Fig. 3. Comparison of muscle activities of one-handed and double-handed smart phone use in stable position. %MVC: % maximum voluntary contraction, UT: upper trapezius, ECR: extensor carpi radialis, EPL: extensor pollicis longus, AP: abductor pollicis. Significant difference between One-handed and Two-handed use. *p<0.05, ***p<0.0001.