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Effects of Eccentric Contractions Induced Electrical Stimulation Training System on Quadriceps Femoris Muscle

Some reports have showed that exercise involving eccentric contractions has a greater effect for muscle strengthening because the high intensity of muscle loading can be generated eccentric contraction compared to concentric or isometric contractions.

Electrical stimulation is a technique used to elicit a muscle contraction using electrical impulses. It has been reported that electrical stimulation (ES) can be effective to induce muscle strengthening. And its effectiveness is determined by the intensity of muscle loading, as well as resistance exercise. However, some studies have also indicated that ES can cause pain and discomfort.

In this study, the authors developed an eccentric contraction induced electrical stimulation (ES) training system. And the purpose of this study was to investigate whether the eccentric contraction induced ES enhance the knee extension torque compared with typical ES.

Twenty-two young untrained men (age: 23 ± 3 years old) in the acute response trial (single training) and seven untrained men in the long period training trial (for 6 weeks) were studied. The authors measured muscle thickness and knee extension torque evoked by ES with eccentric contraction training system (ES + ECC) or ES alone for the quadriceps muscle of men. The levels of pain and discomfort were evaluated using numeric rating scale (NRS) and heart rate variability. The results demonstrated that the knee extension torque of ES + ECC was higher than that of ES alone in the acute response trial. There were no significant differences in the levels of pain and discomfort between ES and ES + ECC. Additionally, ES + ECC training for 6 weeks was effective on the quadriceps muscle thickness and knee extension torque. In contrast, the ES alone training failed to increase muscle thickness and knee extension torque.

In conclusion, these results suggest that eccentric contraction induced ES would have the potential to become an effective intervention to promote muscle strengthening.


Article by Minoru Tanaka, et al, from Japan.


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