Spring washers, sometimes called disc springs, are a subtype of washers. They lend their mechanical capabilities to the unique profile of the material: when subject to a load, the irregularities of the washer compress with a proportionate resistance to return to their predeflected shape.
You should never stretch a pulled muscle to the point of pain or you risk re-injuring it. Do not overstretch the pulled muscles. Too much stretching can retear injured muscle fibers. Gently stretching a pulled muscle may relax the surrounding muscle fibers, which may be tight in response to the injury.
When stretching a pulled muscle, it should never be pushed to the point that it causes pain. Applying heat to the pulled muscle can also be beneficial. Moist heat, such as that from warm bath or shower, is better than dry heat from a heating pad. A warm bath can soothe the pulled muscle and reduce the pain.