Measurement method for erector spinae muscle activity during patient handling using inertial sensor and shoe-type force sensor by Kitagawa, Kodai, Matsumoto, Koji, Iwanaga, Kensuke, Ahmad, Siti Anom, Nagasaki, Takayuki, Nakano, Sota, Hida, Mitsumasa, Okamatsu, Shogo, Wada, Chikamune