ABSTRACT
The purpose of this study was to investigate whether a combination of electrical muscle stimulation (EMS) and cycling exercise is beneficial for improving cognitive performance. Eighteen participants (7 females and 11 males) performed a Go/No-Go task before and 2 min after i) cycling exercise (EX), ii) a combination of EMS and cycling (EMS + EX) and iii) a control (rest) intervention in a randomized controlled crossover design. In the EX intervention, the participants cycled an ergometer for 20 min with their heart rate maintained at â¼120 beats·min-1. In the EMS + EX intervention, the participants cycled an ergometer simultaneously with EMS for 20 min, with heart rate maintained at â¼120 beats·min-1. In the Control intervention, the participants remained at rest while seated on the ergometer. Cognitive performance was assessed by reaction time (RT) and accuracy. There was a significant interaction between intervention and time (p = 0.007). RT was reduced in the EX intervention (p = 0.054, matched rank biserial correlation coefficient = 0.520). In the EMS + EX intervention, RT was not altered (p = 0.243, Cohen's d = 0.285) despite no differences in heart rate between the EX and EMS + EX interventions (p = 0.551). RT was increased in the Control intervention (p = 0.038, Cohen's d = -0.529). These results indicate that combining EMS and cycling does not alter cognitive performance despite elevated heart rate, equivalent to a moderate intensity. The present findings suggest that brain activity during EMS with cycling exercise may be insufficient to improve cognitive performance when compared to exercise alone.
ABSTRACT
This study investigated the effect of an 8-week neuromuscular electrical stimulation (NMES) training programme (3 days/week) on muscle quantity and quality and single-joint performance in the knee extensors. Thirty-nine untrained young male participants were randomly assigned to NMES training (n = 21) and control (n = 18) groups. The 8-week NMES training induced significant increase in the isometric maximal voluntary contraction (MVC) torque of the knee extensors (≈9.3%), muscle volume of the individual and entire quadriceps muscles determined by magnetic resonance imaging (≈3.3%-6.4%), and a significant decrease in the ultrasound echo intensity of the vastus lateralis (≈-4.0%); however, hypertrophy of the vastus intermedius (i.e., the deep muscle) was limited (≈3.3%). In the NMES training group, the repeated measures correlations of the isometric MVC torque with the muscle volume of the entire quadriceps muscle and each quadriceps muscle were significant (rrm (20) = 0.551-0.776), whereas that of the isometric MVC torque with the ultrasound echo intensity of the vastus lateralis was not significant. These findings suggest that NMES training produces muscle strength gains, muscle hypertrophy, and partial muscle quality improvement and that the NMES training-induced muscle strength gains is caused by muscle hypertrophy in the knee extensors.
