Relationship between hip and core strength and frontal plane alignment during a single leg squat

Phys Ther Sport. 2015 Feb;16(1):66-71. doi: 10.1016/j.ptsp.2014.05.002. Epub 2014 Jun 3.


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 r(2) = 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.

Keywords: Mechanics; Patellofemoral pain syndrome; Single leg squat.

MeSH terms

  • Adolescent
  • Adult
  • Biomechanical Phenomena
  • Exercise Test*
  • Female
  • Hip / anatomy & histology
  • Hip / physiology*
  • Humans
  • Leg / physiology*
  • Muscle Strength*
  • Muscle, Skeletal / physiology*
  • Patellofemoral Pain Syndrome
  • Posture / physiology
  • Young Adult