Abstract
Introduction Hip muscle strength is important to assess in patients with hip and groin pain. However, hip flexion and extension strength measures are often performed near end-range positions (90° hip flexion and 0° hip extension) which causes suboptimal force production for the hip flexor and extensor musculature due to inefficient length-tension relationships. Therefore, our objective was to evaluate the test-retest reliability of testing maximal isometric strength in flexion and extension in a semi-standing position with 60° hip flexion.
Materials and Methods Thirty subjects (mean age 27 (SD 7), 43% women) were recruited. We used an anchored dynamometer to measure maximal isometric force production in hip flexion and extension in a semi-standing position with 60° hip flexion. One tester performed the tests on two separate occasions. For relative reliability, intraclass correlation (ICC 2.1) was used. For absolute reliability, standard error of measurement (SEM%), and minimal detectable change at both group (MDC%group), and individual level (MDC%ind) was used.
Results We observed no systematic bias between the tests (p≥0.193). We found good relative reliability for both extension (ICC 2.1 0.884) and flexion (ICC 0.933). SEM% ranged from 8.1% to 9.1%, MDC%group ranged from 5.2% to 5.8%, and MDC%ind ranged from 22.5% to 25.2%.
Conclusion Our study demonstrates that assessing isometric strength in hip flexion and extension in semi-standing position with the hip at 60° flexion has good relative and absolute intra-tester reliability. Therefore, this method may be useful for monitoring hip flexor and extensor strength in a position with better muscle length-tension relationships.
