More research is necessary to evaluate how voluntary contraction, electrical stimulation, and combined methods affect muscle strength and endurance.
Seventy-six young adults participated in a study divided into three groups (voluntary contraction, Russian current, and combined) undergoing 18 training sessions over six weeks.
After the training, significant improvements were seen in muscle strength and endurance for all groups except one, with the superimposed group outperforming others in both measures and demonstrating cross-education effects.