Four male and five female elderly subjects (ages 62 to 82 years) participated in this study to determine the effect of cutaneous neuromuscular electrical stimulation (NMES) on quadriceps and hamstring peak isometric and isokinetic torque production. Following habituation, subjects performed voluntary isometric and isokinetic (1.05, 1.57, and 2.09 rad•s-1) quadriceps and hamstring contractions with and without NMES on a Kin-Corn dynamometer. Tests were performed on 4 separate days and randomized for muscle group, contraction velocity, and NMES application. The maximal tolerable level of NMES (symmetrical biphasic waveform, 0.250 msec duration, 50 pps) was applied via two pairs of surface electrodes each placed over motor points of the quadriceps and hamstring muscles. Peak torque produced with NMES alone ranged from only 1 to 20% maximum voluntary isometric contraction. For both muscle groups, there were no significant differences (p >0.05) in either peak isometric or isokinetic torque between voluntary effort with and without NMES. Reasons for the lack of benefit of voluntary plus NMES effort on peak quadriceps and hamstring isometric and isokinetic torque may include: (1) a poor tolerance of the elderly subjects to NMES, or (2) an adequate ability of the elderly subjects to recruit motor units during voluntary effort alone. Regardless, these data imply that voluntary isometric and isokinetic quadriceps and hamstring contractions supplemented with NMES did not result in the additional recruitment of motor units in these nonimpaired elderly subjects.
- electrical stimulation
- lower extremity
- muscle performance
ASJC Scopus subject areas
- Public Health, Environmental and Occupational Health