Changes in knee biomechanics after a hip-abductor strengthening protocol for runners with patellofemoral pain syndrome

J Athl Train. 2011 Mar-Apr;46(2):142-9. doi: 10.4085/1062-6050-46.2.142.


Context: Very few authors have investigated the relationship between hip-abductor muscle strength and frontal-plane knee mechanics during running.

Objective: To investigate this relationship using a 3-week hip-abductor muscle-strengthening program to identify changes in strength, pain, and biomechanics in runners with patellofemoral pain syndrome (PFPS).

Design: Cohort study.

Setting: University-based clinical research laboratory.

Patients or other participants: Fifteen individuals (5 men, 10 women) with PFPS and 10 individuals without PFPS (4 men, 6 women) participated.

Intervention(s): The patients with PFPS completed a 3-week hip-abductor strengthening protocol; control participants did not.

Main outcome measure(s): The dependent variables of interest were maximal isometric hip-abductor muscle strength, 2-dimensional peak knee genu valgum angle, and stride-to-stride knee-joint variability. All measures were recorded at baseline and 3 weeks later. Between-groups differences were compared using repeated-measures analyses of variance.

Results: At baseline, the PFPS group exhibited reduced strength, no difference in peak genu valgum angle, and increased stride-to-stride knee-joint variability compared with the control group. After the 3-week protocol, the PFPS group demonstrated increased strength, less pain, no change in peak genu valgum angle, and reduced stride-to-stride knee-joint variability compared with baseline.

Conclusions: A 3-week hip-abductor muscle-strengthening protocol was effective in increasing muscle strength and decreasing pain and stride-to-stride knee-joint variability in individuals with PFPS. However, concomitant changes in peak knee genu valgum angle were not observed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Athletes*
  • Biomechanical Phenomena
  • Female
  • Hip / physiology*
  • Humans
  • Knee / physiology*
  • Knee Joint / physiology*
  • Male
  • Muscle Strength*
  • Muscle, Skeletal / physiology
  • Muscles / physiology
  • Pain Measurement
  • Patellofemoral Pain Syndrome / therapy*
  • Range of Motion, Articular / physiology
  • Rehabilitation
  • Resistance Training / methods*
  • Running