Neuromuscular electrostimulation in physiotherapy: A critical appraisal of controversial issues

The practice of neuromuscular electrostimulation (NMES) in physiotherapy is a controversial subject. The purpose of this paper is two-fold: (1) to provide background information of four controversial issues and (2) to critically review the clinical and experimental evidence put forward to either support or refute each of them. To fulfil this purpose, an extensive review of the English and French literature was undertaken. The present study is limited by the fact that the literature published in other languages was not reviewed. None the less, the results seem to suggest that, contrary to some personal beliefs, today's clinical neuromuscular stimulators (1) depolarise healthy muscle fibres directly through their nerve twigs and not through their membranes, (2) stimulate both slow and fast motor units, (3) evoke maximum tetanic contractions which are always weaker than maximum voluntary contractions and (4) evoke tetanic contractions which are always painful. Interestingly, there appears to be no objective and quantitative experimental evidence to support the well-reported observation that slow-rising/long-duration electrical pulses selectively depolarise denervated muscle fibres directly via their membranes.