Methods and systems for measuring muscle sarcomere length are disclosed. In an embodiment, a method comprises illuminating a set of muscle fibers with electromagnetic radiation, measuring an intensity of the electromagnetic radiation as reflected from the muscle fibers, the measuring occurring as a function of wavelength, determining wavelengths corresponding to maximums of reflected intensity, and correlating the determined wavelengths with respective muscle sarcomere lengths. In an embodiment, a system comprises an illumination source system for illuminating the set of muscle fibers with electromagnetic radiation, and an analyzer for measuring the intensity of the electromagnetic radiation as reflected from the muscle fibers.