Physiological effects of combined thermal and electrical muscle stimulation (cTEMS) in healthy individuals: A pilot study

Abstract

Objective. Adding superficial heat to electrical muscle stimulation may provide added effects. In this pilot study we investigated the effects on oxygen consumption of combined thermal and electrical muscle stimulation at different levels of heat and modes of electrical stimulation. Design. An observational clinical pilot study. Subjects. A total of 14 healthy persons aged 30–70 years. Methods. Subjects were randomly assigned to stimulation with different electrical pulse types in random order. At 38.2°C and 40.7°C heat intensity we measured peak oxygen uptake, capillary lactate, catecholamines, growth hormone and hemodynamics at 20% of the maximum output (194 mA) and at each individual's maximal stimulation intensity. Results. Multivariate analyses showed that electrical stimulation significantly increased peak oxygen uptake and the levels of lactate, catecholamine and growth hormone. Increasing the heat during electrical stimulation gave additional hemodynamic response and rise in growth hormone. We observed a dose-response relationship in peak oxygen uptake for increase in stimulation intensity. The highest oxygen uptake was observed with biphasic continuous stimulation at 7 Hz (p < 0.001). Conclusions. Biphasic low frequency electrical muscle stimulation elicited the highest oxygen uptake; higher stimulation intensity was not obtained by adding heat.