Participants

Seventeen males with mechanical LBP of nonspecific origin and known to have had the condition for more than 3 months were recruited from the local community; they comprised the LBP group. The pain had to be confined to the region between L1 and the gluteal folds without any radiation into the lower limbs. Eighteen healthy male participants (who were known to have been asymptomatic over the 12 months prior to the study) were also recruited; they comprised the AS group. The participants’ demographic data are presented in Table 1. Otherwise eligible participants were excluded if they experienced pain at the hip joint; if they had any pathology or deformity of the spine or hip joint; if they had had any surgery on the spine or hip; or if they had any orthopedic/neurological conditions or vestibular dysfunction. Ethical approval for this study was obtained from the Ethics Committee of the Hong Kong Polytechnic University. All the participants were first informed about the experimental procedures and any potential risks; their informed, written consent was then obtained before the commencement of the study.

Group demographics with mean (SD)

Abbreviations: BMI Body Mass Index, PSLR test Passive Straight Leg Raise test, SR test Sit and Reach test, VAS Visual Analogue Scale, RMDQ Roland Morris Disability Questionnaire, N/A not applicable

*p < 0.05 indicates significant difference between LBP and AS group. Data analysis with the height and body mass as the covariates revealed no significant difference