[Purpose] To evaluate differences in pectoral muscle tightness according to arm abduction
angle and to determine the best arm abduction angle for stretching of pectoral muscle
tightness in breast cancer patients. [Subjects and Methods] Horizontal abduction
differences of shoulders were measured bilaterally by arm abduction to 45°, 90°, and 135°
to determine the best arm abduction angle for measuring pectoral muscle tightness.
Thirty-two patients were divided into three pectoral muscle stretching groups (A: 45°, B:
90°, and C: 135°). We measured the shoulder range of motion, scores of the Disabilities of
the Arm, Shoulder, and Hand, European Organization for Research and Treatment of Cancer
Quality of Life Questionnaire and the Breast Module, and pain levels (using a visual
analog scale) before and after therapy. [Results] The differences in degree of horizontal
abduction between shoulders were significantly larger for arm abduction to 90° and 135°
than that to 45°. Groups B and C showed greater improvements in horizontal abduction
limitations than group A. [Conclusion] Horizontal abduction differences between shoulders
are prominent when arms are abducted to 90° and 135°. The appropriate arm abduction angle
for measuring horizontal abduction and effective stretching of pectoral muscle tightness
may be >90°.