Toshiaki Miyamoto

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

Type 2 diabetes mellitus patients manifest characteristic spatial EMG potential distribution pattern during sustained isometric contraction.

AIM The purpose of the present study is to investigate spatial surface electromyography (SEMG) potential distribution pattern in type 2 diabetes mellitus (T2DM) patients. METHODS Nine T2DM patients and nine age-matched healthy men (CON) performed a sustained isometric knee extension at 10% of maximal voluntary contraction for 120s. Multi-channel SEMG was recorded from the vastus lateralis muscle by means of 64 electrodes. To characterize spatial SEMG potential distribution pattern, modified entropy and correlation coefficients between same electrode locations were calculated at 15, 60 and 120s for the root mean square values. RESULTS At 60 and 120s, modified entropy in T2DM was significantly lower than those in CON (p<0.05). Correlation coefficients for T2DM were significantly higher than those for CON at 60 and 120s (p<0.05). CONCLUSION From these results, we suggested that T2DM patients continue to recruit limited and same motor units during the sustained contraction at low force level.

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.

Low-intensity electrical muscle stimulation induces significant increases in muscle strength and cardiorespiratory fitness

Abstract The aim of this study was to investigate the effect of low-intensity exercise training using belt electrode skeletal muscle electrical stimulation on muscle strength and cardiorespiratory fitness in healthy subjects. Nineteen healthy subjects were allocated into control or intervention groups; in both groups the participants kept regular physical activity while the intervention group underwent 30 min B-SES training at 3–4 METs for four weeks. Knee extensor muscle strength and cardiorespiratory endurance during incremental exercise test were measured at baseline and after four weeks for all participants. The relative change of knee extensor muscle strength in the intervention group was significantly higher than control group (p < .05). Also, oxygen uptake at ventilator threshold and peak oxygen uptake during incremental exercise test significantly increased in the intervention group when compared with control group (p < .05). This study showed that prolonged low-intensity B-SES training resulted in significant increases in muscle strength and cardiorespiratory fitness in healthy subjects. Our present work suggested that B-SES training could assist patients who might have difficulty performing adequate voluntary exercise because of excessive obesity, orthopaedic problems and chronic diseases such as cardiovascular disease and type 2 diabetes. An intervention study conducted for such patients is strongly recommended.

Gender difference in metabolic responses to surface electrical muscle stimulation in type 2 diabetes

OBJECTIVE The aim of this study was to examine whether or not there is a gender difference in metabolic responses to surface electrical muscle stimulation (sEMS) in type 2 diabetes (T2DM). METHODS Ten men and eight women with T2DM participated in two sessions; in both sessions the subjects were investigated after a breakfast and that in one occasion they underwent 30-min sEMS while in the other they were followed while resting. Blood and gas exchange data were compared between genders as to the extent of blood glucose and non-esterified fatty acids responses to sEMS. RESULTS The time course change of blood glucose concentration after sEMS did not statistically differ between genders while sEMS could attenuate postprandial blood glucose level regardless of gender (p<0.05). Women had a lower respiratory quotient and lactate concentration during sEMS when compared with men (p<0.05). CONCLUSIONS This study indicated that sEMS might have resulted in lower anaerobic glycolysis in women as compared to men with T2DM. sEMS is expected to be a new exercise method in T2DM. Determining the possible gender differences and precise mechanisms might further shed some light for the efficacy of sEMS use for clinical practice.

Effect of Neuromuscular Electrical Stimulation on Brain-derived Neurotrophic Factor

Brain-derived neurotrophic factor (BDNF) has been considered an essential mediator responsible for the beneficial effects of physical activity in preventing cognitive impairment. This study aimed at examining the effects of a single bout of neuromuscular electrical stimulation (NMES) on levels of BDNF in the plasma and on cognitive performance in healthy adult men. Thirteen healthy adult men participated in three experimental sessions. The first session was 30 min of NMES to both legs, the second was 30 min of cycling exercise at the intensity of 60% peak oxygen uptake, and the third was 30 min of complete rest. Blood was examined for plasma BDNF levels and glucose concentrations, and cognitive performance tests were performed before and after each session. A single bout of NMES significantly increased plasma BDNF levels (p<0.05), which were equivalent to the amount of plasma BDNF released during the exercise session (p>0.05). However, there were no significant changes in cognitive performance between the sessions (p>0.05). The present study found that a single bout of NMES significantly increased plasma BDNF to levels normally present during moderate voluntary exercise. Therefore, NMES could serve as an alternative method of exercise, and might shed light on individuals for whom voluntary physical exercise is contraindicated.

Acute cardiovascular responses to multiple sets of high-velocity resistance exercise in healthy adults

ABSTRACT The aim of this study is examining the effects of multiple sets of high-velocity resistance exercise (HVRE) on cardiovascular responses. Fifteen healthy adult men participated in two experimental sessions: one comprised three sets of resistance exercise performed against high-intensity resistance exercise (HIRE) at low velocity and the other three sets of HVRE performed against reduced load at high velocity. Blood pressure (BP), heart rate (HR), stroke volume (SV) and cardiac output (CO) during both sessions were evaluated using impedance electrocardiography. The increases in BP, HR and CO were significantly lowered during HVRE compared with HIRE (p < 0.05). In contrast, there was no significant difference in SV between sessions (p > 0.05). This study suggested that the increases in BP and CO during HVRE were lower than those during HIRE although HVRE required performing fast movement. HVRE might be applied to patients for whom HIRE is contraindicated because of cardiovascular diseases.

Near falls predict substantial falls in older adults: a prospective cohort study

Little is known about the relationship between near falls and substantial falls in older adults. Clarifying this relationship would be helpful to assess fall risk in greater detail. The purpose of the present study was to clarify whether near falls predict future falls.

Effects of increased physical activity on body composition, physical functions, vascular functions, HR-QOL, and self-efficacy in community-dwelling elderly people

[Purpose] The objective of this study was to clarify the effects of increased number of steps on body composition, physical functions, vascular functions, health-related quality of life (HR-QOL) and self-efficacy in elderly people. [Subjects and Methods] The subjects were 47 elderly persons who resided in Port Island in the Chuo Ward of Kobe City in Hyogo Prefecture, Japan. After the calculation of the mean preintervention physical activity (PA), the subjects were instructed to increase their PA to a target baseline + 1,300 steps/day. Body composition, physical functions, vascular functions, HR-QOL, and self-efficacy were measured at baseline, after 3 and 6 months. These items were compared between a group that increased their PA and a group that did not. [Results] After 6 months, 26.1% of the subjects achieved the PA target. No significant improvements were observed in body composition, physical functions, vascular functions, or self-efficacy for either group after 3 and 6 months. However, the HR-QOL improved significantly after 6 months in the achievement group. [Conclusion] Although the intervention to increase PA did not produce significant improvements after 6 months in body composition, physical functions, vascular functions, or self-efficacy, the HR-QOL improved significantly during this relatively short period.

Response of brain-derived neurotrophic factor to combining cognitive and physical exercise

Abstract Purpose: Brain-derived neurotrophic factor (BDNF) is well known for its potential to promote brain plasticity. It has been proposed that combining cognitive and physical exercise (CCPE) may have the potential to generate more synergistic benefits in cognitive function than either cognitive exercise (CE) or physical exercise (PE) alone. The purpose of this study was to examine acute responses of peripheral BDNF levels and cognitive performance to CE, PE, and CCPE. Methods: Thirteen healthy adult men participated in four experimental sessions; a 30-min CE, a 30-min cycling PE at an intensity of 60% peak oxygen uptake, a 30-min CCPE at the same intensity as PE, and a 30-min session of complete rest. Plasma BDNF levels and cognitive performance were measured before and after each session. Results: Both PE and CCPE significantly increased plasma BDNF levels (p < .05). CE led to no significant increase (p ≥ .05), and there was no significant difference in peripheral BDNF levels between PE and CCPE (p ≥ .05). No session induced a significant change in cognitive performance (p ≥ .05). Conclusions: Our study suggests that CE and PE have different responses of peripheral BDNF levels and that CCPE had no additional or synergistic effect on peripheral BDNF levels compared with PE alone. This study offers further insights into the potential mechanisms underlying the respective roles of CE, PE, and CCPE for peripheral BDNF levels and cognitive performance.