A method for preventing muscle fatigue induced by exercise in patients with chronic obstructive pulmonary disease is described herein. The method comprises the step of providing a therapeutic laser device, wherein the therapeutic laser device generates a constant magnetic field in combination with a plurality of pulsed lights having a plurality of wavelengths. The method further comprises administering phototherapy to a muscle prior to exercising the muscle by placing the therapeutic laser device in direct contact with skin proximate to the muscle at a plurality of skin sites and pulsing the plurality of lights based on predefined parameters.
