Sex, shoulder pain, and range of motion in manual wheelchair users

Upwards of 70% of manual wheelchair users (MWUs) experience shoulder pain. Pain is more prevalent among females than males. The causes of this sex discrepancy are not understood. Decreased range of motion (ROM) has been suggested as a major contributor, but the interaction of sex, ROM, and shoulder pain has not been investigated, thus the purpose of this investigation. We divided 30 MWUs (18 males, 12 females; 21.93 +/-3.77 yr) into two groups based on self-reported shoulder pain: pain group (n = 14; 9 males, 5 females) and no pain group (n = 16; 9 males, 7 females). We used a digital goniometer to assess ROM. Participants' shoulder active and passive ROMs were tested bilaterally on the following joint motions: flexion, extension, abduction, adduction, internal rotation, and external rotation. We used a visual analog scale to assess shoulder pain. Of the participants, 47% reported shoulder pain. Overall, the no pain group had greater ROM than the pain group, with further analysis revealing this association was only significant in females during extension (p < 0.05). ROM impairments were only present in extension in females with shoulder pain. The mechanism underlying this sex difference is not clear.