Abstract: A method and apparatus for establishing a stress index S of a subject by determining from the EKG of the subject the peak valve of the R-wave and the T-wave; determining the ratio of the R-peak to the T-peak as an initial stress value Z; determining the corresponding stress value Z after the subject experiences stress or relief of stress and establishing the stress index S as the ratio of the Z values (after/before). A stress meter is proposed to provide visual or other indications of the instantaneous stress index. Methods of exercising subjects or treating subjects in accordance with stress index values are disclosed.