Toshio Moritani

Effect of early implementation of electrical muscle stimulation to prevent muscle atrophy and weakness in patients after anterior cruciate ligament reconstruction

OBJECTIVE Following anterior cruciate ligament (ACL) reconstruction, restricted weight bearing and immobilization results in thigh and calf muscle atrophy and weakness. The purpose of this study was to assess the effect of electrical muscle stimulation (EMS) on prevention of muscle atrophy in patients during the early rehabilitation stage after ACL reconstruction. METHODS Twenty patients with acute ACL tears were divided into two groups randomly. The control group (CON group) participated in only the usual rehabilitation program. In addition to this protocol, the electrical muscle stimulation group (EMS group) received EMS training using the wave form of 20 Hz exponential pulse from the 2nd post-operative day to 4 weeks after the surgery. RESULTS Muscle thickness of vastus lateralis and calf increased significantly 4 weeks after surgery in the EMS group, while it decreased significantly in the CON group. The decline of knee extension strength was significantly less in the EMS group than in the CON group at 4 weeks after the surgery, and the EMS group showed greater recovery of knee extension strength at 3 months after surgery. CONCLUSIONS EMS implemented during the early rehabilitation stage is effective in maintaining and increasing muscle thickness and strength in the operated limb.

Spatial EMG potential distribution pattern of vastus lateralis muscle during isometric knee extension in young and elderly men.

The aim of the present study was to compare spatial electromyographic (EMG) potential distribution during force production between elderly and young individuals using multi-channel surface EMG (SEMG). Thirteen elderly (72-79years) and 13 young (21-27years) healthy male volunteers performed ramp submaximal contraction during isometric knee extension from 0% to 65% of maximal voluntary contraction. During contraction, multi-channel EMG was recorded from the vastus lateralis muscle. To evaluate alteration in heterogeneity and pattern in spatial EMG potential distribution, coefficient of variation (CoV), modified entropy and correlation coefficients with initial torque level were calculated from multi-channel SEMG at 5% force increment. Increase in CoV and decrease in modified entropy of RMS with increase of exerted torque were significantly smaller in elderly group (p<0.05) and correlation coefficients with initial torque level were significantly higher in elderly group than in young group at moderate torque levels (p<0.05). These data suggest that the increase of heterogeneity and the change in the activation pattern are smaller in elderly individuals than in young individuals. We speculated that multi-channel SEMG pattern in elderly individual reflects neuromuscular activation strategy regulated predominantly by clustering of similar type of muscle fibers in aged muscle.

Motor unit firing pattern of vastus lateralis muscle in type 2 diabetes mellitus patients.

Introduction: We investigated the motor unit (MU) firing pattern in type 2 diabetes mellitus (T2DM) patients by means of multichannel surface electromyography (SEMG). Methods: Eight T2DM patients and 8 age‐matched, healthy men performed a ramp‐up contraction to 20% of maximal voluntary contraction (MVC). They also performed a sustained contraction at 10% of MVC during isometric knee extension. Multichannel SEMG signals recorded from the vastus lateralis muscle were decomposed with the convolution kernel compensation technique to extract individual MU firing patterns. Results: During the ramp contraction, the extent of MU firing modulation was significantly attenuated in T2DM. Variability of MU firing rate was significantly higher in T2DM at later periods during the sustained contraction. Conclusions: Our findings suggest that T2DM patients manifest characteristic MU activity patterns due possibly to some degree of neuromuscular impairment affecting the integrity of MU firing modulation. Muscle Nerve 48:806–813, 2013

Region-specific myoelectric manifestations of fatigue in human rectus femoris muscle.

Anatomical properties between proximal and other regions within the human rectus femoris (RF) muscle are nonuniform. We aimed to clarify the possible region‐specific myoelectric manifestations of fatigue within the RF muscle by using an advanced surface electromyography (SEMG) technique.

Effect of percutaneous electrical muscle stimulation on postprandial hyperglycemia in type 2 diabetes

AIMS The aim of this study was to examine whether percutaneous electrical muscle stimulation (EMS) attenuates postprandial hyperglycemia in type 2 diabetes. METHODS Eleven patients with type 2 diabetes participated in two experimental sessions; one was a 30-min EMS 30 min after a breakfast (EMS trial) and the other was a complete rest after a breakfast (Control trial). In each trial, blood was sampled before and at 30, 60, 90, and 120 min after the meal. RESULTS Postprandial glucose level was significantly attenuated in EMS trial at 60, 90, and 120 min after a meal (p<0.05). The C-peptide concentration was also significantly lowered in EMS trial (p<0.01). On the other hand, there was no significant increase in creatine phosphokinase (CPK) concentration in each trial. CONCLUSIONS The present results provide first evidence indicating that EMS is a new exercise method for treating postprandial hyperglycemia in individuals with type 2 diabetes, especially who cannot perform adequate voluntary exercise because of excessive obesity, orthopedic diseases, or severe diabetic complications.

Subthreshold electrical stimulation reduces motor unit discharge variability and decreases the force fluctuations of plantar flexion

The purpose of this study was to examine the influence of subthreshold electrical stimulation on the force fluctuations and motor-unit discharge variability during low-level, steady contraction of the plantar flexor muscles. Seven subjects performed a force-matching task of isometric plantar flexion at 5% of maximal voluntary contraction with and without random electrical stimulation applied to the tibial nerve. During the task, the motor unit action potential was continuously recorded with fine-wire electrodes, and the inter-spike intervals of a single motor unit were calculated. The coefficient of variation (CV) of the force fluctuations and the inter-spike intervals of the motor unit discharge were significantly decreased by the intervention of subthreshold electrical stimulation, although there were no changes in the mean values. These results suggest that subthreshold stimulation reduced the motor-unit discharge variability, which in turn, increased the steadiness of the force.

The Role of Exercise and Nutrition in Lifestyle-Related Disease

Daily energy intake per person in Japan reached a peak of 2,226 Kcal in 1975 and dropped dramatically to 1,902 Kcal in 2004, nearly identical to the value during the immediate post-World War II period. However, since 1975 obesity has sharply increased despite this dramatic decline in energy intake. This may be, in part, the result of a “relative energy surplus” caused by a decline in energy expenditure due to modern industrialization that far exceeds the decreased energy intake. Bray (J Nutr 121:1146–1162, 1991) has proposed the “MONA LISA” (Most Obesities kNown Are Low In Sympathetic Activity) hypothesis, suggesting that obesity is associated with a relative or absolute reduction in the activity of the thermogenic component of the sympathetic nervous system. It is now well recognized that “middle age obesity” is strongly associated with both aging and depressed autonomic nervous system (ANS) activity, particularly the sympathetic thermogenic responses to a high-fat diet and an irregular food intake pattern. Our series of studies have suggested the decline in ANS activity that regulates fat metabolism and appetite control is potentially reversible by regular exercise training in middle-aged individuals and obese children with depressed ANS activity. In other words, habitual exercise plays a vital role in enhancing not only fat and glucose metabolism, but also in preventing obesity and enhancing appetite control. Recent studies have clearly indicated that exercising obese individuals have a much lower mortality rate and incidence of disease than lean individuals with little or no exercise. A possible explanation could be that exercise effects immune functions and myocytokines, preventing and improving lifestyle-related diseases. Finally, our recent studies on the effect of functional muscle electrical stimulation on glucose utilization during hyperinsulinemic-euglycemic clamp will be discussed together with the most recent topics on brain derived neurotrophic factors (BDNFs) that appear to influence energy metabolism, appetite, and aspects of neurocognitive function. These data strongly suggest that a lack of exercise or a sedentary lifestyle combined with an unhealthy diet may lead to accelerated ageing, diseases of the body and brain, and an overall decline in the quality of life.