The physiological basis for upper back pain experienced by women with large breasts is unclear but could relate to sensitivity of musculoskeletal tissues strained from the postural adaptations to large breasts. The aim of this cross-sectional study was to examine if upper back pain and breast size were associated with greater localised sensitivity of upper back musculoskeletal tissues.
119 healthy postmenopausal women (mean age 61 years) had their upper back pain (numerical rating scale), breast size (breast size score), and upper back tissue sensitivity (pressure pain thresholds (digital algometry, kPa)) assessed. The pressure pain thresholds of six skeletal sites (T2, T4, T6, T8, T10 and T12) and six muscular sites (pectoralis major, levator scapulae, sternocleidomastoid, and upper, middle, and lower trapezius muscles) were examined. Linear mixed models with random subject effects were used to evaluate differences in sensitivity at each anatomical site between participants grouped by upper back pain (nil-mild, moderate-severe) and breast size (small, large).
For most sites, the differences in sensitivity between upper back pain groups were highly significant (P < 0.002) with significantly lower pressure pain thresholds (Mean difference (MD): 74.6 to 151.1 kPa) recorded for participants with moderate-severe upper back pain. There were no differences in sensitivity between breast size groups.
Increased upper back musculoskeletal sensitivity is related to perceived upper back pain but not to breast size. It remains unclear if and how structural or mechanical factors related to breast size contribute to upper back pain in women with large breasts.

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