Development of a hybrid strength training technique for paretic lower-limb muscles

A hybrid resistance exercise technique for strength training of patients with lower-limb paresis was developed. It consists of electrical stimulation-induced contractions (ESIC) superimposed on voluntary contractions to increase recruitment of motor units and the functional load capability of paretic quadriceps and hamstring muscle groups. The feasibility of this hybrid exercise technique was demonstrated in 10 able-bodied subjects during submaximal isometric contractions by eliciting greater forces than the voluntary contractions at given efforts. Mean (±SE) submaximal voluntary contraction forces (46.4% maximum voluntary contraction forces) for the quadriceps and hamstrings, respectively, were 206.0±18.0 N and 115.9±12.7 N, whereas the hybrid forces were 282.7±30.3 N and 126.1±12.9 N at ES current levels of 55.6±7.9 mA and 51.5±5.7 mA. This represented a 37.2% and an 8.8% increase over the voluntary effort for these muscle groups. Since this hybrid technique recruits additional muscle fibers for stronger contractions, the greater force overload may be more effective for the strength training of patients with lower-limb paresis