Reliability of Trapezius Muscle Hardness Measurement: A Comparison between Portable Muscle Hardness Meter and Ultrasound Strain Elastography. - Tomonori Sawada; Hiroki Okawara; Daisuke Nakashima; Shuhei Iwabuchi; Morio Matsumoto; Masaya Nakamura; Takeo Nagura (Sensors, 2020)