We have scientific laboratory evidence, not speculatory ideas, that all of these systems are responsive and active during the response of mirthful laughter. We do know that laughter is a general body exercise. We do have studies to demonstrate the involvement of the muscular system in laughter. A person can get much good physical exercise through laughter. For instance, in working with the handicapped who may be bedridden or in a wheelchair and who do not have much opportunity to get a great deal of formal exercise, laughter can be very helpful.
Laughter is an exercise like any other aerobic exercise.
Most people can laugh even if severely handicapped. The general effect of mirthful laughter is one of stimulation. For instance, in the cardiovascular system there is an increase in the heart rate. This amounts to an exercise for the heart. It not only stimulates the activity of the heart but it also stimulates the circulation.