Electrical muscle stimulation and isometric exercise effects on selected quadriceps parameters*.

The purpose of the study was to compare the effects of 1) monopolar (MI) and bipolar (BI) electrical muscle stimulation (EMS) concurrent with isometric exercise, and 2) EMS (MI and BI) concurrent with isometric exercise to isometric exercise (I) alone on girth, dynamic strength, muscular power, and muscular endurance of the right quadriceps muscle. All three experimental groups completed a 6-week program of training on the right lower limb which was isometrically restrained at -30 degrees knee extension. Additionally, the MI and BI groups received low frequency (65 Hz) EMS. A control group (C) was involved in pre- and post-testing sessions only. Results indicated that 1) EMS concurrent with isometric exercise was more effective in improving quadriceps strength over a group that did no training, but was no more effective than isometric exercise alone; 2) the two EMS techniques yielded similar results for healthy innervated muscle; 3) dynamic strength was minimally increased by EMS; 4) power was positively increased more by the monopolar technique; and 5) endurance was positively increased more by the bipolar technique. It was concluded that while the two techniques of EMS concurrent with isometric exercise have the potential to positively increase selected physiological parameters in healthy innervated muscle, the greatest benefits will be noted for the weaker muscle. J Orthop Sports Phys Ther 1986;8(4):203-209.