Optogenetics is a relatively new and exciting field of research aimed at activating excitable cells and bypassing the need for electrical stimulation both ex-vivo and in-vivo. By utilizing Channelrhodopsin-2, researchers can simply activate these cells with blue light, something that has commonly been done in neurons, but limited work has been done with direct activation of skeletal muscle. Researchers therefore aimed to determine the feasibility of using transdermal light to directly induce isometric contractions of the triceps surae in-vivo, measured with the 1300A. The authors targeted expression of ChR2 in the skeletal muscle of mice and showed that optogenetic stimulation bypassed the nerve and resulted in similar torque production to that of electrical stimulation at a frequency of 10Hz. Higher frequencies led to a larger decay in the muscle contractions, shedding light on the significance of membrane repolarization in this process. These results showed the potential for a non-invasive alternative to electrical stimulation of muscle.