Improvement in Knee Extension Strength through Training by Means of Combined Electrical Stimulation and Voluntary Muscle Contraction

Abstract

Weight training (WT) is the most common method of maintaining and increasing muscle strength. WT, however, is not always useful as it requires the external resistance and stabilization. We have developed a "hybrid training" (HYB) approach that avoids these problems by using electrically stimulated muscles to provide resistance to the motion of a muscle undergoing training. Here we report the efficacy of HYB compared with conventional WT for increasing the muscle strength around the knee at both slow and fast joint speeds (at 30 and 180°/sec). Two matched groups, each of 8 healthy men aged 22 years, exercised 3 times/week for six weeks. Both groups showed significantly increased strength in concentric torque at 30°/sec (HYB +28%, WT +33%) and at 180°/sec (HYB +33%, WT +38%), and also in eccentric torque at 30°/sec (HYB +25%, WT +24%) and at 180°/sec (HYB +19%, WT +30%) ( p < 0.001). HYB is comparable with WT exercising with the exception of high-speed contractions, while HYB has a clear advantage in not needing external resistance equipment or stabilization. HYB is therefore considered a useful approach for strengthening muscles when a person is restricted to bed rest or during space flight. rehabilitation; exercise; electrical stimulation; knee extension; strength © 2006 Tohoku University Medical PressExercise is essential in the maintenance of health and strength. Current approaches with weights and resistance devices are effective and are capable of increasing the strength of sedentary or de-conditioned people by 25 to 100% over a period as short as a few months (Fiatarone et al. 1994;Rall et al. 1996;Kuge et al. 2005). However, conventional weight training (WT) is not feasible and an alternative is needed when a person is restricted to bed rest or during space

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

“…Exercise which included six consecutive stimulation sessions was performed. Eccentric contractions were induced at an angular velocity of 30˚/sec as described previously [18]. In this study, we set stimulated time at 1 second.…”

“…Therefore, in the long period training trial, the current intensity was set at 50% MVC with eccentric contraction induced electrical stimulation (current intensity: 36 ± 7 mA, NRS: 5 ± 1). The subjects were trained with training system on the right limb and only ES training on the left, three times per week for 6 weeks following the previous study [18]. Pre and post training, subjects were measured thickness of VI muscle and maximum knee ex- …”

“…Therefore, the intensity of ES could not increase for strong muscle contraction and it is necessary to develop new methods for muscle strengthening without pain in the deep portion of the extremities. As a solution of problem with ES for muscle strengthening, it has reported that ES combined voluntary eccentric contraction which an agonist performs a voluntary concentric contraction against an electrically stimulated antagonist was developed [18]. However, this eccentric contraction training has some limitations [19].…”

Cycling Exercise with Electrical Stimulation of Antagonist Muscles Increases Plasma Growth Hormone and IL-6

“…1). This method is capable of increasing torque production and muscle mass in the upper and lower extremities by amounts that are comparable to that of conventional weight training (WT) (Yanagi et al 2003;Iwasaki et al 2006;Matsuse et al 2006). HTS is a beneficial technique in producing both muscle hypertrophy and strengthening in spite of using low ES intensity.…”

“…We have hypothesized that HCE significantly stimulates GH, lactate and IL-6 secretion because HTS was shown to improve muscle mass and strength (Yanagi et al 2003;Iwasaki et al 2006;Matsuse et al 2006). The purpose of this study was to show that HCE was sufficient exercise to stimulate GH, lactate and IL-6 secretion.…”