Background : The most important function of hip abductor muscles occurs to generate stability of the hip during walking. The superior gluteus maximus (SUP-GMAX) as well as the gluteus medius (GMED) acts as hip abductor for pelvic stability. One popular hip abductor-strengthening exercise is sidestepping. However, no study has examined the effects hip abductor muscle activation on side-stepping with reformer. Objectives : The purpose of this study was to evaluate the effects of anterior-posterior axis movement using reformer on hip abductor muscle activation during side-stepping. Methods : Fifteen healthy women were included. Surface electromyographic activity was recorded from the SUP-GMAX, GMED, and tensor fascia lata (TFL). Subjects performed three repetitions the concentric and eccentric phases of exercises lasted 2 seconds on side-stepping with thera-band and side-stepping with reformer, respectively. A paired t-test was used to compare SUP-GMAX, GMED, and TFL muscle activities between side-stepping with thera-band and side-stepping with reformer. Results : The muscle activities of SUP-GMAX and GMED were significantly increased in the stance and moving limbs during all phases of side-stepping with reformer compared to those during side-stepping with thera-band (p < 0.05). The gluteal-to-TFL muscle activation index values were ≥ 50 in the moving limb during concentric and eccentric phases, and in the stance limb while side-stepping with reformer. Conclusions : Compared to side-stepping with thera-band, side-stepping with reformer may activate the SUP-GMAX and GMED more than the TFL during anterior-posterior axis movements of the hip joint.