen for hip abductor weakness. 15 While better single leg squat form is seen in more active individuals, 16 the relationship between single leg squat form and fall risk is unknown. ...
Background
While a high incidence of pickleball-related falls is reported, little is known regarding factors differentiating persons with and without a fall history during play.
Purpose
This study aimed to determine differences between recreational pickleball players who fell while playing and those who did not. Additional aims were to determine reasons for falling and to investigate associations among assessed factors.
Study design
Cross-sectional study.
Methods
Participants completed a survey reporting age, fall history, and reasons for falling during play. Hip abduction strength, single leg squat form, ankle dorsiflexion, and change of direction time using a modified T-test on a pickleball court (i.e. pickleball T-test) were assessed.
Results
Among the 92 individuals participating in the study, 42% reported a fall while playing and 30% reported falling more than once. Leading reasons for reported falls were lunging and moving backward. Participants who reported falling were significantly older (z = -2.60, p = 0.009) and slower on the pickleball T-test (z = -2.10, p = 0.036) than those who did not report falling. Hip abduction strength was not associated with fall history but was associated with faster time on the pickleball T-test (left r s = -.41, p < 0.001, right r s = -.48, p < 0.001). Single leg squat form and dorsiflexion were not related to fall history.
Conclusion
Falls are common among recreational pickleball players, particularly older players. Fall prevention programs for pickleball players should be considered including multi-directional lunging, lower extremity strength and power development, and change of direction training that includes moving backward.
Level of evidence
2
... Svensson et al. [18] found that the hamstring muscle has less strength in the dominant leg when compared to the non-dominant leg due to its constant use for power generation through the knee extensors, resulting in a greater disproportion between the quadriceps and hamstring. These asymmetrical muscle strengths cause differences in movement while performing a squat assessment [19]. in contrast, dix et al. revealed in a meta-analysis that lower extremity valgus was consistently associated with hip strength in singleleg ballistic tasks, but not in the single-leg squat and doubleleg ballistic tasks. in this study, they concluded that the relationship between the leg was conditioned by the task [20]. ...
Introduction
Individual participation in sports with inadequate preparation, especially during competition, results in an increased incidence of injury. Athletes commonly suffer from lower extremity musculoskeletal pain. During growth, several biomechanical factors contribute to muscular imbalance, which results in injury. The aim of the current study was to determine the correlation between lower extremity strength and balance in relation to single leg squat depth.
Methods
A total of 100 male football players were included in the study. Lower extremity qualitative and quantitative squat analyses were performed for both legs. Isometric strength and balance for the lower extremities were assessed via a dynamometer and the Y balance test, respectively.
Results
There is a moderate correlation between the visual squat performance and the strength of the hip extensor in the dominant leg and the hip abductors in the non-dominant leg. A moderate correlation of the maximum squat depth was found with the hip abductors, hip extensor, and knee flexor on the dominant side. The p value was < 0.05 and the r value was between 0.50 and 0.70, which was considered significant.
Conclusions
Strength and balance both influence squat performance. Balance has a stronger influence than strength in single leg squat performance.
... In this context, Stickler et al. indicated that core strength, determined by the side-plank isometric test, was positively related to knee valgus. A 10% change in core strength normalized to body weight leads to a 1.79° improvement in knee valgus [42]. Among the reasons for the positive effect of the STOP-X program in reducing the knee valgus angle with an effect size of 81% in the present study were CST and strength training to strengthen the hip and core muscles (e.g., front planks, side planks, dynamic planks, single-leg and double-leg squats, and jumping exercises). ...
Background
Dynamic knee valgus (DKV) accompanied by poor balance is the cause of anterior cruciate ligament (ACL) injury in athletes, and the identification and correction of these factors are always of interest to researchers. Therefore, the purpose of this research was to investigate the effect of the STOP-X program on the knee valgus angle and static and dynamic balance in female basketball players with DKV defects.
Methods
The present study was a quasi-experimental study. Thirty female basketball players with DKV defects were purposefully identified by the single-leg landing (SLL) test and were randomly assigned to two control (n = 15) and experimental (n = 15) groups. Static balance status was evaluated with the BASS STICK test, and dynamic balance status was evaluated with the Y-balance test (YBT). The experimental group performed the STOP-X program for 25–40 min for eight weeks (three times per week), and the control group performed their traditional warm-up program. Data were analyzed by means of 2 × 2 repeated measures ANOVA followed by post hoc comparison (Bonferroni) at the significance level of (P < 0.05) with SPSS version 26.
Results
The results showed that with the use of the STOP-X program, there was a significant difference between the experimental and control groups in variables of the static balance (F = 56.45; P = 0.001; ES = 0.66, PC=↑59.64%), total dynamic balance score (F = 107.57; P = 0.001; ES=↑0.79, PC=↑19.84%), and knee valgus angle (F = 119.46; P = 0.001; ES = 0.81, PC=↓34.36%).
Conclusion
In addition to reducing the knee valgus angle, applying the STOP-X injury prevention program can improve static and dynamic balance in female basketball players with DKV defects. Therefore, it can be recommended that sports trainers benefit from these advantages by adding STOP-X training to routine basketball exercises.
... Research has proven the importance of core stability in producing efficient and effective limb and trunk movements to generate, transmit and control force and energy during integrated kinematic chain activities [15], for example, Hodges and Richardson studied the sequence of muscle activation during total body motions and found that some stabilizers of the central region (transversusabdominis, multifidus, rectus abdominis, and internal and external obliques) are activated before any movement in the limbs [16,17]. These muscles are also responsible for maintaining the alignment of the pelvis, so that the weakness of these muscles leads to the loss of the correct pelvis alignment, followed by disruption of the length-tension relationship of the muscles of the lower extremity that are connected to this area, and causes a decrease in efficiency and the exposure of the lower extremity to injuries [18]. ...
Purpose: The present study aimed to investigate the effect of six weeks of Pilates exercises on the function of the upper and lower extremities in middle-aged women with lower crossed syndrome (LCS). Methods: This study was a quasi-experimental research with a pre-test-post-test design. The participants included 30 females with LCS from Tiam Sport Club. They were selected using a purposive sampling method and randomly divided into Pilates exercises and control groups. The function of the upper extremity was assessed using Y and Davies tests, and the lower extremity function was assessed using side hop and square hop tests. The Pilates training program was implemented for 6 weeks, 3 days a week and each session lasted 30 minutes. Paired t-test and analysis of covariance (ANCOVA) were used to analyze data at a significance level of P≤0.05. Results: The results showed that the Pilates exercise group performed better than the control group in the function tests of the upper and lower extremities (P≤0.05). No significant difference was observed between pre-test and post-test scores in the control group (P>0.05). Conclusion: Based on the results, it can be concluded that Pilates exercises can improve the function of the upper and lower extremities by enhancing the strength and efficiency of core stabilizer muscles. Therefore, it seems rational to suggest physiotherapists and coaches use these exercises in individuals with LCS.
... The neuromuscular deficit can influence lower limb misalignment [9] and is commonly associated with gluteal muscle strength is associated with lower limb misalignment [10,11]. Considering the dynamism of functional single-leg tasks, neuromuscular activation seems to be an essential factor in the dynamic alignment of the limb [12]. ...
Objectives:
Single-leg (SL) tasks are included as assessment and intervention strategies in several dysfunctions due to the inherent motor control requirement. The recruitment of gluteus maximus (GMAX) and medius (GMED) muscles is essential for proper biomechanical control of the knee and hip joints. The study aims to identify the role of gluteal activation in the biomechanical control of the lower limb during SL tasks.
Methods:
This is a systematic review with searches performed in Pubmed, CINAHL, MEDLINE, Web of Science, and Sportdiscus databases. Cross-sectional studies carried out with asymptomatic individuals were selected, containing hip and knee kinematic and kinetic outcomes assessed through 3D or 2D movement analysis and EMG activity of GMED and GMAX muscles. Two independent reviewers performed the procedures to select the studies, determine the methodological quality and extract the data.
Results:
The initial search resulted in 391 studies, and after the assessment procedures, 11 studies were included. Lower GMAX activation was associated with greater hip internal rotation (HIR) excursion and greater HIR moment, and lower GMED activation was associated with greater hip adduction (HAD)/knee abduction (KAB) excursions and greater KAB moment during single-leg squat (SLS).
Conclusions:
The SL tasks showed a relevant association between the gluteal EMG and other biomechanical outcomes, mainly the SLS task. Interpretation must be cautious, as most studies present high and moderate methodological quality, especially on kinetic data.
... 20 In addition, certain kinematics observed during the SLS in the current study have been recently considered compensatory given that they are associated with weak musculature surrounding the LPHC. 4,21,27,30 Instability of the LPHC can manifest in greater deviations of knee valgus, trunk flexion, trunk lateral flexion, and trunk rotation during a dynamic movement. 5 Therefore, the current study's findings noting differences in kinematics between both sides and SLS phase were worth exploring. ...
Background
Single-leg squat (SLS) performance is related to altered mechanics related to injury during the windmill softball pitch; however, it is unknown if SLS kinematics differ between softball pitchers with and without upper extremity pain.
Purpose/Hypothesis
The purpose of this study was to compare knee valgus, trunk rotation, trunk lateral flexion, and trunk flexion during an SLS in collegiate softball pitchers with and without self-reported upper extremity pain. It was hypothesized that those who reported upper extremity pain would show increased compensatory trunk and knee kinematics compared with those without pain.
Study Design
Controlled laboratory study.
Methods
A total of 75 collegiate softball players (mean age, 20.4 ± 1.7 years; mean height, 173.3 ± 7.7 cm; mean weight, 79.1 ± 11.6 kg) participated and were placed in pain (n = 20) or no-pain (n = 55) groups. Participants performed an SLS once per side. Kinematic data were collected at 100 Hz using an electromagnetic tracking system. A 2 (pain vs no pain) × 2 (descent vs ascent) × 2 (drive leg vs stride leg) mixed-design multivariate analysis of variance with Wilks lambda distribution was used to determine differences in drive-leg and stride-leg lower body mechanics between the descent and ascent phases of the SLS between the pitchers in the current study with and without pain.
Results
There was no significant effect in the 3-way interaction between upper extremity pain, side, and phase (Λ = 0.960; F[4, 70] = 0.726; P = .577; η ² = 0.04). However, there were large effects for the phase × side interaction (Λ = 0.850; P = .021; η ² = 0.150). There was a main effect of phase (Λ = 0.283; P < .001; η ² = 0.717).
Conclusion
Study findings indicated that SLS mechanics do not differ between collegiate softball pitchers with and without reported upper extremity pain. Drive-leg mechanics showed more stability in the SLS than stride-leg mechanics.
Clinical Relevance
Softball pitchers are at risk of upper extremity injury. It is important to identify mechanisms that may lead to pain in order to mitigate the risk of injury.
... Each thigh and shank segment had four markers (i.e., cluster markers) placed on it. The participants then performed a double leg squat whereas the researchers adjusted the angle of knee flexion (i.e., 60° and 45°) based on a goniometer and then put an adjustable plinth at the level of the ischial tuberosity to indicate the pre-determined squat depth (23). ...
Introduction: Introduction: Knee valgus which also known as dynamic knee valgus (DKV), is frequently linked to non-contact lower-limb injuries, especially in females. This retrospective study aims to compare the kinematic variables of lower limb joints in physically active females with normal versus excessive DKV during single leg squat (SLS) at 45° and 60° knee flexion. Methods: Based on the outcomes of drop vertical jump screening test, 34 females were recruited and divided into two groups (i.e., normal and excessive DKV). Participants performed SLS at 45° and 60° knee flexion with three-dimensional motion capture and analysis. The kinematic variables of lower limb joints at both knee flexion of SLS were compared across groups using independent T-test. Results: During 45° SLS with the dominant limb, the normal DKV group performed significantly greater hip adduction angle (4.49±3.25°, t(32) = 2.371, p= 0.024) than the excessive DKV group (1.426±4.23°). During 60° SLS with the dominant limb, the normal DKV group showed knee adduction (0.223±0.07°, t(16.048) = 10.707, p=0.001) while the excessive DKV group showed knee abduction (-4.478±1.81°). Conclusion: Females with excessive DKV showed significantly different lower limb kinematics and motion control strategy compared to females with normal range of DKV. The findings highlighted the importance of DKV screening among physically active females, and the rationale for prescribing individualized exercise intervention to prevent lower limb non-contact injuries.
... Considering that strong hip abductor and external rotator muscles may reduce an excessive dynamic knee valgus (Hollman et al., 2009;Stickler et al., 2015), hip-targeted exercises for the posterolateral hip musculature have been recommended (Willy et al., 2019). However, mechanical changes in trunk, hip, knee, ankle and foot joints seem to contribute to poor lower limb alignment during weight-bearing tasks, increasing patellofemoral joint stress and pain (Barton et al., 2012;Collins et al., 2014;Nakagawa et al., 2012). ...
Objective
To verify the effects of replacing exercises targeted on core/hip muscles by exercises targeted on leg/foot muscles in a rehabilitation program for patellofemoral pain (PFP).
Design
Randomized Controlled Trial.
Participants
Fifty women with PFP.
Methods
PFP participants were randomized into the standard rehabilitation group (SRG, n = 25) or distal exercise group (DEG, n = 25). Knee pain, patient-reported function, dynamic knee valgus and muscle strength were measured at baseline and after six and twelve weeks of the program start.
Results
SRG and DEG presented similar responses to rehabilitation (except for muscle strengthening). Knee pain reduced after 6 weeks (SRG: −37.7%, ES = 1.23; DEG: −30%, ES = 0.93) and 12 weeks (SRG: −47.4%, ES = 1.53; DEG: −43.3%, ES = 1.46). Patient-reported function improved after 6 weeks (SRG: +7.3%, ES = 0.45; DEG: +3.8%, ES = 0.22) and 12 weeks (SRG: +14.1%, ES = 0.80; DEG: +8.8%, ES = 0.50). Dynamic knee valgus reduced after 12 weeks (SRG: −29.7%, ES = 0.38; DEG: −34.5%, ES = 0.32). Both groups experienced increases in knee extension strength (SRG: +9%, ES = 0.28; DEG: +6%, ES = −0.29), but only SRG had strength gains for hip abduction (+10%, ES = 0.36) and extension (+11%, ES = 0.44).
Conclusion
Exercises targeted on core/hip muscles can be replaced by exercises targeted on leg/foot muscles in a lower limb exercise-based rehabilitation program for women with PFP.
Clinical trial registration
NCT03663595.
... Each thigh and shank segment had four markers (i.e., cluster markers) placed on it. The participants then performed a double leg squat whereas the researchers adjusted the angle of knee flexion (i.e., 60° and 45°) based on a goniometer and then put an adjustable plinth at the level of the ischial tuberosity to indicate the pre-determined squat depth (23). ...
Introduction: Introduction: Knee valgus which also known as dynamic knee valgus (DKV), is frequently linked to non-contact lower-limb injuries, especially in females. This retrospective study aims to compare the kinematic variables of lower limb joints in physically active females with normal versus excessive DKV during single leg squat (SLS) at 45° and 60° knee flexion. Methods: Based on the outcomes of drop vertical jump screening test, 34 females were recruited and divided into two groups (i.e., normal and excessive DKV). Participants performed SLS at 45° and 60° knee flexion with three-dimensional motion capture and analysis. The kinematic variables of lower limb joints at both knee flexion of SLS were compared across groups using independent T-test. Results: During 45° SLS with the dominant limb, the normal DKV group performed significantly greater hip adduction angle (4.49±3.25°, t(32) = 2.371, p= 0.024) than the excessive DKV group (1.426±4.23°). During 60° SLS with the dominant limb, the normal DKV group showed knee adduction (0.223±0.07°, t(16.048) = 10.707, p=0.001) while the excessive DKV group showed knee abduction (-4.478±1.81°). Conclusion: Females with excessive DKV showed significantly different lower limb kinematics and motion control strategy compared to females with normal range of DKV. The findings highlighted the importance of DKV screening among physically active females, and the rationale for prescribing individualized exercise intervention to prevent lower limb non-contact injuries.
... Knee valgus has been termed the "position of no return" (Ireland, 2002) and is linked to many injuries, including those of the anterior cruciate ligament (ACL). Stickler, Finley and Gulgin (2015) reported that a 1% increase in hip abductor strength reduced knee valgus by 0.216º. Since soccer involves repetitive unilateral limb support situations, in our opinion, players with reduced core strength or endurance can be susceptible to experiencing dynamic knee valgus. ...
Although relationships between lower limb injury and core strength and endurance have been reported, limited research on the risk of knee injury specifically among soccer players exists. This study aimed to compare preseason trunk muscle endurance as well as trunk and hip muscle strength between soccer players who experienced knee injury during their season and those who did not. Dependent variables were also used to predict the risk for injury. This prospective cross-sectional study involved thirty-nine male soccer players (age 19.64±2.84 years, weight 73.94±15.66 kg and height 175.67±9.92 cm). By the end of the season, twelve (30.77%) reported knee injuries. Accordingly, two groups were identified and compared: injured and non-injured. Prone-bridge, side-bridge, trunk flexion and horizontal back extension hold times were used as trunk endurance measures, while peak isokinetic trunk flexor and extensor torques, as well as hip abductor and external rotator torques, were recorded as strength measures. MANOVA showed that only prone-bridge hold time was significantly higher in the non-injured players (p<0.05). Logistic regression showed that prone-bridge hold time and peak isokinetic hip abductor torque were significant predictors of injury (OR=0.97&0.03, respectively). Thus, soccer players with knee injuries have lesser core endurance. Reduced prone-bridge hold time and abductor torque, specifically, are associated with an increased risk of injury.
Background Chronic knee pain is a common problem in volleyball athletes. Interaction of those risk factors are not well understood, especially in females. The aim of this study was to establish gender specific reference values for risk factors, their relative importance for knee pain and their interaction in female volleyball players (n = 62). Methods Range of motion (ROM) of dorsiflexion, knee flexion and hip joint was assessed with a mobile application and strength values of hip and knee were measured with an isokinetic dynamometer (ISOMED2000). Information gain of variables on knee pain were determined and interaction between variables were accessed with association rules including discretization. Results Foot posture index (FPI) and dorsiflexion ROM have the highest information gain, followed by hip internal ROM and external rotation ROM as well as hip abduction strength. Based on discretization following categories have a high occurrence of knee pain: FPI > 3, dorsiflexion ROM < 41°, knee flexion ROM (< 136°), hip internal rotation ROM < 38°, hip external rotation strength < 0.8 Nm/kg, hip abduction strength < 1.4 Nm/kg. Association rules revealed that quadriceps strength is only important if dorsiflexion ROM is below 41° and should exceed 3.6 Nm/kg. High FPI values combined with low ROM such as dorsiflexion (70%), knee flexion (75%) and hip internal rotation (80%) increase likelihood of knee pain. Furthermore, interactions between low strength and ROM increase likelihood of knee pain (100%). Conclusion We conclude, that the combination of categories with high occurrence of knee pain leads to an even further increased likelihood of knee pain, which does not happen in low risk-categories. In order to prevent knee pain various deficits should be prevented in order to minimize the chances of knee pain.
Background
Single-leg squats are frequently featured in training and rehabilitation programs. The use of focus during exercise changes the state of concentration during exercise. This causes changes in muscular activity. No study has been found comparing focusing methods’ effectiveness during single-leg squat movement.
Aim
This study aims to compare the changes in lower extremity muscular activations in cases of external focus, internal focus, and absence of focus.
Methods
The muscular activities (Gluteus Medius, Vastus Lateralis, Vastus Medialis, Rectus Femoris, Biceps Femoris, and Semitendinosus) of the healthy participants included in the study were measured with the surface electromyography (EMG) device. External focus, internal focus and without-focus positions were used.
Results
Seventeen recreationally active participants were included in this study. The muscular activities of the participants, which occurred in three different situations, were measured with the surface electromyography (EMG) device. While the quadriceps were more active in the descent phase, the hamstring muscle group was more active in the ascent phase. The external focus provided more muscular activation than the other two focal conditions.
Conclusion
According to the results of this study, the use of focus during single-leg squat training and rehabilitation may change the muscular response obtained.
When examining postural sway measures of single-leg squat (SLS), there is a lack of consensus on how many trials are required to obtain reliable and clinically relevant data. Forty adults with chronic low back pain performed five consecutive trials of SLS for each side on a portable force plate. The left and right sides were categorized into problem and non-problem sides by Clinical Pilates assessment. SLS performance was characterized by terminal knee flexion angle, squat duration, peak vertical force and postural sway parameters. Data across five trials were first examined with repeated measures analysis of variance; variables with significant differences were further analyzed using intraclass correlation coefficients (ICC). Using all trials as a reference, the reliability of other trial combinations was assessed to examine the potential effects of learning (2-5 squats, 3-5 squats, 4-5 squats), fatigue (1-2 squats, 1-3 squats, 1-4 squats) and steady-state (2-4 squats). For the non-problem side, postural sway measures were highly reliable ([Formula: see text]) regardless of the number of trials analyzed. For the problem side, analyzing the 1-4 squats combination offered consistently reliable results across all postural measures ([Formula: see text]). Thus, it is recommended to analyze the first four consecutive trials to obtain reliable postural sway measures.
This article presents the design, development, and implementation of walking control for the bipedal exoskeleton prototype Co-Ex. The main objective in developing this prototype is to take a successive step toward ambulatory support via an exoskeleton with self-stabilization capability. To attain this goal, Co-Ex is equipped with 8 torque-controllable active joints to provide ambulatory support while ensuring improved environmental interaction. The development of Co-Ex led to the following three contributions: first, self-stabilization capability in 3-D against external disturbances, second, a locomotion control framework that provides dynamically balanced walking behavior in 3-D despite the underactuated leg configuration, and third, a power-aware leg design in which most actuators are deployed around the waist for reduced leg inertia. To verify the self-stabilization and locomotion capabilities of Co-Ex, we conducted a series of experiments using a dummy manikin. As a result, Co-Ex showed self-stabilization behavior against disturbances and exhibited favorable locomotion characteristics that validated the proposed approach.
Background: Dynamic knee valgus (DKV) accompanied by poor balance is the cause of anterior cruciate ligament (ACL) injury in athletes, and the identification and correction of these factors are always of interest to researchers. Therefore, the purpose of this research was to investigate the effect of the STOP-X program on the knee valgus angle and on static and dynamic balance in female basketball players with DKV defects.
Methods: The present study was a quasi-experimental study. The samples of this research included 30 female basketball players with DKV defects who were purposefully selected from the statistical population of female basketball players and were randomly assigned to two control (n=15) and experimental (n=15) groups. Dynamic knee valgus status was evaluated with the single-leg landing (SLL) test, static balance status was evaluated with the BASS STICK test, and dynamic balance status was evaluated with the Y-balance test (YBT). As a warm-up program, the experimental group performed the STOP-X program for 25-40 minutes for eight weeks (three times per week), and the control group performed their traditional warm-up program. The data were analyzed by ANCOVA and paired-samples t tests with SPSS version 26.
Results: The results showed that with the use of the STOP-X program, there was a significant difference between the experimental and control groups in terms of the knee valgus angle (η2=0.72, P=0.001), static balance (η2=0.47, P=0.001), and total dynamic balance score (η2 = 0.74, P = 0.001). Therefore, the experimental group performed better than the control group.
Conclusion: In addition to reducing the knee valgus angle, applying STOP-X preventive warm-up exercises can improve static and dynamic balance in female basketball players with DKV defects. Therefore, it can be recommended that sports trainers benefit from these advantages by substituting STOP-X preventive exercises instead of traditional warm-up.
BACKGROUD
The control of hip and ankle joint movement is important for patients with dynamic knee valgus (DKV), but few studies have used non-elastic taping (NET) to adjust alignment of the hip and ankle joints during overhead squat (OHS) simultaneously in patients with DKV.
OBJECTIVE
We investigated changes in lower extremity joint kinematics and dynamic balance after the application of NET to the hip and ankle joints during OHS.
METHODS
A total of 30 DKV patients participated in this study. We determined the kinematics of the hip, knee, and ankle joints, and scores on the lower quarter Y-balance test (YBT-LQ) during OHS under three conditions (non-taping, NET on hip and ankle, and sham taping).
RESULTS
Hip internal rotation, knee valgus, and the ankle dorsiflexion angle were significantly lower with NET than with non- or sham taping. The hip flexion angle and scores on the YBT-LQ were significantly greater with NET than with non- or sham taping.
CONCLUSIONS
The application of NET while performing a OHS is a useful method for correcting lower extremity alignment in patients with DKV, however, application of NET on the ankle should be considered.
Introduction: Dynamic knee valgus (DKV) along with poor balance is the cause of anterior cruciate ligament (ACL) injury in athletes, and identification and correction of these factors are always of interest to researchers. Therefore, the purpose of this research was to investigate the effect of the STOP-X program on knee valgus angle, static and dynamic balance in female basketball players with DKV defect.
Materials and methods: The present study was a quasi-experimental. The samples of this research included 30 female basketball players with DKV defect who were purposefully selected from the statistical population of female basketball players and were randomly assigned to two control (n=15) and experimental (n=15) groups. Dynamic knee valgus status was evaluated with the single-leg landing (SLL) test, static balance with the BASS STICK test, and dynamic balance with the Y-balance test (YBT). As a warm-up program, the experimental group performed the STOP-X program for 25-40 minutes for eight weeks (three times per week), and the control group did their traditional warm-up program. Data analysis was done by statistical analysis of ANCOVA and Paired-Samples T Test with SPSS version 26.
Results: The results showed that with the use of the STOP-X program, there was a significant difference between the experimental and control groups in the variables of knee valgus angle (η2=0.72, P=0.001), static balance (η2=0.47, P=0.001), and total dynamic balance score (η2 = 0.74, P = 0.001). So that the experimental group performed better performance compared to the control group.
Conclusion: It seems that applying STOP-X preventive warm-up exercises can improve static and dynamic balance in female basketball players with DKV defects, in addition to reducing the knee valgus angle. Therefore, it can be recommended to sports trainers to benefit from the advantages by substituting STOP-X preventive exercises instead of traditional warm-up.
This study aimed to identify the effect of one-leg squat using a slide on hip strength, and Q angle in patients with chronic hip joint pain patients. Thirty participants subjects were recruited for this study. The experimental group applied one-leg squat using a slide and performed to intervention 3 times a week, 4 weeks, 3 sets of 10 times were performed. All participants have measured hip strengths, and Q angle in before and after the intervention. After the interventions, experimental group showed greater improvement in side bridge, hip abduction, external rotation, extension strength and Q angle than in the pre-test (p<.05). This study shows that one-leg squat using a slide improved hip strengths and Q angle in patients with chronic hip joint pain. These findings suggest that the one-leg squat using a slide has a potential for benefits on hip strengths and Q angle.
OBJECTIVE: To summarize the evidence on reliability and criterion validity of hip muscle strength testing using portable dynamometers.
DESIGN: Systematic review with meta-analysis.
LITERATURE SEARCH: Five databases were searched from inception to March 2023.
STUDY SELECTION CRITERIA: We included studies investigating reliability or criterion validity of hip flexor, extensor, abductor, adductor, or internal/external rotator strength testing with portable dynamometers in injury-free individuals or those with pelvic/lower limb musculoskeletal disorders.
DATA SYNTHESIS: We performed meta-analyses for each muscle group, position, and method of fixation. We rated pooled results as sufficient (>75% of studies with correlations ≥0.70), insufficient (>75% of studies with correlations <0.70), or inconsistent (sufficient/insufficient results). We assessed the quality of evidence, created evidence gap maps, and made clinical recommendations.
RESULTS: We included a total of 107 studies (reliability 103, validity 14). The intrarater and interrater reliability for hip muscle strength testing across different positions and methods of fixation was sufficient (intraclass correlation coefficient = 0.78-0.96) with low- to high-quality evidence. Criterion validity was less investigated and mostly inconsistent (very low–to moderate-quality evidence) with a wide range of correlations (r = 0.40-0.93).
CONCLUSION: Hip muscle strength testing using portable dynamometers is reliable. The use of portable dynamometers as clinical surrogates for measuring strength using an isokinetic dynamometer requires further investigation. Clinicians testing hip muscle strength with portable dynamometers should use external fixation seated for hip flexors, prone or supine for hip extensors, side-lying or supine for abductors and adductors, and prone and seated for internal and external rotators. J Orthop Sports Phys Ther 2023;53(11):655-672. Epub 3 October 2023. doi:10.2519/jospt.2023.12045
Introduction:
Following ACL reconstruction (ACLR), deficits in hip muscle strength and relationships to future outcomes are unknown.
Methods:
111 participants one year after ACLR, completed hip external rotation (ER) and internal rotation (IR) strength assessment. At 1 (n = 111) and 5 (n = 74) years post-ACLR, participants completed a battery of functional, symptomatic (Knee Osteoarthritis Outcome Score (KOOS)) and structural assessments (radiography, magnetic resonance imaging (MRI)). Cartilage health of the patellofemoral and tibiofemoral compartments was assessed with the semiquantitative MRI Osteoarthritis Knee Score. Hip rotation strength was compared between-limbs, and relationships between hip strength at 1 year and functional, symptomatic and cartilage outcomes at 1 and 5 years were investigated with regression models.
Results:
The index (ACLR) limb had weaker hip ER (but not IR) strength compared to the contralateral side (standardised mean difference ER = -0.33 (95%CI -0.60, -0.07; IR = -0.11 (95%CI -0.37, 0.15). Greater hip ER and IR strength was associated with superior function at 1 and 5 years, and better KOOS-Patellofemoral symptoms at 5 years. Greater hip ER strength was associated with lower odds of worsening tibiofemoral cartilage lesions at 5 years (odds ratio 0.01, 95%CI 0.00, 0.41).
Conclusion:
Hip rotation strength may play a role in worsening function, symptoms and cartilage health after ACLR.
Background:
Changes in the trunk and lower limbs' sagittal movements may cause patellofemoral pain (PFP) because they influence the forces acting on this joint.
Objectives:
To compare trunk and lower limb sagittal kinematics between women with and without PFP during functional tests and to verify whether sagittal trunk kinematics are correlated with those of the knees and ankles.
Methods:
A total of 30 women with PFP and 30 asymptomatic women performed single-leg squat (SLS) and step-down (SD) tests and were filmed by a camera in the sagittal plane. The trunk inclination angle, forward knee displacement, and ankle angle were calculated.
Results:
The PFP group exhibited less trunk flexion (SLS, p = .006; SD, p = .016) and greater forward knee displacement (SLS, p = .001; SD, p = .004) than the asymptomatic group; there was no significant difference in ankle angle (SLS, p = .074; SD, p = .278). Correlation analysis revealed that decreased trunk flexion was associated with increased forward knee displacement (SLS, r = -0.439, p = .000; SD, r = -0.365, p = .004) and ankle dorsiflexion (SLS, r = -0.339, p = .008; SD, r = -0.356, p = .005).
Conclusion:
Women with PFP present kinematic alterations of the trunk and knee in the sagittal plane during unipodal activities. Furthermore, the trunk and lower limb sagittal movements were interdependent.
Background:
Electrical muscle stimulation (EMS) has been applied in many rehabilitation settings for muscle strengthening, facilitation of muscle contraction, re-education of muscle action, and maintenance of muscle strength and size during prolonged immobilization.
Objective:
The purpose of this study was to investigate effect of 8 weeks of EMS training on abdominal muscle function and to determine whether the training effect could be maintained after 4 weeks of EMS detraining.
Methods:
Twenty-five subjects performed EMS training for 8 weeks. Before and after 8 weeks of EMS training, and after 4 weeks of EMS detraining, muscle size (cross-sectional area [CSA] of the rectus abdominals [RA] and lateral abdominal wall [LAW]), strength, endurance, and lumbopelvic control (LC) were measured.
Results:
There were significant increases in CSA [RA (p< 0.001); LAW (p< 0.001)], strength [trunk flexor (p= 0.005); side-bridge (p< 0.05)], endurance [trunk flexor (p= 0.010); side-bridge (p< 0.05)], and LC (p< 0.05) after 8 weeks of EMS training. The CSA of the RA (p< 0.05) and the LAW (p< 0.001) were measured after 4 weeks of detraining and they were greater than that of the baseline. There were no significant differences in abdominal strength, endurance, and LC between baseline measurements and post-detraining.
Conclusion:
The study indicates that there is less of a detraining effect on muscle size than on muscle strength, endurance, and LC.
Introduction
Core strengthening, balance, and flexibility programs such as Pilates have been advocated to positively impact running mechanics and prevent lower extremity injuries. The purpose of this study was to assess the effects of a 12-week mat-based Pilates exercise program on dynamic knee valgus alignment in runners.
Methods
Thirty-four novice runners, including young male and female adults performed a running protocol at baseline. The protocol consisted of the participants running on a treadmill at a constant five miles per hour (mph) for four minutes. Post-examination, participants were randomly assigned to a Pilates or control group (n = 16 and n = 18, respectively). A certified Pilates instructor gave the Pilates group a 12-week home-based program. To ensure participants in the Pilates group performed exercises correctly, the Pilates instructor conducted the first session, and provided feedback to each participant. Participants in both groups performed the same running testing protocol every four weeks. Knee valgus was measured as the medial displacement of the knee joint center during the running stance phase. Repeated measures Analysis of Variance (RepANOVA) was calculated at baseline and 4-, 8-, and 12-weeks post examinations to compare knee valgus during running.
Results
Although a reduction in dynamic knee valgus was observed within the Pilates group, the RepANOVA analysis revealed this change was not statistically significant.
Conclusions
Pilates mat-based exercises may improve knee valgus after 12 weeks but a larger sample size, longer intervention duration, or a supervised program should be considered for future research to evaluate its effectiveness.
Objective
The purpose of this study was to investigate the association between trunk muscle endurance with change of direction (T test), single leg squat and power performance in the Special Military Police Force (BOPE) of Rio de Janeiro.
Equipments and methods
One hundred and three military men specialized in Special Operation and Tactical Actions were volunteers. Tests were randomly assigned with a minimum ten minutes rest interval in between.
Results
Weak associations were found between the single leg squat and trunk extension (r =0.268; p = 0.006) as well as right side bridge/trunk extensors (RSB/EXT) (r =0.284; p = 0.004) and left side bridge/trunk extensors (LSB/EXT) ratios (r = -0.242; p = 0.014). The medicine ball throw had a weak association with the left side bridge/extension (LSB/EXT) ratio (r = 0.217; p = 0.28). A weak negative association was found between the T test performance and the right side bridge/left side bridge (RSB/LSB) ratio (r = -0.022; p = .822). Despite the discreet result, hip flexion endurance was the only predictor of performance on the single leg squat (R² = 0.063).
Background
While there is substantial information available regarding expected biomechanical adaptations associated with adult running-related injuries, less is known about adolescent gait profiles that may influence injury development.
Research Questions
Which biomechanical profiles are associated with prevalent musculoskeletal lower extremity injuries among adolescent runners, and how do these profiles compare across injury types and body regions?
Methods
We conducted a cross-sectional study of 149 injured adolescents (110 F; 39 M) seen at a hospital-affiliated injured runner’s clinic between the years 2016-2021. Biomechanical data were obtained from 2-dimensional video analyses and an instrumented treadmill system. Multivariate analyses of variance covarying for gender and body mass index were used to compare continuous biomechanical measures, and Chi-square analyses were used to compare categorical biomechanical variables across injury types and body regions. Spearman’s rho correlation analyses were conducted to assess the relationship of significant outcomes.
Results
Patients with bony injuries had significantly higher maximum vertical ground reaction forces (bony: 1.87 body weight [BW] vs. soft tissue: 1.79BW, p=0.05), and a higher proportion of runners with contralateral pelvic drop at midstance (χ²=5.3, p=0.02). Maximum vertical ground reaction forces and pelvic drop were significantly yet weakly correlated (ρ=0.20, p=0.01). Foot strike patterns differed across injured body regions, with a higher proportion of hip and knee injury patients presenting with forefoot strike patterns (χ²=22.0, p=0.01).
Significance
These biomechanical factors may represent risk factors for injuries sustained by young runners. Clinicians may consider assessing these gait adaptations when treating injured adolescent patients.
This review was conducted to identify, summarize, and discuss literature purporting to present normative data for measurements obtained using a hand-held dynamometer (HHD). Relevant literature was identified through electronic searches of 4 databases: PubMed, Science Citation Index, Scopus and Cumulative Index of Nursing and Allied Health. Articles identified via the searches were reviewed to determine if they presented normative data obtained with a HHD from healthy individuals. Articles were excluded if the data were not presented within age and gender strata. Data on testing and participant specifics were retrieved. Fifteen studies presented normative data within age and gender strata for measurements obtained with a HHD. Norms were presented for neck flexion and numerous actions at the shoulder, elbow, wrist, fingers, hip, knee and ankle. Norms were presented for a wide age span- children to older adults. Many of these norms are compromised. Norms for older adults (≥ 80 years) are lacking. Although norms are available, they should be used with caution. Specifics of testing and samples tested restrict the applicability of the measures.
Anterior knee pain (AKP), also known as patellofemoral pain syndrome (PFPS), is believed to be common in young, active females. A prevalence rate of 25% has been commonly cited in the literature. However, this rate may be more anecdotal than empirical. The purpose of this study was to estimate the prevalence of AKP in females 18 to 35 years of age.
Three cohorts of females, totaling 724 participants between 18 and 35 years of age participated in this study. The mean age of participants was 24.17 years (SD: 2.34), mean height was 165.10 cm (SD: 7.26), mean weight was 65.46 kg (SD: 14.10), and mean BMI was 23.95 kg/m2 (SD: 4.86). Participants completed the Anterior Knee Pain Questionnaire (AKPQ), a functional outcome tool developed to document symptoms of AKP and progress in patients during rehabilitation.
The mean score on the AKPQ for the left lower extremity was 93.38 (SD: 10.00) and 93.16 (SD: 11.37) for the right lower extremity. Using a cutoff score of 83 on the AKPQ, 85 of 724 subjects were classified as having AKP in the left lower extremity for a prevalence of 12% (95% CI = 9%-14%) while 94 subjects were classified with AKP in the right lower extremity for a prevalence of 13% (95% CI = 11%-15%).
The estimated prevalence of AKP in this sample of 18-35 year old females of 12-13% is much less than the commonly cited value of 25%. The results may provide a better representation of subjects with AKP.
3.
To determine the association of 2-dimensional (2D) video-based techniques and 3-dimensional (3D) motion analysis to assess potential knee injury risk factors during jump landing.
Observational study.
Research laboratory.
Thirty-six female athletes in cutting and pivoting sports.
: Athletes performed a drop vertical jump during which movement was recorded with a motion analysis system and a digital video camera positioned in the frontal plane.
The 2D variables were the frontal plane projection angle (FPPA), the angle formed between thigh and leg, and the knee-to-ankle separation ratio, the distance between knee joints divided by the distance between ankles. The 3D variables were knee abduction angle and external abduction moment. All variables were assessed at peak knee flexion. Linear regression assessed the relationship between the 2D and 3D variables. In addition, intraclass correlation coefficients (ICC) determined rater reliability for the 2D variables and compared the 2D measurements made from digital video with the same measurements from the motion analysis.
: The knee-to-ankle separation ratio accounted for a higher variance of 3D knee abduction angle (r = 0.350) and knee abduction moment (r = 0.394) when compared with the FPPA (r = 0.145, 0.254). The digital video measures had favorable rater reliability (ICC, 0.89-0.94) and were comparable with the motion analysis system (ICC, ≥ 0.92).
When compared with the FPPA, the knee-to-ankle separation ratio had better association with previously cited knee injury risk factors in female athletes. The 2D measures have adequate consistency and validity to merit further clinical consideration in jump landing assessments.
Excessive frontal plane motion and valgus torques have been linked to knee injuries, particularly in women. Studies have investigated the role of lower extremity musculature, yet few have studied the activation of trunk or "core" musculature on hip and knee kinematics. Therefore, this study evaluated the influence of intentional core engagement on hip and knee kinematics during a single leg squat.
Participants (n = 14) performed a single leg squat from a 6 inch step under 2 conditions: core intentionally engaged (CORE) and no intentional core engagement (NOCORE). Participants were also evaluated for core activation ability using Sahrmann's model, and the resulting scores were used to divide participants into low (LOWCORE) and high scoring (HIGHCORE) groups. All trials were captured using 3-D motion analysis, and data were normalized for height and time. Paired t-tests and repeated measures, mixed model MANOVAs were used to assess condition and group differences.
The CORE condition, compared to NOCORE, was characterized by smaller right [t(13) = 3.03, p = .01] and left [t(13) = 3.04, p = .01] hip frontal plane displacement and larger knee flexion range of motion [t(13) = 3.08, p = .009]. Subsequent MANOVAs and follow-up analyses revealed that: (1) the CORE condition demonstrated smaller right and left hip medial-lateral displacement in the LOWCORE group (p = .001), but not in the HIGHCORE group; (2) the CORE condition showed larger overall knee flexion range of motion across LOWCORE and HIGHCORE groups (p = .021); and (3) the HIGHCORE group exhibited less knee varus range of motion across CORE and NOCORE conditions (p = .028).
Intentional core activation influenced hip and knee kinematics during single leg squats, with greater positive effect noted in the LOWCORE group. These findings may have implications for preventing and rehabilitating knee injuries among women.
2B, Cohort laboratory study, mixed model design.
Two-dimensional (2D) video analysis of frontal-plane dynamic knee valgus during common athletic screening tasks has been purported to identify individuals who may be at high risk of suffering knee injuries such as anterior cruciate ligament tear or patellofemoral pain syndrome. Although the validity of 2D video analysis has been studied, the associated reliability and measurement error have not.
To assess the reliability and associated measurement error of a 2D video analysis of lower limb dynamic valgus.
Reliability study.
20 recreationally active university students (10 women age 21.5 ± 2.3 y, height 170.1 ± 6.1 cm, weight 66.2 ± 10.2 kg, and 10 men age 22.6 ± 3.1 y, height 177.9 ± 6.0 cm, weight 75.8 ± 7.9 kg).
Within-day and between-days reliability and measurement-error values of 2D frontal-plane projection angle (FPPA) during common screening tasks.
Participants performed single-leg squat and drop jump and single-leg landings from a standard 28-cm step with standard 2D digital video camera assessment.
Women demonstrated significantly higher FPPA in all tests except the left single-leg squat. Within-day ICCs showed good reliability and ranged from .59 to .88, and between-days ICCs were good to excellent, ranging from .72 to .91. Standard error of measurement and smallest detectable difference values ranged from 2.72° to 3.01° and 7.54° to 8.93°, respectively.
2D FPPA has previously been shown to be valid and has now also been shown to be a reliable measure of lower extremity dynamic knee valgus. Using the measurement error values presented along with previously published normative data, clinicians can now make informed judgments about individual performance and changes in performance resulting from interventions.
Controlled laboratory study using a cross-sectional design.
To compare patellofemoral joint kinematics, femoral rotation, and patella rotation between females with patellofemoral pain (PFP) and pain-free controls using weight-bearing kinematic magnetic resonance imaging.
Recently, it has been recognized that patellofemoral malalignment may be the result of femoral motion as opposed to patella motion.
Fifteen females with PFP and 15 pain-free females between the ages of 18 and 45 years participated in this study. Kinematic imaging of the patellofemoral joint was performed using a vertically open magnetic resonance imaging system. Axial-oblique images were obtained using a fast gradient-echo pulse sequence. Images were acquired at a rate of 1 image per second while subjects performed a single-limb squat. Measures of femur and patella rotation (relative to the image field of view), lateral patella tilt, and lateral patella displacement were made from images obtained at 45 degrees , 30 degrees , 15 degrees , and 0 degrees of knee flexion. Group differences were assessed using a mixed-model analysis of variance with repeated measures.
When compared to the control group, females with PFP demonstrated significantly greater lateral patella displacement at all angles evaluated and significantly greater lateral patella tilt at 30 degrees , 15 degrees , and 0 degrees of knee flexion. Similarly, greater medial femoral rotation was observed in the PFP group at 45 degrees , 15 degrees , and 0 degrees of knee flexion when compared to the control group. No group differences in patella rotation were found.
Altered patellofemoral joint kinematics in females with PFP appears to be related to excessive medial femoral rotation, as opposed to lateral patella rotation. Our results suggest that the control of femur rotation may be important in restoring normal patellofemoral joint kinematics. J Orthop Sports Phys Ther 2010;40(5):277-285, Epub 12 March 2010. doi:10.2519/jospt.2010.3215.
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.
Lower extremity (LE) weakness might be associated with altered mechanics during weight bearing in subjects with patellofemoral pain syndrome (PFPS).
To analyze LE strength, mechanics, and the association between these variables among women with and without PFPS during a simulated athletic task.
Case control. Setting: Motion-analysis laboratory.
20 women with PFPS and 20 healthy women.
Peak isometric lateral trunk-flexion, hip-abduction, hip external-rotation, knee-flexion, and knee-extension strength, as well as hip- and knee-joint excursions and angular impulses during single-leg jumps.
PFPS subjects produced less hip-abduction, hip external-rotation, and trunk lateral-flexion force than the control group. The PFPS group also demonstrated greater hip-adduction excursion and hip-abduction impulses. The association between the strength measurements and LE mechanics was low.
Women with PFPS demonstrate specific weaknesses and altered LE mechanics. Weakness is not, however, highly correlated with observed differences in mechanics.
Do females with patellofemoral pain syndrome have decreased hip muscle strength compared with the unaffected side and with healthy controls?
A systematic review of observational studies published up to January 2008.
Females with patellofemoral pain syndrome and healthy controls.
Strength for at least one hip muscle group had to be included in the study. Hip muscle strength was recorded as force or torque.
Five cross-sectional studies with a mean Newcastle-Ottawa Assessment Scale score of 6 out of 9 met the inclusion criteria. Strong evidence was found for a deficit in hip external rotation, abduction and extension strength, moderate evidence for a deficit in hip flexion and internal rotation strength, and no evidence for a deficit in hip adduction strength compared with healthy controls. Moderate evidence was found for a decrease in hip external rotation and abduction strength but no evidence for a decrease in hip extension, flexion, adduction and internal rotation strength compared with the unaffected side.
Females with patellofemoral pain syndrome demonstrate a decrease in abduction, external rotation and extension strength of the affected side compared with healthy controls.
Controlled laboratory study using a cross-sectional design.
To determine whether females with patellofemoral pain (PFP) demonstrate differences in hip kinematics, hip muscle strength, and hip muscle activation patterns when compared to pain-free controls.
It has been proposed that abnormal hip kinematics may contribute to the development of PFP. However, research linking hip function to PFP remains limited.
Twenty-one females with PFP and 20 pain-free controls participated in this study. Hip kinematics and activity level of hip musculature were obtained during running, a drop jump, and a step-down maneuver. Isometric hip muscle torque production was quantified using a multimodal dynamometer. Group differences were assessed across tasks using mixed-design 2-way analyses of variance and independent t tests.
When averaged across all 3 activities, females with PFP demonstrated greater peak hip internal rotation compared to the control group (mean +/- SD, 7.6 degrees +/- 7.0 degrees versus 1.2 degrees +/- 3.8 degrees; P<.05). The individuals in the PFP group also exhibited diminished hip torque production compared to the control group (14% less hip abductor strength and 17% less hip extensor strength). Significantly greater gluteus maximus recruitment was observed for individuals in the PFP group during running and the step-down task.
The increased peak hip internal rotation motion observed for females in the PFP group was accompanied by decreased hip muscle strength. The increased activation of the gluteus maximus in individuals with PFP suggests that these subjects were attempting to recruit a weakened muscle, perhaps in an effort to stabilize the hip joint. Our results support the proposed link between abnormal hip function and PFP.
Numerous factors have been identified as potentially increasing the risk of anterior cruciate ligament injury in the female athlete. However, differences between the sexes in lower extremity coordination, particularly hip control, are only minimally understood.
There is no difference in kinematic or electromyographic data during the single-legged squat between men and women.
Descriptive comparison study.
We kinematically and electromyographically analyzed the single-legged squat in 18 intercollegiate athletes (9 male, 9 female). Subjects performed five single-legged squats on their dominant leg, lowering themselves as far as possible and then returning to a standing position without losing balance.
Women demonstrated significantly more ankle dorsiflexion, ankle pronation, hip adduction, hip flexion, hip external rotation, and less trunk lateral flexion than men. These factors were associated with a decreased ability of the women to maintain a varus knee position during the squat as compared with the men. Analysis of all eight tested muscles demonstrated that women had greater muscle activation compared with men. When each muscle was analyzed separately, the rectus femoris muscle activation was found to be statistically greater in women in both the area under the linear envelope and maximal activation data.
Under a physiologic load in a position commonly assumed in sports, women tend to position their entire lower extremity and activate muscles in a manner that could increase strain on the anterior cruciate ligament.
Decreased lumbo-pelvic (or core) stability has been suggested to contribute to the etiology of lower extremity injuries, particularly in females. This prospective study compares core stability measures between genders and between athletes who reported an injury during their season versus those who did not. Finally, we looked for one or a combination of these strength measures that could be used to identify athletes at risk for lower extremity injury.
Before their season, 80 female (mean age = 19.1 +/- 1.37 yr, mean weight 65.1 +/- 10.0 kg) and 60 male (mean age = 19.0 +/- 0.90 yr, mean weight 78.8 +/- 13.3 kg) intercollegiate basketball and track athletes were studied. Hip abduction and external rotation strength, abdominal muscle function, and back extensor and quadratus lumborum endurance was tested for each athlete.
Males produced greater hip abduction (males = 32.6 +/- 7.3%BW, females = 29.2 +/- 6.1%BW), hip external rotation (males = 21.6 +/- 4.3%BW, females = 18.4 +/- 4.1%BW), and quadratus lumborum measures (males = 84.3 +/- 32.5 s, females = 58.9 +/- 26.0 s). Athletes who did not sustain an injury were significantly stronger in hip abduction (males = 31.6 +/- 7.1%BW, females = 28.6 +/- 5.5%BW) and external rotation (males = 20.6 +/- 4.2%BW, females = 17.9 +/- 4.4%BW). Logistic regression analysis revealed that hip external rotation strength was the only useful predictor of injury status (OR = 0.86, 95% CI = 0.77, 0.097).
Core stability has an important role in injury prevention. Future study may reveal that differences in postural stability partially explain the gender bias among female athletes.
Increased knee valgus predicts the risk of anterior cruciate ligament (ACL) injury, particularly in women. Reducing injury rates thus relies on detecting and continually evaluating people with relatively large valgus motions.
To examine the potential of a two dimensional (2D) video analysis method for screening for excessive valgus.
Ten female and 10 male National Collegiate Athletic Association basketball players had three dimensional (3D) knee valgus and two dimensional (2D) frontal plane knee angle quantified during side step, side jump, and shuttle run tasks. 3D valgus was quantified from external marker coordinates using standard techniques, and 2D data were obtained from both the frontal plane projections of these coordinates (2D-Mot) and manual digitization of digital video footage (2D-Cam). A root mean square (RMS) error was calculated between 2D-Mot and 2D-Cam data to evaluate the reliability of the latter. Correlations between 2D-Cam and 3D data (intersubject and intrasubject) were also conducted, and regression slope and r2 values obtained.
2D-Cam and 2D-Mot data were consistent for side step (RMS = 1.7 degrees) and side jump (RMS = 1.5 degrees) movements. Between subjects, 2D-Cam and 3D data correlated well for the side step (r2 = 0.58) and side jump (r2 = 0.64). Within subjects, 2D-Cam and 3D data correlated moderately for the side step (r2 = 0.25 (0.19)) and side jump (r2 = 0.36 (0.27)).
The 2D-Cam method can be used to screen for excessive valgus in elite basketball players, particularly for movements occurring primarily in the frontal plane. This method may also be a useful training evaluation tool when large reductions in dynamic valgus motions are required.
The purpose of this study was to determine the relationship between hip and knee strength, and valgus knee motion during a single leg squat. Thirty healthy adults (15 men, 15 women) stood on their preferred foot, squatted to approximately 60 deg of knee flexion, and returned to the standing position. Frontal plane knee motion was evaluated using 3-D motion analysis. During Session 2, isokinetic (60 deg/sec) concentric and eccentric hip (abduction/adduction, flexion/extension, and internal/external rotation) and knee (flexion/extension) strength was evaluated. The results demonstrated that hip abduction (r2=0.13), knee flexion (r2=0.18), and knee extension (r2=0.14) peak torque were significant predictors of frontal plane knee motion. Significant negative correlations showed that individuals with greater hip abduction (r=-0.37), knee flexion (r=-0.43), and knee extension (r=-0.37) peak torque exhibited less motion toward the valgus direction. Men exhibited significantly greater absolute peak torque for all motions, excluding eccentric internal rotation. When normalized to body mass, men demonstrated significantly greater strength than women for concentric hip adduction and flexion, knee flexion and extension, and eccentric hip extension. The major findings demonstrate a significant role of hip muscle strength in the control of frontal plane knee motion.
Patellofemoral pain (PFP) is a commonly presenting disorder of the lower limb, frequently effecting young physically active individuals particularly females. The condition has been associated with poor control of limb alignment while undertaking unilateral limb loading tasks. This poor alignment of the limb is believed to alter loading stress within the patellofemoral joint. This study aims to investigate the degree of knee valgus, assessed as 2D frontal plane projection angle (FPPA) during single leg squatting (SLS) and hop landing (SLL) tasks in patients with PFP and compare their performance to controls and the uninjured limb.
Twelve female subjects with unilateral PFP formed the patient group and thirty asymptomatic females formed the control group. They had their 2D frontal plane projection angle (FPPA) assessed during single leg squatting (SLS) and hop landing (SLL) tasks.
In the asymptomatic control group the mean FPPA for SLS was 8.4±5.1° and SLL had a mean FPPA of 13.5±5.7°. In the PFP group the mean FPPA for SLS was 16.8±5.4° and SLL had a mean FPPA of 21.7+/-3.6°, these differences were significant (p<0.01) for both tasks.
Patients with PFP have a greater degree of knee valgus on unilateral limb loading task than either their contralateral asymptomatic limb or an asymptomatic control group. If not corrected this may lead to further PFJ stress and ongoing morbidity.
[Purpose]: The aim of this study was to evaluate whether using a belt to restrain a hand-held dynamometer improves reliability of isometric lerg muscle stength measurements i healthy subjects. [Subjects]: Twenty to 44 healthy subjects participated in the test. [Methods]: Two raters, one man and one woman, used a hand-held dynamometer with or without a restraining belt to measure the isometric strengths of the following muscle groups: flexors, extensors, abductors, internal rotators and external rotators of the hip; flexors and extensors of the knee; and dorsiflexors and plantar flexors of the ankle. [Results]: The intraclass correlation coefficient, used to describe interrater agreement, ranged from 0.97 to 0.99 with the belt and from 0.21 to 0.88 without the belt. Pearson's correlation coefficient for measurements with versus without the belt ranged from 0.61 to 0.95 for the man and from 0.31 to 0.87 for the woman. [Conclusion]: The interrater reliability of isometric leg muscle strength measurements was improved by used of a belt to restrain the hand-held dynamometer.
Purpose:
Patellofemoral pain (PFP) is the leading cause of knee pain in runners. Proximal and distal running mechanics have been linked to the development of PFP. However, the lack of prospective studies limits establishing a causal relationship of these mechanics to PFP. The purpose of this study was to prospectively compare running mechanics in a group of female runners who went on to develop PFP compared with healthy controls. It was hypothesized that runners who go on to develop PFP would exhibit greater hip adduction, hip internal rotation, and greater rear foot eversion.
Methods:
Four hundred healthy female runners underwent an instrumented gait analysis and were then tracked for any injuries that they may have developed over a 2-yr period. Fifteen cases of PFP developed, which were confirmed by a medical professional. Their initial running mechanics were compared to an equal number of runners who remained uninjured.
Results:
We found that female runners who developed PFP exhibited significantly greater hip adduction (P = 0.007). No statistically significant differences were found for the hip internal rotation angle (P = 0.47) or rear foot eversion (P = 0.1).
Conclusions:
The finding of greater hip adduction in female runners who develop PFP is in agreement with previous cross-sectional studies. These results suggest that runners who develop PFP use a different proximal neuromuscular control strategy than those who remain healthy. Injury prevention and treatment strategies should consider addressing these altered hip mechanics.
Objectives: No consensus has been reached regarding the incidence and prevalence of patellofemoral pain syndrome (PFPS). This literature review aims to explore and present research conducted on the incidence and prevalence data for PFPS to date.
Methods: The literature search employed databases Ovid SP, AMED, Ovid Medline (R) and EMBASE, accessed via the University of Central Lancashire Library Online service, and search terms 'adolescen*' 'anterior knee pain', 'incidence', 'outcome measure', 'patellofemoral pain', 'patellofemoral pain syndrome', 'prevalence', 'questionnaire' and 'response rate'. All articles were filtered by hand to determine relevance, as were reference lists of applicable studies/reviews to identify key articles. Pertinent journals were included as recommended by a specialist in the field.
Results: Ten studies were selected for review, spanning 22 years of study that apparently focused on incidence over prevalence. Despite a lack of United Kingdom based research, this topic is of international interest. The participant groups demonstrate a large age span, comprising mainly military recruits, along with students, healthcare patients and athletes. The selection and definition of terminology differed greatly, as did methodologies, specifically the data collection tools. Despite questionnaires being well suited to incidence and prevalence data collection, none were identified as being valid and reliable.
Discussion: Two major research gaps were identified: investigation into PFPS prevalence (and incidence) within athletic adolescents, and the development of a questionnaire to collect incidence and or prevalence data. Such research could facilitate clinical practice and the development of health strategies.
It has been postulated that subjects with weak hip abductors and external rotators may demonstrate increased knee valgus, which may in turn raise risk of injury to the lower extremity. Recent studies have explored the potential link between hip strength and knee kinematics, but there has not yet been a review of this literature.
To conduct a systematic review assessing the potential link between hip-abductor or external-rotator strength and knee-valgus kinematics during dynamic activities in asymptomatic subjects.
An online computer search was conducted in early February 2011. Databases included Medline, EMBASE, CINAHL, SPORTDiscus, and Google Scholar. Inclusion criteria were English language, asymptomatic subjects, dynamometric hip-strength assessment, single or multicamera kinematic analysis, and statistical analysis of the link between hip strength and knee valgus via correlations or tests of differences. Data were extracted concerning subject characteristics, study design, strength measures, kinematic measures, subject tasks, and findings with regard to correlations or group differences.
Eleven studies were selected for review, 4 of which found evidence that subjects with weak hip abductors or external rotators demonstrated increased knee valgus, and 1 study found a correlation to the contrary.
There is a small amount of evidence that healthy subjects with weak hip abductors and perhaps weak external rotators demonstrate increased knee valgus. However, due to the variation in methodology and lack of agreement between studies, it is not possible to make any definitive conclusions or clinical recommendations based on the results of this review. Further research is needed.
Diagnosis of patellofemoral pain syndrome (PFPS) is commonly performed using a myriad of clinical and imaging-based criteria.
The objective of this systematic literature review was to summarize the research on accuracy of individual clinical tests/findings for PFPS.
MEDLINE, ProQuest Nursing and Allied Health, Cochrane Trials, PEDro, and CINAHL. STUDY SELECTION OR ELIGIBILITY CRITERIA: PRISMA guidelines were followed for this review. To be considered for review, the study required: (1) a description of a clinical test or tests used for diagnosing PFPS (including a test that was combined with another finding such as patient history), (2) a report of the diagnostic accuracy of the measures (e.g., sensitivity and specificity), and (3) an acceptable reference standard for comparison. STUDY APPRAISAL OR SYNTHESIS METHODS: Quality Assessment of Studies of Diagnostic Accuracy (QUADAS) scores were completed on each selected article. Sensitivity, specificity, and negative and positive likelihood ratios (LR-/LR+) were calculated for each diagnostic test described.
The systematic search strategy and hand search revealed 704 potential articles, 9 of which met the criteria for this review; analysing a total of 22 PFPS clinical tests. After assessment using the QUADAS score, 1 of the 9 articles was of high quality. The tests with the highest reported diagnostic value were also associated with studies that had the lowest QUADAS values.
A majority of the studies that have investigated diagnostic accuracy of clinical tests for PFPS demonstrate notable design or reporting biases, and at this stage, determining the best tests for diagnosis of PFPS is still difficult.
Controlled laboratory study using a cross-sectional design.
To determine whether there are any differences between the sexes in trunk, pelvis, hip, and knee kinematics, hip strength, and gluteal muscle activation during the performance of a single-leg squat in individuals with patellofemoral pain syndrome (PFPS) and control participants.
Though there is a greater incidence of PFPS in females, PFPS is also quite common in males. Trunk kinematics may affect hip and knee function; however, there is a lack of studies of the influence of the trunk in individuals with PFPS.
Eighty subjects were distributed into 4 groups: females with PFPS, female controls, males with PFPS, and male controls. Trunk, pelvis, hip, and knee kinematics and gluteal muscle activation were evaluated during a single-leg squat. Hip abduction and external rotation eccentric strength was measured on an isokinetic dynamometer. Group differences were assessed using a 2-way multivariate analysis of variance (sex by PFPS status).
Compared to controls, subjects with PFPS had greater ipsilateral trunk lean (mean ± SD, 9.3° ± 5.3° versus 6.7° ± 3.0°; P = .012), contralateral pelvic drop (10.3° ± 4.7° versus 7.4° ± 3.8°; P = .003), hip adduction (14.8° ± 7.8° versus 10.8° ± 5.6°; P<.0001), and knee abduction (9.2° ± 5.0° versus 5.8° ± 3.4°; P<.0001) when performing a single-leg squat. Subjects with PFPS also had 18% less hip abduction and 17% less hip external rotation strength. Compared to female controls, females with PFPS had more hip internal rotation (P<.05) and less muscle activation of the gluteus medius (P = .017) during the single-leg squat.
Despite many similarities in findings for males and females with PFPS, there may be specific sex differences that warrant consideration in future studies and when clinically evaluating and treating females with PFPS.
Contemporary clinical expertise and emerging research in anterior knee pain indicate that treatment of hip muscle function will result in greater effects, if such treatments can be provided to those with hip muscle dysfunction. Thus, it is imperative to develop and evaluate a clinical assessment tool that is capable of identifying people with poor hip muscle function.
The clinical assessment of single-leg squat performance will have acceptable inter- and intrarater reliability. Furthermore, people with good performance on the single-leg squat will have better hip muscle function (earlier onset of gluteus medius activity and greater lateral trunk, hip abduction, and external rotation strength) than people with poor performance.
Cohort study (diagnosis); Level of evidence, 2.
A consensus panel of 5 experienced clinicians developed criteria to rate the performance of a single-leg squat task as "good," "fair," or "poor." The panel rated the performance of 34 asymptomatic participants (mean ± SD: age, 24 ± 5 y; height, 1.69 ± 0.10 m; weight, 65.0 ± 10.7 kg), and these ratings served as the standard. The ratings of 3 different clinicians were compared with those of the consensus panel ratings (interrater reliability) and to their own rating on 2 occasions (intrarater reliability). For the participants rated as good performers (n = 9) and poor performers (n = 12), hip muscle strength (hip abduction, external rotation, and trunk side bridge) and onset timing of anterior (AGM) and posterior gluteus medius (PGM) electromyographic activity were compared.
Concurrency with the consensus panel was excellent to substantial for the 3 raters (agreement 87%-73%; κ = 0.800-0.600). Similarly, intrarater agreement was excellent to substantial (agreement 87%-73%; κ = 0.800-0.613). Participants rated as good performers had significantly earlier onset timing of AGM (mean difference, -152; 95% confidence interval [CI], -258 to -48 ms) and PGM (mean difference, -115; 95% CI, -227 to -3 ms) electromyographic activity than those who were rated as poor performers. The good performers also exhibited greater hip abduction torque (mean difference, 0.47; 95% CI, 0.10-0.83 N·m·Bw(-1)) and trunk side flexion force (mean difference, 1.08; 95% CI, 0.25-1.91 N·Bw(-1)). There was no difference in hip external rotation torque (P > .05) between the 2 groups.
Targeted treatments, although considered ideal, rely on the capacity to identify subgroups of people with chronic anterior knee pain who might respond optimally to a given treatment component. Clinical assessment of performance on the single-leg squat task is a reliable tool that may be used to identify people with hip muscle dysfunction.
To investigate the within-day and between-day reliability of 3D lower extremity kinematics during five lower extremity functional screening tests and to assess the association between these kinematics and those recorded during jogging.
Peak three-dimensional lower extremity kinematics were quantified in 25 uninjured participants during five lower extremity functional tests and jogging. A nine camera motion analysis system (Qualysis Medical AB, Sweden) was used to capture three trials of all tests. All functional tests were repeated by 10 participants one to two days later. Visual 3D (C-Motion Inc, USA) and Labview were used to process all data. Intraclass correlation coefficients (ICC) and typical errors (TE) were used to assess within- and between-day reliability of all variables. Pearson correlation coefficients were used to evaluate the association between peak joint kinematics during the functional tests and jogging.
For the majority of kinematic variables the within-day reliability was excellent (ICC ≥ 0.92) and the between-day reliability was excellent to good (ICC ≥ 0.80). The correlation between kinematics of the functional tests and jogging was generally large to very large (r = 0.53 to 0.93).
These results suggest these lower extremity functional screening tests should prove a useful clinical tool when assessing dynamic lower extremity alignment.
Objectives Patients with patellofemoral pain syndrome (PFPS) often demonstrate a collapse of the knee in the medial direction during a one-leg squat. This study investigated the medial displacement magnitude of the knee during a one-leg squat test in females with PFPS.Design The study design was a cross sectional comparative investigation.Participants Thirteen healthy females and 12 females with PFPS.Main measures Participants were tested during a one-leg squat test using a single camera. The thigh segment alignment in the frontal plane was measured by the angle projected between the long axis of the thigh and the foot (femoral frontal angle) and the horizontal deviation (femoral deviation) of the distal thigh relative to the foot.Results A one-way ANOVA showed that the femoral frontal angle was significantly larger (p=0.019) for the PFPS group with no significant differences for the femoral deviation (p=0.288). Both measurements showed good trial-to-trial reliability while the femoral frontal angle showed good test-retest reliability.Conclusion The increased femoral frontal angle magnitude during the one-leg squat demonstrates that the one-leg squat may be a useful clinical tool for the evaluation process of PFPS.
Patellofemoral pain (PFP) is a common musculoskeletal pain condition, especially in females. Decreased hip muscle strength has been implicated as a contributing factor, yet the relationships between pain, hip muscle strength and function are not known. The purpose of this study was to test the hypothesis that pain and hip muscle strength explain unique portions of variance in the functional status of females with PFP.
An observational, cohort study was conducted. The subjects for this study were twenty-one females with PFP (age: 26 +/- 7 years; height: 163 +/- 4 cm; and body mass: 62 +/- 10 kg). Subjects had a minimum pain duration of two months (mean pain duration: 4.9 +/- 3.6 years). The main measures were pain during a unilateral squat, measured with a visual analogue scale; isometric muscle force of gluteus medius, gluteus maximus and hip lateral rotators; and Kujala score (self-report measure of function). Hierarchical multiple regression analysis was performed with Kujala score as the dependent variable. Pain and hip lateral rotator muscle strength were independent variables, entered in that order. Other strength measures were not correlated with the Kujala score, and as such, were not used in the analysis.
Pain explained 22% of the variance in the Kujala score (p = 0.03). Hip lateral rotator strength explained an additional 14% of the variance, after accounting for pain level (p = 0.06).
Pain and hip lateral rotator strength contributed to the functional status of females with PFP. Improving pain and hip lateral rotator muscle strength may improve function in females with this common pain condition.
Reduced strength and activation of hip muscles might correlate with increased weight-bearing knee valgus.
To describe relationships among frontal-plane hip and knee angles, hip-muscle strength, and electromyographic (EMG) recruitment in women during a step-down.
Exploratory study.
Laboratory.
20 healthy women 20 to 30 years of age. Interventions: Frontal-plane hip and knee angles were measured. Gluteus maximus and medius recruitment were examined with surface EMG. Hip-abduction and -external-rotation strength were quantified with handheld dynamometry.
The authors analyzed correlation coefficients between knee and hip angles, gluteus maximus and medius EMG, and hip-abduction and -external-rotation strength.
Hip-adduction angles (r = .755, P = .001), gluteus maximus EMG (r = -.451, P = .026), and hip-abduction strength (r = .455, P = .022) correlated with frontal-plane projections of knee valgus.
Gluteus maximus recruitment might have greater association with reduced knee valgus in women than does external-rotation strength during step-down tasks. Gluteus medius strength might be associated with increased knee valgus.
Controlled bending moments were applied to twelve human cadaver knee joints using a special loading fixture that allowed variation of both the Q-angle and the flexion angle. The joints were tested at three different Q-angles (physiological, increased 10 degrees, and decreased 10 degrees) and five different angles of flexion (ranging from 20 to 120 degrees). Based on one-third of values in the literature for maximum voluntary isometric quadriceps moments, we applied resultant knee moments of 23.6, 30.7, 47.2, and 35.0 newton-meters at 20, 30, 60, and 90 degrees of flexion, respectively. Based on two-thirds of reported maximum moments, we applied 47.2 newton-meters at 120 degrees of flexion. Normal patellofemoral-contact pressures, measured with a pressure-sensitive film, were remarkably uniformly distributed (+/- 0.25 megapascal ), with approximately the same pressure on the lateral and medial patellar facets. The maximum contact force occurred at 90 degrees of flexion. Extrapolating our measurements to full in vivo moments, we estimated maximum contact forces of 4600 newtons , or approximately 6.5 times body weight. Tendofemoral contact at 120 degrees of knee flexion supported one-third of the total contact force on the patella. A 10-degree increase in the Q-angle resulted in increased peak pressures (an increase of 45 per cent at 20 degrees of flexion). A decrease in the Q-angle resulted in unloading of the vertical crest and, in some knees, of parts of the lateral facet. However, these decreases were always associated with increased peak pressures (50 per cent more at 20 degrees of flexion) at other locations.
OBJECTIVE: The purpose of this research was to compare the three-dimensional kinematics of runners exhibiting excessive rearfoot pronation with those having normal rearfoot pronation. DESIGN: The study design was a comparative investigation of two types of running patterns. BACKGROUND: Excessive rearfoot pronation is often linked with overuse injuries of the lower extremity. However, the literature is void of papers describing the rearfoot motion of runners presenting with excessive rearfoot pronation. Many knee-related injuries in runners are associated with increased rearfoot pronation; however, knee mechanics in this population of runners have yet to be studied. Finally, three-dimensional studies are needed to describe joint motion fully during running and these are also lacking. METHODS: Eighteen subjects (nine excessive pronators -- PRs; nine normals -- NLs) were studied during treadmill running at 3.35 m/s. Retroreflective markers were placed on the foot, shank and thigh segments and recorded with four 200 Hz video cameras. Three-dimensional kinematics were computed. RESULTS: A downward shift of the eversion curve was seen in the PR group resulting in an everted position of the rearfoot at both footstrike and toe-off compared with an inverted posture seen in the NL group. The amount of toe-out was not significantly different between the two groups. At the knee, the PR group demonstrated significantly less adduction and significantly greater flexion than the NL. Mean peak velocities of the PR group were greater in all angular measures except knee adduction. However, only foot dorsiflexion and eversion and knee flexion velocities were significantly different. CONCLUSIONS: Kinematic differences were noted at both the rearfoot and the knee of the runners who exhibit excessive rearfoot pronation.
Although patellofemoral pain (PFP) is recognized as being one of the most common disorders of the lower extremity, treatment guidelines and underlying rationales remain vague and controversial. The premise behind most treatment approaches is that PFP is the result of abnormal patellar tracking and/or patellar malalignment. Given as such, interventions typically focus on the joint itself and have traditionally included strengthening the vastus medialis oblique, taping, bracing, soft tissue mobilization, and patellar mobilization. More recently, it has been recognized that the patellofemoral joint and, therefore, PFP may be influenced by the interaction of the segments and joints of the lower extremity. In particular, abnormal motion of the tibia and femur in the transverse and frontal planes may have an effect on patellofemoral joint mechanics. With this in mind, interventions aimed at controlling hip and pelvic motion (proximal stability) and ankle/foot motion (distal stability) may be warranted and should be considered when treating persons with patellofemoral joint dysfunction. The purpose of this paper is to provide a biomechanical overview of how altered lower-extremity mechanics may influence the patellofemoral joint. By addressing these factors, better long-term treatment success and prevention may be achieved.
The purpose of this study was to examine the effects of a comprehensive neuromuscular training program on measures of performance and lower-extremity movement biomechanics in female athletes. The hypothesis was that significant improvements in measures of performance would be demonstrated concomitant with improved biomechanical measures related to anterior cruciate ligament injury risk. Forty-one female basketball, soccer, and volleyball players (age, 15.3 +/- 0.9 years; weight, 64.8 +/- 9.96 kg; height, 171.2 +/- 7.21 cm) underwent 6 weeks of training that included 4 main components (plyometric and movement, core strengthening and balance, resistance training, and speed training). Twelve age-, height-, and weight-matched controls underwent the same testing protocol twice 6 weeks apart. Trained athletes demonstrated increased predicted 1 repetition maximum squat (92%) and bench press (20%). Right and left single-leg hop distance increased 10.39 cm and 8.53 cm, respectively, and vertical jump also increased from 39.9 +/- 0.9 cm to 43.2 +/- 1.1 cm with training. Speed in a 9.1-m sprint improved from 1.80 +/- 0.02 seconds to 1.73 +/- 0.01 seconds. Pre- and posttest 3-dimensional motion analysis demonstrated increased knee flexion-extension range of motion during the landing phase of a vertical jump (right, 71.9 +/- 1.4 degrees to 76.9 +/- 1.4 degrees ; left, 71.3 +/- 1.5 degrees to 77.3 +/- 1.4 degrees ). Training decreased knee valgus (28%) and varus (38%) torques. Control subjects did not demonstrate significant alterations during the 6-week interval. The results of this study support the hypothesis that the combination of multiple-injury prevention-training components into a comprehensive program improves measures of performance and movement biomechanics.
Background:
Differences in anatomical alignment between genders have been suggested as causes of the disparity in anterior cruciate ligament injury rates. A larger Q-angle may be associated with increased knee valgus during movement resulting in anterior cruciate ligament strain. This study investigated whether healthy college-aged subjects with a large Q-angle display greater peak knee valgus during a single limb squat compared to those with a small Q-angle. The study also determined whether the high and low Q-angle groups displayed differences in other select anatomical variables, and whether these anatomical variables were related to knee valgus.
Methods:
Twenty subjects, categorized as having a "high Q-angle" (> or = 17 degrees) or a "low Q-angle" (< or = 8 degrees) were videotaped during the performance of a single leg squat. The peak valgus angles for the right knee were calculated. One-tailed independent measures t-tests were used to determine whether individuals with a large Q-angle exhibit (1) significantly greater peak knee valgus during a single leg squat compared to those with a small Q-angle and, (2) greater pelvic width to femoral length ratios and greater static knee valgus than subjects with a small Q-angle. The Pearson product-moment correlation was used to establish the relationships between pelvic width to femoral length ratios and static knee valgus, pelvic width to femoral length ratios and dynamic knee valgus, and static knee valgus and dynamic knee valgus.
Findings:
Peak knee valgus during the single leg squat, and static knee valgus were not significant greater in the high Q-angle group compared to the low Q-angle group (P=0.09; P=0.31). Subjects with a larger Q-angle, however, had a significantly greater pelvic width to femoral length ratios (P=0.015) compared to subjects with a small Q-angle. Pelvic width to femoral length ratios was related to both static and dynamic knee valgus (r=0.47, P=0.02; r=0.48, P=0.02), but static knee valgus was not related to dynamic knee valgus.
Interpretation:
The findings suggest that pelvic width to femoral length ratios, rather than Q-angle, may be a better structural predictor of knee valgus during dynamic movement.
Muscles of the trunk, hip, and knee influence the orientation of the lower extremity during weight bearing activities. The purpose of this study was threefold: first, to compare the orientation of the lower extremity during a single leg (SL) squat among male and female athletes; second, to compare the strength of muscle groups in the trunk, hips, and knees between these individuals; and third, to evaluate the association between trunk, hip, and knee strength and the orientation of the knee joint during this activity.
Twenty-four male and 22 female athletes participated in this study. Peak isometric torque was determined for the following muscle actions: trunk flexion, extension, and lateral flexion, hip abduction and external rotation, and knee flexion and extension. The frontal plane projection angle (FPPA) of the knee during a 45 degrees SL squat was determined using photo editing software.
Males and females moved in opposite directions during the SL squat test (F(1,42) = 5.05, P = 0.03). Females typically moved toward more extreme FPPA during SL squats (P = 0.056), while males tended to move toward more neutral alignment (P = 0.066). Females also generated less torque in all muscle groups, with the exception of trunk extension. The projection angle of the knee during the SL squat test was most closely associated with hip external rotation strength.
Using instruments suitable for a clinical setting, females were found to have greater FPPA and generally decreased trunk, hip, and knee isometric torque. Hip external rotation strength was most closely associated with the frontal plane projection angle.
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