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. Author manuscript; available in PMC: 2026 Aug 8.
Published in final edited form as: Phys Ther Sport. 2026 Jul 24;81:101968. doi: 10.1016/j.ptsp.2026.101968

HIP JOINT POWER DURING A SINGLE LEG SQUAT IS RELATED TO PATIENT-REPORTED FUNCTION, PHYSICAL ACTIVITY, AND SYMPTOM DURATION IN INDIVIDUALS WITH CHRONIC HIP-RELATED PAIN

Holly M Elliott 1, Bethany J Wilcox 2, Michael A Samaan 1,*, Kate N Jochimsen 3,4,*
PMCID: PMC13449101  NIHMSID: NIHMS2201126  PMID: 42526308

Abstract

Objectives

Analyze associations between lower extremity joint power during the eccentric and concentric phases of a single leg squat and hip symptom duration, hip function, and physical activity levels in individuals with hip joint-related groin pain.

Design

The cross-sectional design of the current study is a secondary analysis of an observational study consisting of a cohort design.

Setting

Biomechanics Laboratory.

Participants

Twenty-five adults aged 18 to 45 years with current hip pain were recruited for this study.

Main Outcome Measures

Participants self-reported quality of life and physical function using the iHOT-12, current activity level using the Tegner Activity Rating Scale, and hip symptom duration. Lower-limb joint power was calculated using three-dimensional biomechanics data. Spearman’s correlation coefficients were used to examine the relationships between parameters.

Results

Our study found that lower hip joint power during the eccentric and concentric phases of a single leg squat task were associated with worse hip function, lower physical activity levels, and a longer duration of hip symptoms.

Conclusions

These findings highlight the importance of early intervention prior to the onset of severe muscle dysfunction that may lead to corresponding alterations in hip joint loading in individuals with hip joint-related pain.

Keywords: Hip-Related Groin Pain, Single-Leg Squat, Hip Power, Hip Symptom Duration

INTRODUCTION

Hip -related pain (HRP) commonly affects young and middle-aged active individuals (Reiman, Agricola, Kemp, Heerey, Weir, van Klij, Kassarjian, Mosler, Ageberg, Holmich, Warholm, Griffin, Mayes, Khan, Crossley, Bizzini, Bloom, Casartelli, Diamond, …, et al., 2020). HRP encompasses non-arthritic, intra-articular hip joint conditions with and without variations in bony morphology (Reiman, Agricola, Kemp, Heerey, Weir, van Klij, Kassarjian, Mosler, Ageberg, Holmich, Warholm, Griffin, Mayes, Khan, Crossley, Bizzini, Bloom, Casartelli, Diamond, Di Stasi, et al., 2020). The conditions associated with variant hip joint morphology include femoroacetabular impingement syndrome (FAIS) and acetabular dysplasia, while non-morphological conditions include labral tears and chondral injuries (Reiman, Agricola, Kemp, Heerey, Weir, van Klij, Kassarjian, Mosler, Ageberg, Holmich, Warholm, Griffin, Mayes, Khan, Crossley, Bizzini, Bloom, Casartelli, Diamond, Di Stasi, et al., 2020). Most individuals with HRP exhibit chronic symptoms (> 3 months in duration) and often reduce physical activity in an attempt to minimize their symptoms (Kemp et al., 2014; King et al., 2021). Although HRP is classified as a movement-related disorder (Griffin et al., 2016), the relationships between important clinical factors – symptom duration, physical activity level, patient-reported hip function and quality of life, and movement patterns remain unclear.

Prior work has shown that a unilateral squatting task is more sensitive in detecting alterations in lower-limb mechanics compared to a bilateral squatting task in individuals with HRP (Malloy et al., 2019). Our prior work demonstrated that individuals with a longer duration of HRP exhibited lower average hip extensor moments during both the eccentric and concentric phases of a single leg squat (SLS) compared to individuals with a shorter symptom duration (Stanze et al., 2025). However, joint moments alone do not fully characterize musculoskeletal function. An adequate amount of joint power, defined as the product of joint moment and joint angular velocity, describes the generation and absorption of energy by the musculature and provides insight into ‘how’ and ‘when’ muscles contract (i.e., eccentric – energy absorption and concentric – energy generation) during dynamic tasks (Grimmer et al., 2023; Winter, 1979; Zajac et al., 2002). Compared to kinematics and moments alone, joint power offers a more direct window into functional muscle capacity.

Prior work has examined joint power during walking and stair climbing in individuals with hip osteoarthritis (OA) (Meyer et al., 2018; Wade et al., 2025) and after total hip arthroplasty (Lunn et al., 2019; Queen et al., 2019). Hip joint power increased after total hip arthroplasty (THA) (Queen et al., 2019), yet low-functioning THA individuals continued to exhibit lower sagittal plane hip joint power than healthy controls (Lunn et al., 2019), suggesting a relationship between hip joint power and function. Our prior work has shown that individuals with FAIS who ambulate with greater sagittal plane hip joint loading at 6 months after surgery exhibit improved cartilage health compared to the pre-surgical time point (Samaan et al., 2020). These findings suggest that quantifying hip joint power production may identify muscular targets needed to optimize hip joint loading and improve clinical outcomes. However, minimal research has examined joint power in the pre-arthritic HRP population (Brisson et al., 2013; Kumar et al., 2014), and phase-specific analysis (eccentric vs. concentric) during the SLS would provide a more detailed characterization of muscle energy absorption and generation throughout the entire lower extremity.

Therefore, the goal of this retrospective study was to analyze associations between lower extremity joint power during the eccentric and concentric phases of a SLS and hip symptom duration, hip function, and physical activity levels in individuals with HRP.

METHODS

This is a secondary analysis of an observational study, consisting of a cohort design, in individuals with chronic HRP. Study methods were approved by the West Virginia University (WVU) IRB (Study protocols #2205585218 and 2106336942), and data from this study have been previously published (Stanze et al., 2025). Adults aged 18 to 45 years old with current hip pain were recruited from the community. Individuals under the age of 18 were excluded because patient-reported outcome measures have not been validated in pediatric populations, and those over the age of 45 were excluded to minimize the risk of enrolling patients with osteoarthritis (Young et al., 2020). Individuals were screened on the phone for inclusion/exclusion criteria. Individuals must have had their current hip and/or groin pain most days of the week for a minimum of 3 months (i.e., chronic). They were excluded if they had a history of prior hip joint surgery to the involved hip, a history of slipped capital femoral epiphysis (SCFE) or Legg-Calve-Perthes disease, or current spine or other lower extremity injuries other than their current hip pain. Those who met these criteria came into the lab for a clinical screening by the PI. The clinical screening included a flexion/adduction/internal rotation (FADIR) impingement test, flexion/abduction/external rotation (FABER) test, straight leg raise test, and full lower quarter screen. To be included, individuals must have had a positive FADIR test, a negative straight leg raise test, and a negative lower quarter screen. They may have had a positive FABER test for pain in the anterior hip/groin. However, if they had a positive FABER test for pain in the low back/sacroiliac joint, they were excluded. These methods have been used in prior HRP studies to categorize a group of patients with similar clinical presentations (Harris-Hayes et al., 2016). All participants provided written and verbally informed consent prior to participation.

DATA COLLECTION

A total of 25 participants were recruited and tested in this study (Table 1). After providing informed consent, participants completed questionnaires to establish baseline demographics (age, sex, gender, symptom duration [months], race, ethnicity, and symptomatic hip). They also completed patient-reported outcome measures, including the iHOT-12 and the Tegner Activity Rating Scale. The iHOT-12 is a shorter version of the International Hip Outcome Tool (iHOT-33) and is a valid and reliable patient-reported outcome tool for measuring health-related quality of life and physical function in young, active individuals with HRP (Cheng et al., 2025; Scholes et al., 2021; Thorborg et al., 2015). Scores on the iHOT-12 range from 0 to 100, where 0 represents the poorest quality of life and physical function, and 100 represents the highest quality of life and physical function. The Tegner Activity Rating Scale is a valid and reliable single-item measure that asks participants to rate their current activity level (Negahban et al., 2011). The scale ranges from 0 to 10, where 0 represents complete disability and 10 represents elite-level sporting competition. Although the Tegner was originally developed to quantify physical activity in patients with knee injuries, it has since been used robustly with other lower extremity injury populations, including the hip (Lutz et al., 2026). Each participant’s height (m) and mass (kg) were recorded.

Table 1.

Subject Demographics and Clinical Variables Reported in Median [Interquartile Range] for Non-Normally Distributed Variables and Mean ± Standard Deviation for Normally Distributed Variables. Hip Symptom Duration Is Reported as the Median [Range].

Age (years) BMI (kg/m2) Sex (Females: Males) Hip Symptom Duration (months) Hip Function (iHOT-12) Current Physical Activity (Tegner)
23 [18–39] 25.55 ± 4.03 19:6 36 [3–204] 50.10± 15.43 5 [2–8]
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Three-dimensional (3D) biomechanics data were collected using rigid marker clusters that were placed on the upper thorax, pelvis and bilaterally on the upper arms, forearms, thighs, shanks and superior aspect of the foot (Stanze et al., 2025). Kinematic and ground reaction force (GRF) data were recorded simultaneously using a 10-camera motion analysis system captured at a frequency of 240 Hz (Vicon, Hauppauge, NY) and 2 in-ground force platforms captured at a frequency of 1200 Hz (Bertec, Worthington, OH). A standing calibration trial was used to determine segment position and ankle, knee, and hip joint centers. Segments were calibrated using the 7th cervical vertebrae, 12th thoracic vertebra, 5th lumbar vertebra, bilateral posterior superior iliac spines (PSIS), bilateral anterior superior iliac spines (ASIS), bilateral greater trochanter, bilateral medial and lateral knee joint line, bilateral medial and lateral malleoli, and bilateral second phalanx. All data were collected through TheMotionMonitor xGen software (Innovative Sports Training, Inc, Chicago, IL).

Prior to performing the SLS task, participants were provided verbal instructions to place their arms across their chest, transfer their weight to a single leg, squat down as far as they could, and return to a standing position. All participants performed the SLS on the non-symptomatic leg first, followed by the symptomatic leg. Participants were allowed to familiarize themselves with the task prior to data collection, and then performed three successful trials per leg, one at a time, resting between trials. Trials were considered unsuccessful if participants lost their balance, put their non-test limb down, or uncrossed their arms.

DATA PROCESSING & ANALYSIS

Marker position and GRF data were filtered using a bidirectional 4th order, lowpass Butterworth filter with a 20 Hz cutoff frequency. The squat cycle was defined based on the vertical center of mass (COM) position of the pelvis. Maximum squat depth was defined using the minimum vertical COM position of the pelvis. The initiation and termination events for each SLS trial were defined using a change in position of the vertical COM greater than 2.5 standard deviations from quiet standing. Each trial was time-normalized from initiation to termination of the SLS (0 – 100%). Joint power (Watts/kg) was calculated as the product of joint moment (Nm/kg) and joint angular velocity (rad/s).

The SLS was split into the eccentric (descent phase) and concentric phases (ascent phase) using the minimum COM vertical position. The summation of the hip, knee, and ankle joint powers during both the eccentric and concentric phases of the SLS were used to calculate the total power for both phases. Peak total power was found during both the eccentric and concentric phases and the corresponding hip, knee, and ankle joint power magnitudes at the peak total power were extracted for both phases. Eccentric and concentric power were assigned negative and positive values, respectively. Hip, knee, and ankle joint percent contributions to the peak total power during the eccentric and concentric phases were calculated by dividing the corresponding joint power magnitude by the total power and multiplying by 100%.

Statistical analysis was performed using JASP Statistics (JASP, Version 0.95.3; JASP Team, 2025). Shapiro-Wilk test for normality was used to assess for normality across all power parameters, clinical variables, and demographics. Descriptive statistics were calculated for demographics and clinical variables including age, sex, BMI, symptom duration, iHOT-12 scores, and Tegner Activity Scale. Demographics and clinical variables are reported as the mean and standard deviation, median and interquartile range, ratio, or range from minimum to maximum as appropriate. Spearman’s correlation coefficients were used to examine the relationships between power parameters during the SLS task, and clinical variables including hip function (iHOT-12), hip symptom duration, and current physical activity (Tegner Activity Scale). Effect size was calculated for each parameter using Cohen’s d values (Cohen, 1988), where a value of 0 – 0.2, 0.21 – 0.5 and > 0.5 were classified as small, medium, and large effect sizes, respectively. Statistical significance for the correlation analyses was set at an alpha level of 0.05.

RESULTS

There were 25 individuals included in this study (Table 1). Subjects ranged from 18 to 39 years of age, with 6 males and 19 females. Symptom duration ranged from 3 to 204 months with a median duration of 36 months. Notably, one subject had substantially longer symptom duration (204 months) compared to the rest of the group (3–100 months), though their inclusion did not impact the results. To assess the impact on the main findings, we performed a post hoc sensitivity analysis. We repeated all analyses with the outlier excluded. The direction and significance of the associations did not change, confirming the results are not driven by the outlier. Joint power parameters during the eccentric and concentric phases of the SLS are displayed in Table 2. Significant correlations were found between sagittal plane hip power absorption at peak total eccentric power and sagittal plane hip power generation at peak total concentric power with hip function, symptom duration, and current physical activity level (Figure 1, Table 3). Specifically, lower hip power magnitude during both phases (eccentric and concentric) was associated with worse hip function scores, longer symptom duration, and lower current physical activity.

Table 2.

Primary Outcome Variables Reported as the Mean ± Standard Deviation.

Eccentric Phase Concentric Phase
Peak Total Power (W/kg) −2.51 ± 1.15 3.51 ± 1.85
Peak Hip Power (W/kg) −0.89 ± 0.75 1.42 ± 1.12
Peak Knee Power (W/kg) −1.36 ± 0.61 1.75 ± 0.87
Peak Ankle Power (W/kg) −0.26 ± 0.14 0.34 ± 0.15
Percent Hip Contribution (%) 32.45 ± 16.36 37.08 ± 14.32
Percent Knee Contribution (%) 55.49 ± 12.93 51.71 ± 11.67
Percent Ankle Contribution (%) 12.05 ± 6.86 11.21 ± 5.41
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Figure 1.

Figure 1.

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Scatter Plots Representing Correlations Between Peak Hip Power Parameters and Clinical Variables.

Table 3.

Spearman’s Rho Correlations Between Peak Hip Power Parameters and Clinical variables.

Hip Symptom Duration (months) Hip Function (iHOT-12) Current Physical Activity (Tegner)
Peak Hip Eccentric Power (W/kg) rho = 0.54 (p = 0.005; Cohen’s d = 1.283) rho = −0.46 (p = 0.02; Cohen’s d = −1.036) rho = −0.55 (p = 0.004; Cohen’s d = −1.317)
Peak Hip Concentric Power (W/kg) rho = −0.44 (p = 0.03; Cohen’s d = −0.980) rho = 0.42 (p = 0.04; Cohen’s d = 0.926) rho = 0.58 (p = 0.002; Cohen’s d = 1.424)
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DISCUSSION

The purpose of this study was to examine the relationships between sagittal plane hip joint power during the eccentric and concentric phases of a SLS with hip symptom duration, hip function, and physical activity levels in individuals with HRP. The results indicated a lower sagittal plane hip joint power at peak total power during both the eccentric and concentric phases of the SLS was associated with worse hip function, lower physical activity levels, and longer HRP symptom duration. Therefore, hip joint power may be a clinically relevant target in individuals with HRP.

Individuals with HRP exhibit altered lower extremity muscle function (Casartelli et al., 2011; Frasson et al., 2020; Harris-Hayes et al., 2020; Kierkegaard, Mechlenburg, et al., 2017; Nepple et al., 2015), which may present differently during the eccentric and concentric phases of a SLS task. Prior work demonstrated that individuals with HRP exhibit lower hip extension moment during the SLS (Malloy et al., 2019; Stanze et al., 2025). The current findings extend this work by demonstrating that lower sagittal plane hip joint power during both the eccentric and concentric phases of the SLS is associated with worse clinical and functional patient-reported outcomes, suggesting that individuals with HRP are both generating (concentric phase) and absorbing (eccentric phase) less energy through the hip flexors and extensors during the SLS task. This pattern mirrors findings in low-functioning patients after total hip arthroplasty, who similarly exhibit lower sagittal plane hip joint power compared to healthy controls (Lunn et al., 2019) and supports sagittal plane hip joint power as a potentially clinically relevant mechanical biomarker of physical function within the HRP population. Furthermore, lower hip joint power may reflect lower overall hip joint loading during the SLS, which is a possible compensatory strategy to reduce the demand on the symptomatic hip when performing a task where offloading the symptomatic limb is not possible. These data provide additional evidence for the SLS task as a sensitive biomechanical task for detecting movement alterations in patients with HRP.

Moderate mechanical loading is necessary to maintain optimal articular cartilage health (Griffin & Guilak, 2005), and chronically reduced joint loading may therefore be detrimental to overall joint health and function. This is consistent with prior work showing that hip underloading is associated with worse cartilage composition in individuals that undergo hip arthroscopy for FAIS (Samaan et al., 2020) as well as worse structural cartilage health in athletes with HRP (Crossley et al., 2026). Exercise-based interventions have been shown to improve strength and function in individuals with HRP (Harris-Hayes et al., 2021; Kemp et al., 2018; Kierkegaard, Langeskov-Christensen, et al., 2017); however, non-operative and post-operative rehabilitation for HRP must be improved to provide adequate symptomatic relief, promote favorable hip joint loading, and prevent disease progression or the need for surgical intervention. Collectively, these results highlight sagittal plane hip joint power as a potential therapeutic target in rehabilitation.

Current non-operative rehabilitation for HRP yields only modest improvements in pain and function, with a response rate of approximately 50% (Probst et al., 2023). A key contributor to these outcomes is the absence of high-quality evidence to guide intervention selection and clinical decision making. The current Clinical Practice Guidelines (CPGs) for HRP do not recommend any interventions with Grade A evidence (Enseki et al., 2023), reflecting the lack of rigorous data. Existing rehabilitation protocols largely focus on hip strength, movement pattern optimization, and range of motion (Harris-Hayes et al., 2016; Hoit et al., 2020; Ishoi et al., 2021; Mortensen et al., 2018). The role of hip power, the capacity to rapidly generate and absorb energy, remains underutilized as a specific intervention target. Given the associations identified in the current study between lower hip joint power and worse clinical outcomes, hip joint power training may represent a key ingredient missing from current rehabilitation protocols. Targeting phase-specific hip joint power may be able to directly address underlying muscle dysfunction and altered joint loading. Patients with eccentric power deficits may benefit from tempo-controlled descent or progressive deceleration exercises to improve the hip’s capacity to absorb load during functional and sport-specific tasks. Exercises for patients with concentric deficits may benefit from progressive resistance and explosive strengthening exercises to restore force generation capacity. Evaluating squat phases separately may provide rehabilitation clinicians with more granular benchmarks for tracking treatment response and ensuring patients have restored the ability to load their hip safely and generate force effectively before returning to high level function or sport.

There are some limitations in the current study that should be considered. Firstly, the cross-sectional study design introduces both selection bias and recall bias in the self-reporting of hip function and current physical activity levels. The cross-sectional study design also limits the ability to determine causal relationships within our results. Additionally, with a mostly female cohort and small overall sample size, we cannot draw definitive conclusions regarding hip joint power in the HRP population. Radiographic imaging was not obtained for the participants and therefore limits our ability to diagnose specific hip-related conditions. Data was not collected for an asymptomatic control group, therefore eliminating our ability to make comparisons between groups. While sex-specific differences have been shown in lower-limb biomechanics during both high and low impact tasks in individuals with HRP (King et al., 2019), these sex-specific differences were not accounted for in the current study.

CONCLUSIONS

Our study found that lower hip joint power during the eccentric and concentric phases of a SLS task were associated with worse hip function, lower physical activity levels, and a longer duration of hip symptoms. These findings highlight the importance of early intervention prior to the onset of severe muscle dysfunction that may lead to corresponding alterations in hip joint loading in individuals with HRP. In addition, our study findings suggest that sagittal plane hip joint power may be an ideal biomechanical target for HRP rehabilitation. Future work should investigate the effects of hip joint power training on clinical and disease-specific outcomes including hip joint loading, hip cartilage health, severity of hip pain, and physical activity level.

Figure 2.

Figure 2.

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Total Joint Power Related Variables During the Single Leg Squat Task.

HIGHLIGHTS.

  • Lower hip power is associated with worse hip function,

  • Lower hip power is associated with lower physical activity

  • Lower hip power is associated with longer symptom duration

  • Hip joint power may be an ideal biomechanical target for HRP rehabilitation

  • Earlier intervention to optimize hip power may mitigate severe muscle dysfunction

FUNDING

This work was funded by the American College of Sports Medicine Mid-Atlantic Regional Chapter (MARC-ACSM) Early-Stage Investigator Award and West Virginia University Research and Scholarship Advancement (RSA) Grant. NIH Award (K23-AT011922). NIH Award (K01-AG073698).

Footnotes

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DECLARATION OF INTEREST

None

Statement of Human Rights

Study methods were approved by the West Virginia University (WVU) IRB (Study protocols #2205585218 and 2106336942), and data from this study have been previously published (Stanze et al., 2025).

Declaration of interests

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:

Kate N. Jochimsen reports financial support was provided by American College of Sports Medicine Mid-Atlantic Regional Chapter (MARC-ACSM) Early-Stage Investigator Award. Kate N. Jochimsen reports financial support was provided by West Virginia University Research and Scholarship Advancement (RSA) Grant. Kate N. Jochimsen reports financial support was provided by NIH Award (K23-AT011922). Michael A. Samaan reports financial support was provided by NIH Award (K01-AG073698). If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

REFERENCES

  1. Alshameeri Z, & Khanduja V. (2014). The effect of femoro-acetabular impingement on the kinematics and kinetics of the hip joint. Int Orthop, 38(8), 1615–1620. 10.1007/s00264-014-2302-5 [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bagwell JJ, Snibbe J, Gerhardt M, & Powers CM. (2016). Hip kinematics and kinetics in persons with and without cam femoroacetabular impingement during a deep squat task. Clin Biomech (Bristol, Avon), 31, 87–92. 10.1016/j.clinbiomech.2015.09.016 [DOI] [PubMed] [Google Scholar]
  3. Bergmann G, Deuretzbacher G, Heller M, Graichen F, Rohlmann A, Strauss J, & Duda GN. (2001). Hip contact forces and gait patterns from routine activities. J Biomech, 34(7), 859–871. 10.1016/s0021-9290(01)00040-9 [DOI] [PubMed] [Google Scholar]
  4. Brisson N, Lamontagne M, Kennedy MJ, & Beaule PE. (2013). The effects of cam femoroacetabular impingement corrective surgery on lower-extremity gait biomechanics. Gait Posture, 37(2), 258–263. 10.1016/j.gaitpost.2012.07.016 [DOI] [PubMed] [Google Scholar]
  5. Casartelli NC, Maffiuletti NA, Item-Glatthorn JF, Staehli S, Bizzini M, Impellizzeri FM, & Leunig M. (2011). Hip muscle weakness in patients with symptomatic femoroacetabular impingement. Osteoarthritis Cartilage, 19(7), 816–821. 10.1016/j.joca.2011.04.001 [DOI] [PubMed] [Google Scholar]
  6. Cheng AL, Radlicz CM, Pashos MM, Huecker JB, Steger-May K, Prather H, Clohisy JC, & Harris-Hayes M. (2025). Defining the Minimal Clinically Important Improvement, Substantial Clinical Benefit, and Patient Acceptable Symptom State for the iHOT-12, HOOS, and HOOS(global) in the Nonoperative Management of Nonarthritic Hip-Related Pain. Am J Sports Med, 53(6), 1486–1493. 10.1177/03635465251325466 [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Cohen J, 1988. Statistical Power Analysis for the Behavioral Sciences, Second ed. Lawrence Erlbaum Associates, Publishers, New York, New York. [Google Scholar]
  8. Crossley KM, Lin YC, Schache AG, Smith AJ, King MG, Heerey JJ, Agricola R, Sharmila M, Souza RB, Link TM, Mentiplay BF, Scholes MJ, Semciw AI, Lawrenson PR, Kemp JL, & Pandy MG. (2026). Hip Joint Loading During Walking Is Associated With Cartilage Defect Severity in Young Adult Football Players With Hip/Groin Pain. J Orthop Res, 44(5), e70219. 10.1002/jor.70219 [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Cvetanovich GL, Farkas GJ, Beck EC, Malloy P, Jan K, Espinoza-Orias A, & Nho SJ. (2020). Squat and gait biomechanics 6 months following hip arthroscopy for femoroacetabular impingement syndrome. J Hip Preserv Surg, 7(1), 27–37. 10.1093/jhps/hnaa004 [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Diamond LE, Bennell KL, Wrigley TV, Hinman RS, O’Donnell J, & Hodges PW. (2017). Squatting Biomechanics in Individuals with Symptomatic Femoroacetabular Impingement. Med Sci Sports Exerc, 49(8), 1520–1529. 10.1249/MSS.0000000000001282 [DOI] [PubMed] [Google Scholar]
  11. Diamond LE, Wrigley TV, Bennell KL, Hinman RS, O’Donnell J, & Hodges PW. (2016). Hip joint biomechanics during gait in people with and without symptomatic femoroacetabular impingement. Gait Posture, 43, 198–203. 10.1016/j.gaitpost.2015.09.023 [DOI] [PubMed] [Google Scholar]
  12. Enseki KR, Bloom NJ, Harris-Hayes M, Cibulka MT, Disantis A, Di Stasi S, Malloy P, Clohisy JC, & Martin RL. (2023). Hip Pain and Movement Dysfunction Associated With Nonarthritic Hip Joint Pain: A Revision. J Orthop Sports Phys Ther, 53(7), CPG1–CPG70. 10.2519/jospt.2023.0302 [DOI] [PubMed] [Google Scholar]
  13. Frasson VB, Vaz MA, Morales AB, Torresan A, Teloken MA, Gusmao PDF, Crestani MV, & Baroni BM. (2020). Hip muscle weakness and reduced joint range of motion in patients with femoroacetabular impingement syndrome: a case-control study. Braz J Phys Ther, 24(1), 39–45. 10.1016/j.bjpt.2018.11.010 [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Griffin DR, Dickenson EJ, O’Donnell J, Agricola R, Awan T, Beck M, Clohisy JC, Dijkstra HP, Falvey E, Gimpel M, Hinman RS, Holmich P, Kassarjian A, Martin HD, Martin R, Mather RC, Philippon MJ, Reiman MP, Takla A,…Bennell K. (2016). The Warwick Agreement on femoroacetabular impingement syndrome (FAI syndrome): an international consensus statement. Br J Sports Med, 50(19), 1169–1176. 10.1136/bjsports-2016-096743 [DOI] [PubMed] [Google Scholar]
  15. Griffin DR, Parsons N, Mohtadi NG, Safran MR, & Multicenter Arthroscopy of the Hip Outcomes Research, N. (2012). A short version of the International Hip Outcome Tool (iHOT-12) for use in routine clinical practice. Arthroscopy, 28(5), 611–616; quiz 616–618. 10.1016/j.arthro.2012.02.027 [DOI] [PubMed] [Google Scholar]
  16. Griffin TM, & Guilak F. (2005). The role of mechanical loading in the onset and progression of osteoarthritis. Exerc Sport Sci Rev, 33(4), 195–200. 10.1097/00003677-200510000-00008 [DOI] [PubMed] [Google Scholar]
  17. Grimmer M, Zeiss J, Weigand F, & Zhao G. (2023). Joint power, joint work and lower limb muscle activity for transitions between level walking and stair ambulation at three inclinations. PLoS One, 18(11), e0294161. 10.1371/journal.pone.0294161 [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Harris-Hayes M, Czuppon S, Van Dillen LR, Steger-May K, Sahrmann S, Schootman M, Salsich GB, Clohisy JC, & Mueller MJ. (2016). Movement-Pattern Training to Improve Function in People With Chronic Hip Joint Pain: A Feasibility Randomized Clinical Trial. J Orthop Sports Phys Ther, 46(6), 452–461. 10.2519/jospt.2016.6279 [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Harris-Hayes M, Hillen TJ, Commean PK, Harris MD, Mueller MJ, Clohisy JC, & Salsich GB. (2020). Hip Kinematics During Single-Leg Tasks in People With and Without Hip-Related Groin Pain and the Association Among Kinematics, Hip Muscle Strength, and Bony Morphology. J Orthop Sports Phys Ther, 50(5), 243–251. 10.2519/jospt.2020.9150 [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Harris-Hayes M, Steger-May K, A MB, Mueller MJ, Clohisy JC, & Fitzgerald GK. (2021). One-year outcomes following physical therapist-led intervention for chronic hip-related groin pain: Ancillary analysis of a pilot multicenter randomized clinical trial. J Orthop Res, 39(11), 2409–2418. 10.1002/jor.24985 [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Hoit G, Whelan DB, Dwyer T, Ajrawat P, & Chahal J. (2020). Physiotherapy as an Initial Treatment Option for Femoroacetabular Impingement: A Systematic Review of the Literature and Meta-analysis of 5 Randomized Controlled Trials. Am J Sports Med, 48(8), 2042–2050. 10.1177/0363546519882668 [DOI] [PubMed] [Google Scholar]
  22. Hunt MA, Guenther JR, & Gilbart MK. (2013). Kinematic and kinetic differences during walking in patients with and without symptomatic femoroacetabular impingement. Clin Biomech (Bristol, Avon), 28(5), 519–523. 10.1016/j.clinbiomech.2013.05.002 [DOI] [PubMed] [Google Scholar]
  23. Ishoi L, Nielsen MF, Krommes K, Husted RS, Holmich P, Pedersen LL, & Thorborg K. (2021). Femoroacetabular impingement syndrome and labral injuries: grading the evidence on diagnosis and non-operative treatment-a statement paper commissioned by the Danish Society of Sports Physical Therapy (DSSF). Br J Sports Med, 55(22), 1301–1310. 10.1136/bjsports-2021-104060 [DOI] [PubMed] [Google Scholar]
  24. Kannan AS, Hartwell MJ, Grace T, Hammond E, Soriano KKJ, Souza RB, & Zhang AL. (2022). Correlating Biomechanical Gait Analysis With Patient-Reported Outcomes After Hip Arthroscopy for Femoroacetabular Impingement Syndrome. Orthop J Sports Med, 10(9), 23259671221121352. 10.1177/23259671221121352 [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Kemp JL, Coburn SL, Jones DM, & Crossley KM. (2018). The Physiotherapy for Femoroacetabular Impingement Rehabilitation STudy (physioFIRST): A Pilot Randomized Controlled Trial. J Orthop Sports Phys Ther, 48(4), 307–315. 10.2519/jospt.2018.7941 [DOI] [PubMed] [Google Scholar]
  26. Kemp JL, Makdissi M, Schache AG, Pritchard MG, Pollard TC, & Crossley KM. (2014). Hip chondropathy at arthroscopy: prevalence and relationship to labral pathology, femoroacetabular impingement and patient-reported outcomes. Br J Sports Med, 48(14), 1102–1107. 10.1136/bjsports-2013-093312 [DOI] [PubMed] [Google Scholar]
  27. Kennedy MJ, Lamontagne M, & Beaule PE. (2009). Femoroacetabular impingement alters hip and pelvic biomechanics during gait Walking biomechanics of FAI. Gait Posture, 30(1), 41–44. 10.1016/j.gaitpost.2009.02.008 [DOI] [PubMed] [Google Scholar]
  28. Kierkegaard S, Langeskov-Christensen M, Lund B, Naal FD, Mechlenburg I, Dalgas U, & Casartelli NC. (2017). Pain, activities of daily living and sport function at different time points after hip arthroscopy in patients with femoroacetabular impingement: a systematic review with meta-analysis. Br J Sports Med, 51(7), 572–579. 10.1136/bjsports-2016-096618 [DOI] [PubMed] [Google Scholar]
  29. Kierkegaard S, Mechlenburg I, Lund B, Soballe K, & Dalgas U. (2017). Impaired hip muscle strength in patients with femoroacetabular impingement syndrome. J Sci Med Sport, 20(12), 1062–1067. 10.1016/j.jsams.2017.05.008 [DOI] [PubMed] [Google Scholar]
  30. King MG, Heerey JJ, Schache AG, Semciw AI, Middleton KJ, Sritharan P, Lawrenson PR, & Crossley KM. (2019). Lower limb biomechanics during low- and high-impact functional tasks differ between men and women with hip-related groin pain. Clin Biomech (Bristol), 68, 96–103. 10.1016/j.clinbiomech.2019.06.001 [DOI] [PubMed] [Google Scholar]
  31. King MG, Schache AG, Semciw AI, Middleton KJ, Heerey JJ, Kemp JL, Sritharan P, Scholes MJ, Mentiplay BF, & Crossley KM. (2021). Lower-limb work during high- and low-impact activities in hip-related pain: Associations with sex and symptom severity. Gait Posture, 83, 1–8. 10.1016/j.gaitpost.2020.09.025 [DOI] [PubMed] [Google Scholar]
  32. Kumar D, Dillon A, Nardo L, Link TM, Majumdar S, & Souza RB. (2014). Differences in the association of hip cartilage lesions and cam-type femoroacetabular impingement with movement patterns: a preliminary study. PM R, 6(8), 681–689. 10.1016/j.pmrj.2014.02.002 [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Lamontagne M, Kennedy MJ, & Beaule PE. (2009). The effect of cam FAI on hip and pelvic motion during maximum squat. Clin Orthop Relat Res, 467(3), 645–650. 10.1007/s11999-008-0620-x [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Lunn DE, Chapman GJ, & Redmond AC. (2019). Hip kinematics and kinetics in total hip replacement patients stratified by age and functional capacity. J Biomech, 87, 19–27. 10.1016/j.jbiomech.2019.02.002 [DOI] [PubMed] [Google Scholar]
  35. Lutz AB, Ventimiglia DJ, Honig EL, McCurdy MA, Hartline JT, O’Hara NN, Henn RF 3rd, & Meredith SJ. (2026). Trajectory and rate of recovery of function, pain and activity level after hip arthroscopy. Hip Int, 11207000251395633. 10.1177/11207000251395633 [DOI] [PubMed] [Google Scholar]
  36. Malloy P, Neumann DA, & Kipp K. (2019). Hip Biomechanics During a Single-Leg Squat: 5 Key Differences Between People With Femoroacetabular Impingement Syndrome and Those Without Hip Pain. J Orthop Sports Phys Ther, 49(12), 908–916. 10.2519/jospt.2019.8356 [DOI] [PubMed] [Google Scholar]
  37. Malloy P, Wichman DM, Garcia F, Espinoza-Orias A, Chahla J, & Nho SJ. (2021). Impaired Lower Extremity Biomechanics, Hip External Rotation Muscle Weakness, and Proximal Femoral Morphology Predict Impaired Single-Leg Squat Performance in People With FAI Syndrome. Am J Sports Med, 49(11), 2984–2993. 10.1177/03635465211029032 [DOI] [PubMed] [Google Scholar]
  38. Meyer CAG, Wesseling M, Corten K, Nieuwenhuys A, Monari D, Simon JP, Jonkers I, & Desloovere K. (2018). Hip movement pathomechanics of patients with hip osteoarthritis aim at reducing hip joint loading on the osteoarthritic side. Gait Posture, 59, 11–17. 10.1016/j.gaitpost.2017.09.020 [DOI] [PubMed] [Google Scholar]
  39. Mortensen L, Schultz J, Elsner A, Jakobsen SS, Soballe K, Jacobsen JS, Kierkegaard S, Dalgas U, & Mechlenburg I. (2018). Progressive resistance training in patients with hip dysplasia: A feasibility study. J Rehabil Med, 50(8), 751–758. 10.2340/16501977-2371 [DOI] [PubMed] [Google Scholar]
  40. Negahban H, Mostafaee N, Sohani SM, Mazaheri M, Goharpey S, Salavati M, Zahednejad S, Meshkati Z, & Montazeri A. (2011). Reliability and validity of the Tegner and Marx activity rating scales in Iranian patients with anterior cruciate ligament injury. Disabil Rehabil, 33(23–24), 2305–2310. 10.3109/09638288.2011.570409 [DOI] [PubMed] [Google Scholar]
  41. Nepple JJ, Goljan P, Briggs KK, Garvey SE, Ryan M, & Philippon MJ. (2015). Hip Strength Deficits in Patients With Symptomatic Femoroacetabular Impingement and Labral Tears. Arthroscopy, 31(11), 2106–2111. 10.1016/j.arthro.2015.04.095 [DOI] [PubMed] [Google Scholar]
  42. Probst DT, Sookochoff MF, Harris-Hayes M, Prather H, Lipsey KL, & Cheng AL. (2023). What is the Rate of Response to Nonoperative Treatment for Hip-Related Pain? A Systematic Review With Meta-analysis. J Orthop Sports Phys Ther, 53(5), 286–306. 10.2519/jospt.2023.11666 [DOI] [PMC free article] [PubMed] [Google Scholar]
  43. Queen RM, Campbell JC, & Schmitt D. (2019). Gait Analysis Reveals that Total Hip Arthroplasty Increases Power Production in the Hip During Level Walking and Stair Climbing. Clin Orthop Relat Res, 477(8), 1839–1847. 10.1097/CORR.0000000000000809 [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Reiman MP, Agricola R, Kemp JL, Heerey JJ, Weir A, van Klij P, Kassarjian A, Mosler AB, Ageberg E, Holmich P, Warholm KM, Griffin D, Mayes S, Khan KM, Crossley KM, Bizzini M, Bloom N, Casartelli NC, Diamond LE,…Dijkstra HP. (2020). Consensus recommendations on the classification, definition and diagnostic criteria of hip-related pain in young and middle-aged active adults from the International Hip-related Pain Research Network, Zurich 2018. Br J Sports Med, 54(11), 631–641. 10.1136/bjsports-2019-101453 [DOI] [PubMed] [Google Scholar]
  45. Rylander JH, Shu B, Andriacchi TP, & Safran MR. (2011). Preoperative and postoperative sagittal plane hip kinematics in patients with femoroacetabular impingement during level walking. Am J Sports Med, 39 Suppl, 36S–42S. 10.1177/0363546511413993 [DOI] [PubMed] [Google Scholar]
  46. Samaan MA, Grace T, Zhang AL, Majumdar S, & Souza RB. (2020). Short term outcomes of hip arthroscopy on hip joint mechanics and cartilage health in patients with femoroacetabular impingement syndrome. Clin Biomech (Bristol), 71, 214–220. 10.1016/j.clinbiomech.2019.11.014 [DOI] [PMC free article] [PubMed] [Google Scholar]
  47. Samaan MA, Schwaiger BJ, Gallo MC, Sada K, Link TM, Zhang AL, Majumdar S, & Souza RB. (2017). Joint Loading in the Sagittal Plane During Gait Is Associated With Hip Joint Abnormalities in Patients With Femoroacetabular Impingement. Am J Sports Med, 45(4), 810–818. 10.1177/0363546516677727 [DOI] [PMC free article] [PubMed] [Google Scholar]
  48. Scholes MJ, King MG, Crossley KM, Jones DM, Semciw AI, Mentiplay BF, Heerey JJ, Lawrenson PR, Coburn SL, Johnston RTR, Bell EC, Girdwood M, & Kemp JL. (2021). The Validity, Reliability, and Responsiveness of the International Hip Outcome Tool-33 (iHOT-33) in Patients With Hip and Groin Pain Treated Without Surgery. Am J Sports Med, 49(10), 2677–2688. 10.1177/03635465211027180 [DOI] [PubMed] [Google Scholar]
  49. Stanze HM, Wilcox BJ, Mangino AA, Samaan MA, & Jochimsen KN. (2025). Hip-related symptom duration is associated with alterations in hip mechanics during a single leg squat. Clin Biomech (Bristol), 128, 106630. 10.1016/j.clinbiomech.2025.106630 [DOI] [PMC free article] [PubMed] [Google Scholar]
  50. Swindell H, Wichman DM, Guidetti M, Chahla J, Nho SJ, & Malloy P. (2023). Association of Changes in Hip and Knee Kinematics During a Single-Leg Squat With Changes in Patient-Reported Outcomes at 6 Months and 1 Year After Hip Arthroscopy. Am J Sports Med, 51(13), 3439–3446. 10.1177/03635465231202025 [DOI] [PubMed] [Google Scholar]
  51. Thorborg K, Tijssen M, Habets B, Bartels EM, Roos EM, Kemp J, Crossley KM, & Holmich P. (2015). Patient-Reported Outcome (PRO) questionnaires for young to middle-aged adults with hip and groin disability: a systematic review of the clinimetric evidence. Br J Sports Med, 49(12), 812. 10.1136/bjsports-2014-094224 [DOI] [PubMed] [Google Scholar]
  52. Wade F, Huang CH, & Foucher KC. (2025). Individual joint contributions to forward propulsion during treadmill walking in women with hip osteoarthritis. J Orthop Res, 43(1), 94–101. 10.1002/jor.25964 [DOI] [PMC free article] [PubMed] [Google Scholar]
  53. Weir A, Brukner P, Delahunt E, Ekstrand J, Griffin D, Khan KM, Lovell G, Meyers WC, Muschaweck U, Orchard J, Paajanen H, Philippon M, Reboul G, Robinson P, Schache AG, Schilders E, Serner A, Silvers H, Thorborg K,…Holmich P. (2015). Doha agreement meeting on terminology and definitions in groin pain in athletes. Br J Sports Med, 49(12), 768–774. 10.1136/bjsports-2015-094869 [DOI] [PMC free article] [PubMed] [Google Scholar]
  54. Winter DA. (1979). Biomechanics of human movement. Wiley. [Google Scholar]
  55. Young JJ, Skou ST, Koes BW, Gronne DT, & Roos EM. (2020). Proportion of patients with hip osteoarthritis in primary care identified by differing clinical criteria: a cross-sectional study of 4699 patients. Osteoarthr Cartil Open, 2(4), 100111. 10.1016/j.ocarto.2020.100111 [DOI] [PMC free article] [PubMed] [Google Scholar]
  56. Zajac FE, Neptune RR, & Kautz SA. (2002). Biomechanics and muscle coordination of human walking. Part I: introduction to concepts, power transfer, dynamics and simulations. Gait Posture, 16(3), 215–232. 10.1016/s0966-6362(02)00068-1 [DOI] [PubMed] [Google Scholar]

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