Effect of Superimposed Russian Current on Quadriceps Strength and Lower-Extremity Endurance in Healthy Males and Females

Abstract

Context: More studies are needed to compare the effect of voluntary contraction, electrical stimulation, and electrical stimulation superimposed onto voluntary contraction in improving trained and untrained homolog muscle strength and lower-extremity endurance. Design: Seventy-six healthy young adults (age = 20.41 [3.07] y, 61 females and 15 males) were included in the study. Subjects were randomly divided into 3 groups as voluntary isometric contraction (IC) group, Russian current (RC) group, and superimposed Russian current (SRC) group. Methods: All training regimens were performed under physiotherapist supervision for a total of 18 sessions (3 times per week for 6 wk). In each session, 10 ICs were achieved with voluntary isometric exercise only, RC only, or RC superimposed onto ICs. Main outcome measures were trained and untrained quadriceps strength (maximal voluntary isometric contraction [MVIC]) and lower-extremity endurance (sit-to-stand test). Results: After 6 weeks of training, all outcome measures improved in all groups (P < .05), except the untrained quadriceps MVIC score of RC group (P = .562). The trained quadriceps MVIC score (P < .001, η2 = .478), untrained quadriceps MVIC score (P = .011, η2 = .115), and sit-to-stand test score (P < .001, η2 = .357) differed significantly among the 3 groups; post hoc analysis revealed that the trained quadriceps MVIC score was higher in SRC and RC groups than in the IC group, untrained quadriceps MVIC score was higher in SRC group than in the RC group, and sit-to-stand test score was higher in SRC group than in the RC group and IC group. Conclusions: RC and RC superimposed onto IC are superior to IC in improving quadriceps muscle strength, and RC superimposed onto IC is superior to RC and IC in improving lower-extremity endurance. RC superimposed onto IC and voluntary IC created cross-education effect on untrained quadriceps.

Effect of Russian current expert modes on quadriceps muscle torque in healthy adults: A single-blinded randomized controlled trial

“…In a recent study comparing voluntary isometric contraction (IC), Russian current (RC), and superimposed RC onto IC (SRC) for quadriceps strength and lower-extremity endurance found that RC and SRC outperformed voluntary IC in strength, with SRC outperforming RC in endurance [ 44 ]. These findings are consistent with previous research on neuromuscular electrical stimulation (NMES).…”