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Effect of hip position on gravity effect torque
W J Ford1, S D Bailey, K Babich
1Krannert Graduate School of Physical Therapy, University of Indianapolis, IN 46277.
Medicine and Science in Sports and Exercise
|February 1, 1994
Summary
The seated position results in higher gravity effect torque (GET) than the supine position during knee isokinetic testing. This difference impacts peak torque measurements, suggesting the supine position improves testing validity.
Area of Science:
- Biomechanics
- Kinesiology
- Sports Medicine
Background:
- Hip position is theorized to affect knee gravity effect torque (GET) during isokinetic testing.
- Existing research lacks data on the influence of hip position on GET and its impact on isokinetic measurements.
Purpose of the Study:
- To compare GET in seated versus supine positions.
- To evaluate the effect of seated and supine GET on isokinetic peak torque.
- To investigate the relationship between hamstring flexibility and GET.
Main Methods:
- Gravity effect torque (GET) was measured in both supine and seated hip positions.
- Isokinetic peak torque (flexion/extension) was assessed at 1.047 and 5.235 rads·s⁻¹.
- Hamstring flexibility was determined using the active knee extension test (AKET).
Main Results:
- Mean seated GET was significantly higher (5.64 Nm) than supine GET (P=0.0001).
- Significant correlations were found between hamstring flexibility and GET in both positions (P=0.0001, P=0.0058).
- Differences in GET between positions led to significant peak torque variations (P=0.0002–0.0049).
Conclusions:
- The supine position yields lower and potentially more valid GET measurements for isokinetic knee testing.
- Differences in GET due to hip position can introduce significant errors in peak torque data.
- Recommendations favor the supine position to enhance the accuracy of isokinetic assessments, particularly for injured populations.