Background: The wall squat is considered an effective exercise because it can reduce the knee load and prevent excessive lumbar movement. However, the relationship between wall squat performance and strength of knee extensors and hip extensors remained unclear. Objects: The purpose of this study was to compare the strengths of the knee extensors and hip extensors between groups with low and high wall squat performance. Method: Nineteen males (low performance group: 9 subjects, high performance group: 10 subjects) participated in this study and performed wall squats. The subjects who were performing less than 30% of the average wall squat count were classified into the low wall squat performance group (less than or equal to 4 times) and the subjects who performed more than 30% of the average wall squat count were classified into the high wall squat performance group (greater than or equal to 8 times). Knee extensor and hip extensor strength were measured with a strength measurement system. An independent t-test was used to compare the strengths of the knee extensors and hip extensors between the groups with low and high wall squat performance. Results: The ratios of knee extensor and hip extensor strength to bodyweight were greater in the high wall squat performance group than in the low wall squat performance group (knee extensors: p<.001; hip extensors: p=.03). In the high- and low-performance groups, the ratios of knee extensor strength to bodyweight were 42.74±5.72 and 30.76±8.54, respectively, and the ratios of hip extensor strength to bodyweight were 31.95±10.61 and 20.66±11.25, respectively. Conclusion: Our findings suggest that knee extensor and hip extensor strength are needed for high wall squat performance. Thus, exercise to increase the knee and hip extensors strength can be recommended to improve squat performance.

Abstract
 Introduction
 Methods
  Subjects
  Wall squat
  Strength measure
  Statistical analysis
 Results
 Discussion
 Conclusion
 References

• Sung-hoon Jung(Kinetic Ergocise Based on Movement Analysis Laboratory, Dept. of Physical Therapy, The Graduate School, Yonsei University)
• Moon-hwan Kim(Kinetic Ergocise Based on Movement Analysis Laboratory, Dept. of Rehabilitation Medicine, Wonju Severance Christian Hospital)
• Ui-jae Hwang(Kinetic Ergocise Based on Movement Analysis Laboratory, Dept. of Physical Therapy, The Graduate School, Yonsei University)
• Jun-hee Kim(Kinetic Ergocise Based on Movement Analysis Laboratory, Dept. of Physical Therapy, The Graduate School, Yonsei University)
• Oh-yun Kwon(Kinetic Ergocise Based on Movement Analysis Laboratory, Dept. of Physical Therapy, College of Health Science, Yonsei University, Dept. of Ergonomic Therapy, The Graduate School of Health and Environment, Yonsei University) Corresponding author