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Effectiveness of Core Muscle Strengthening for Reducing Pain and Improving Balance in Females with Patellofemoral Pain Syndrome

Tuesday, June 6, 2023 - 0 Likes

Brent Brookbush

Brent Brookbush


Research Review: Effectiveness of Core Muscle Strengthening for Reducing Pain and Improving Balance in Females with Patellofemoral Pain Syndrome

By Tristan J. Rodik, M.AT., ATC

Edited By Brent Brookbush, DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Chevidikunnan, M. F., Saif, A. A., Gaowgzeh, R. A., and Mamdouh, K. A. (2016) Effectiveness of core muscle strengthening for improving pain and dynamic balance among female patients with patellofemoral pain syndrome. Journal of Physical Therapy Science, 28, 1518-1523. FULL ARTICLE

Introduction: Studies have shown the gluteus maximus and gluteus medius (gluteal complex ) strengthening is an effective addition to treatment for patellofemoral pain syndrome (PFPS) (1-15). Research also demonstrates, adding core strengthening (rectus abdominis , external obliques , and paraspinals ) to gluteal complex strengthening may provide additional benefits (13, 15). This 2016 study by Saudi Arabian researchers demonstrates that core strengthening combined with conventional physical therapy (general hip and knee strengthening program) can reduce pain and improve balance in females with PFPS. This study reinforces the positive impact core exercise has on outcomes for this dysfunction.

Dynamic Quadruped
Caption: Dynamic Quadruped

Study Summary

Study Design  Experimental study
Level of Evidence IIB Evidence from at least one other type of quasi-experimental study
Participant Characteristics


Control Group: Conventional Physical Therapy

  • Age: 22.2 +/- 1.3
  • Height: 158.7 +/- 5.1 cm
  • Body Weight: 64.8 +/- 8.4 kg
  • Gender: Female
  • Number of participants: 10

Experimental Group: Core Strengthening Physical Therapy

  • Age: 21.4 +/- 1.8
  • Height: 160.3 +/- 4.6 cm
  • Body Weight: 68.3 +/- 7.7 kg
  • Gender: Female
  • Number of Participants: 10

Inclusion Criteria:

  • Female
  • Age 16-40
  • Anterior knee pain for at least 4 weeks
  • Knee pain aggravated by at least 2 of the following activities:
    • jumping
    • running
    • prolonged sitting
    • stair climbing
    • kneeling
    • squatting

  • A positive patellar grind test
  • Physically active for at least 30 minutes per day on most days of the week
  • Average Visual Analog Scale (VAS) of 3/10
  • Insidious onset of symptoms
  • Knee pain not related to trauma

Exclusion Criteria:

  • Cruciate or collateral ligament injuries
  • Meniscal injuries
  • Any intra-articular injury
  • Tenderness to palpation of the following areas:

  • Joint effusion
  • Referred pain from the hip or lumbar region
  • Known case of articular cartilage damage
  • Surgical history of the knee
  • Spinal or lower-extremity deformity
  • Long-term use of non-steroidal anti-inflammatory drug or corticosteroid medication
  • Pregnancy
  • Sports training
    • Specific sport participation for at least 2 hours/day and 3x/week

  • Participants were randomly assigned to one of two groups:
    • Core strengthening with conventional physical therapy (experimental group)
    • Convention physical therapy (control group)

  • Exercises were performed 3x/week for 4 weeks
  • The visual analog scale (VAS) pain score and Star Excursion Balance Test (SEBT) were completed before and after the intervention period

Experimental Group

  • Core strengthening exercises were performed with conventional physical therapy 3x/week for 4 weeks.
  • Each session lasted approximately 30-45 minutes and consisted of a warm-up, physical therapy and a cool-down phase.
  • Core strengthening exercises consisted of the following:

  • Training intensity progressively increased by altering lever arms and increasing repetitions of the core strengthening exercises.
  • Rest periods lasted 2-3 minutes between each exercise.

Control Group

Data Collection and Analysis
  • Data were statistically analyzed with SPSS for Windows (version 19.0; SPSS Inc., Chicago, IL, USA)
  • Descriptive statistics included the mean, standard deviation and 95% confidence interval
  • Paired t-tests were used to compare balance variables before and after the intervention
  • VAS results were compared by using the non-parametric Mann-Whitney U test
Outcome Measures
  • Visual Analog Scale score
  • Star Excursion Balance Test
Results Visual Analog Scale (VAS)
  • Mean VAS prior to intervention was 6.5 for the control group and 6.3 for the experimental group
  • Mean VAS after the intervention was 2.3 for the control group and 1.2 for the experimental group
  • Only the experimental group noted a significant reduction in VAS after the intervention (p <0.05)

Star Excursion Balance Test (SEBT)

  • Mean SEBT scores prior to intervention were 56.3cm for the control group and 58.1cm for the experimental group
  • Mean SEBT scores after the intervention were 68.7cm for the control group and 78.1cm for the experimental group
  • Only the experimental group noted a significant improvement in SEBT scores after the intervention (p < 0.05)
Our Conclusions This study demonstrates that core, gluteal complex, and quadriceps strengthening improves self-reported pain and dynamic balance in females with PFPS. Further, the addition of core exercise may provide additional benefits to conventional hip and knee strengthening programs. These findings are congruent with the Brookbush Institute’s integrated approach, which includes gluteal complex and core activation for individuals with Lower Extremity Dysfunction (LED), including those with symptoms of PFPS.
Researchers' Conclusions

The results of this study offer an approach for addressing PFPS. The findings demonstrate that combining core muscle strengthening and conventional physical therapy helps reduce pain intensity and improve dynamic balance in females with PFPS.

Ultimate Glute Bridge

How This Study Contributes to the Body of Research:

A decrease in core reactivity and less glute complex strength have been correlated with increased risk of knee injury (16, 17). This study compared a conventional program (hip and knee strengthening) to the same program with additional core strengthening for the treatment of PFPS (5, 6, 10, 11, 13, 15). Further, this study added balance as an outcome measure, using the STAR excursion balance. The outcomes suggest that the addition of core strengthening to a conventional 4-week can program can significantly improve self-reported pain as well as balance parameters.

How the Findings Apply to Practice:

The study demonstrates a relationship between the intent to increase core muscle strength, endurance, and/or stability, and the resolution of symptoms of patellofemoral pain syndrome (PFPS). Human movement professionals should consider integrating core exercise into PFPS programs. Further, although little research exists to support the reliability of core assessments, assessing the core, adding the STAR excursion balance test, and/or monitoring improvements made during core exercises should be considered.

This study had many methodological strengths, including:

  1. The exercises and balance assessments used in the study required minimal equipment, allowing human movement professionals to easily incorporate them into practice.
  2. Researchers were blinded to participants’ group allocation, enhancing the validity of the results.
  3. Methods for the core strengthening exercises were clearly described, enhancing clinical applicability.
  4. Comparing the addition of core exercise to a well thought-out program, added to the clinical significance of the study.

Weaknesses that should be noted prior to clinical integration:

  1. A female-only cohort limits the generalizability of the study.
  2. The lack of electromyography (EMG) and manual muscle testing makes comparison to other studies on this topic difficult.
  3. The lack of follow-up results in questions regarding the efficacy of the addition of core exercise for reducing PFPS long-term.

How this Study Relates to Brookbush Institute Content:

The positive outcomes demonstrated with the addition of core exercise to gluteal complex and quadricep strengthening for self-reported pain and dynamic balance in females with PFPS supports several assertions/assumptions made in the Brookbush Institutes' (BI) predictive models of Lower Extremity Dysfunction (LED) , Lumbopelvic Hip Complex Dysfunction (LPHCD) and Sacroiliac Joint Dysfunction (SIJD) . This includes assertions about regional interdependence, the benefits of integrated practice, the benefits of core stability exercise, and the effect integrated practice can have on performance outcomes like balance. The program used in the experimental group of this study more closely resembled a BI corrective intervention; however, the BI recommends starting all programs with appropriate mobility techniques.

The following videos illustrate exercise techniques for core strengthening:

Sample Videos Related to the Research Content:

Quadruped with Glute Activation

Standing Chop Pattern

The Ultimate Glute Bridge

Recommended Readings:

  1. Panel Discussion: Increasing glute activity, recruitment, endurance and strength.
  2. Panel Discussion: Core function and performance.


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© 2018 Brent Brookbush

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