Abstract
This study evaluated effects of shoulder stiffness caused by a massage chair, based on the muscle stiffness of the trapezius, involving 30 limbs of 15 healthy adult females. We conducted a 15-minute massage program (the shoulder, lower back, and lower limbs) for subjects, and kept them in the same posture at rest in a sitting position for 15 minutes as a control. The trapezius muscle stiffness was measured and compared before starting the massage, after keeping a sitting position at rest, and after the massage. As a result, no significant changes in stiffness were noted after the 15-minute sitting position at rest (12.6±7.8), compared with that before starting the massage (12.8±6.2), but the muscle stiffness was significantly reduced after the 15-minute massage (8.7± 4.8). However, regarding three subjects without complaints of shoulder stiffness, the muscle stiffness increased after the massage. These findings demonstrated that mechanical stimulation by a massage chair significantly reduces muscle stiffness. However, it was not appropriate for all subjects; therefore, the necessity to establish criteria was suggested.
