A Novel Way of Testing Hip Extension and Flexion Strength, and Strength Ratio in the Clinical Setting: Is it Reliable?

Only 30 healthy, pain-free young adults took part, mostly university students and staff, so the results say nothing about people with hip pain, older adults, or any patient group. One physiotherapist did all the testing, so the study cannot tell you whether a second clinician would get the same numbers. There was no formal sample size calculation, and the range of plausible values around the strength ratio figure is wide enough to include both poor and good reliability. The study did not test whether the method picks up real change after rehabilitation or training, and it did not compare this position against the positions normally used, so it cannot show that this one is better. Scores were slightly higher at the second session for every measure, which may be a learning effect; a sample this size may also have missed small real differences between sessions. Strength measured while standing still may not reflect what a patient can do during dynamic, everyday activity.

The authors declare that they have no competing interests. The work was funded by two Swedish funders, Greta och Johan Kocks stiftelser and Reumatikerforbundet. The paper does not say whether the funders had any role in designing the study, analysing the data or writing it up.

Do not treat the flexion-to-extension strength ratio as a reliable clinical measure on the strength of this paper. Its agreement between sessions was only moderate, and the range of plausible values around that figure included values that would count as poor. Do not assume the method works in patients with hip pain either, since everyone tested here was a healthy young adult and the paper says so explicitly.