I am trying to figure out if there is a way to measure muscle strain. If I apply a force F to compress a hand grip to the maximum distance x The work done to compress the hand grip is F*x Work done = Fx Since work done = energy used, I can change the equation to: Energy used = Fx When our muscles use energy to perform work, we get muscle strain. I can change the wording to: Muscle strain = Fx If I continue to hold on to the hand grip so that it would not spring back, I need to maintain the energy used. As time passes, more energy is used (no work is done) because I can feel that the muscle strain becomes muscle pain. If I hold on to the hand grip for 10 s. Can I define the muscle strain to be: Muscle strain = Fx * 10s (and the scientific unit is Nms) I don't have to go into the cellular level to explain the various chemical reactions that take place to maintain the hand grip in compressed position. I just have to know the external force acting on my hand muscles. I can't find any literature to scientifically measure muscle strain. Can I define muscle strain as such since no one has done it?