A method for increasing muscular volume of a muscle in a human is provided. The method comprises injecting a composition comprising hyaluronic acid (HA) into one or more than one location of a muscle, thereby increasing the muscular volume as compared to before the injection. The muscle may be an arm, leg, chest, back or buttock muscle, or any other desired muscle. A method for altering a contour of a muscle in a human is also provided, which comprises obtaining an image of the contour of the muscle, determining a new contour, injecting an HA composition into one or more than one location of the muscle to obtain the new contour, thereby altering the contour as compared to before the injection. A use of a composition comprising HA for increasing muscular volume of a muscle in a human is also provided, where the composition is for injection into muscle.