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Influence of step height on quadriceps onset timing and activation during stair ascent in individuals with patellofemoral pain syndrome.
J Orthop Sports Phys Ther. 2007 May; 37(5):239-44.JO

Abstract

STUDY DESIGN

A case control study, with single observation.

OBJECTIVES

To compare the onset timing and activation of the vastus medialis oblique (VMO) and vastus lateralis (VL) between subjects with and without patellofemoral pain syndrome (PFPS) at various step heights.

BACKGROUND

It has been theorized that delayed or reduced VMO activity relative to the VL contributes to lateral patellar tracking and PFPS. However, conflicting evidence exists in the literature regarding this proposed mechanism. The lack of agreement among studies may be attributed to inconsistent knee flexion angles used in previous studies.

METHODS AND MEASURES

Twenty subjects with PFPS (mean +/- SD age, 29.5 +/- 10 years) and 20 control subjects (mean +/- SD age, 25.4 +/- 3.1 years) ascended 5 different step heights, while knee kinematics and quadriceps EMG data were collected. Knee flexion angle at foot-step contact, VMO-VL onset timing, and VMO/VL activation ratios were analyzed between groups and step heights using 2-factor analyses of variance (ANOVAs) with repeated measures (alpha = .05).

RESULTS

Individuals with PFPS demonstrated 4.7 degrees (P = .038) more knee flexion at foot-step contact than control subjects. Despite greater knee flexion with increased step height (P<.001), no differences in onset timing or activation magnitude ratio were present between groups or across step heights. However, individuals with PFPS displayed a significantly increased activation duration ratio compared to the control group (P = .043).

CONCLUSION

Quadriceps onset timing and activation magnitude during stair ascent was similar between individuals with and without PFPS, regardless of step height. Thus, the results of this study are in agreement with evidence indicating no difference in VMO-VL timing and VMO/VL activation magnitude ratio between individuals with and without PFPS.

Authors+Show Affiliations

Physical Therapist, Des Moines University-Osteopathic Medical Center, Des Moines, IA, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17549952

Citation

McClinton, Shane, et al. "Influence of Step Height On Quadriceps Onset Timing and Activation During Stair Ascent in Individuals With Patellofemoral Pain Syndrome." The Journal of Orthopaedic and Sports Physical Therapy, vol. 37, no. 5, 2007, pp. 239-44.
McClinton S, Donatell G, Weir J, et al. Influence of step height on quadriceps onset timing and activation during stair ascent in individuals with patellofemoral pain syndrome. J Orthop Sports Phys Ther. 2007;37(5):239-44.
McClinton, S., Donatell, G., Weir, J., & Heiderscheit, B. (2007). Influence of step height on quadriceps onset timing and activation during stair ascent in individuals with patellofemoral pain syndrome. The Journal of Orthopaedic and Sports Physical Therapy, 37(5), 239-44.
McClinton S, et al. Influence of Step Height On Quadriceps Onset Timing and Activation During Stair Ascent in Individuals With Patellofemoral Pain Syndrome. J Orthop Sports Phys Ther. 2007;37(5):239-44. PubMed PMID: 17549952.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Influence of step height on quadriceps onset timing and activation during stair ascent in individuals with patellofemoral pain syndrome. AU - McClinton,Shane, AU - Donatell,Gabe, AU - Weir,Joseph, AU - Heiderscheit,Bryan, PY - 2007/6/7/pubmed PY - 2007/7/20/medline PY - 2007/6/7/entrez SP - 239 EP - 44 JF - The Journal of orthopaedic and sports physical therapy JO - J Orthop Sports Phys Ther VL - 37 IS - 5 N2 - STUDY DESIGN: A case control study, with single observation. OBJECTIVES: To compare the onset timing and activation of the vastus medialis oblique (VMO) and vastus lateralis (VL) between subjects with and without patellofemoral pain syndrome (PFPS) at various step heights. BACKGROUND: It has been theorized that delayed or reduced VMO activity relative to the VL contributes to lateral patellar tracking and PFPS. However, conflicting evidence exists in the literature regarding this proposed mechanism. The lack of agreement among studies may be attributed to inconsistent knee flexion angles used in previous studies. METHODS AND MEASURES: Twenty subjects with PFPS (mean +/- SD age, 29.5 +/- 10 years) and 20 control subjects (mean +/- SD age, 25.4 +/- 3.1 years) ascended 5 different step heights, while knee kinematics and quadriceps EMG data were collected. Knee flexion angle at foot-step contact, VMO-VL onset timing, and VMO/VL activation ratios were analyzed between groups and step heights using 2-factor analyses of variance (ANOVAs) with repeated measures (alpha = .05). RESULTS: Individuals with PFPS demonstrated 4.7 degrees (P = .038) more knee flexion at foot-step contact than control subjects. Despite greater knee flexion with increased step height (P<.001), no differences in onset timing or activation magnitude ratio were present between groups or across step heights. However, individuals with PFPS displayed a significantly increased activation duration ratio compared to the control group (P = .043). CONCLUSION: Quadriceps onset timing and activation magnitude during stair ascent was similar between individuals with and without PFPS, regardless of step height. Thus, the results of this study are in agreement with evidence indicating no difference in VMO-VL timing and VMO/VL activation magnitude ratio between individuals with and without PFPS. SN - 0190-6011 UR - https://www.unboundmedicine.com/medline/citation/17549952/Influence_of_step_height_on_quadriceps_onset_timing_and_activation_during_stair_ascent_in_individuals_with_patellofemoral_pain_syndrome_ L2 - https://www.jospt.org/doi/10.2519/jospt.2007.2421?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -