Recent research has shown that the human motor cortex can be modulated by the application of static magnetic fields through the scalp. Transcranial static magnetic field stimulation (tSMS) has since received significant attention as a new non-invasive brain stimulation (NIBS) technique alongside conventional methods, such as repetitive transcranial magnetic stimulation and transcranial direct current stimulation. The advantages of the strong neodymium, iron and boron (NdFeB) magnet used in tSMS over other NIBS methods include the ease of use, absence of uncomfortable sensations for subjects, a lack of necessity for high operational skills and expensive devices, and conclusive sham stimulation allowing for controlled experiments and randomized controlled clinical trials. Hence, tSMS may be a new potential NIBS tool to modulate cerebral excitability.
Several G protein-coupled receptors that transmit signals in response to dietary free fatty acids (FFAs) as well as endogenous metabolites, such as lactate and 3-hydroxybutyrate, have been discovered. These receptors are shown to sense levels of energy substrates or metabolic states of the body, and regulate metabolism and endocrine functions of various organs to maintain energy homeostasis. The receptors for FFAs and hydroxy carboxylic acids (HCAs) appear to be involved in several metabolic disorders including obesity, diabetes and atherosclerosis. In this review, we summarize the functions of FFA and HCA receptors in physiology and pathophysiology, and discuss their implications for the treatment of metabolic diseases.
The epidemic of obesity has become a serious health challenge in both developed and developing countries. Since the identification of leptin, a secretory protein from the white adipose tissue, secretory proteins have become recognized as important regulators of energy metabolism. We previously identified neudesin as a novel secretory protein. We also showed that neudesin was strongly expressed in central the nervous system of embryonic and adult mice, and was expressed in various peripheral tissues of adult mice. Thus, in this review, we discuss the physiological roles of neudesin and focus on its involvement in energy metabolism. We generated neudesin knock-out (KO) mice, and showed that they were resistant to high-fat diet (HFD)-induced obesity. Neudesin KO mice were protected from HFD-induced insulin resistance and hepatic steatosis. Furthermore, neudesin KO mice showed increased energy expenditure due to enhanced sympathetic nervous activity (SNA). Thus, resistance to HFD-induced obesity in neudesin KO mice was the result of increased energy expenditure. Neudesin KO mice also showed increased heat production and fatty acid oxidation in the adipose tissue. These results suggest that neudesin might act on neurons and adipocytes to suppress SNA. In conclusion, we establish the role of neudesin as a supressor of energy expenditure via regulating SNA. Neudesin is a novel regulator of energy metabolism and might be a target for the treatment of obesity and obesity-related metabolic syndrome.
Passive walking-like leg movement in the standing posture (PWM) has been used to activate neural mechanisms responsible for generating gait movement and to prevent disuse syndrome including muscle atrophy, bone mass loss and joint contracture as a rehabilitation tool for individuals with gait disturbance. However, circulatory responses to PWM have not been fully determined, despite the potential risk of orthostatic intolerance from standing posture. Quiet standing (QS) causes a decrease in blood volume in the ventricles due to the pooling of blood in the lower extremities and subsequent decrease in stroke volume. On the other hand, cardiac contractility and heart rate increase to maintain cardiac output due to enhancement of sympathetic nerve activity. The enhancement of cardiac activity is linked to vasovagal responses characterized by bradycardia and the drop in arterial blood pressure and symptoms such as pallor, lightheadedness, hyperventilation and blurred vision, especially in young individuals. In addition, QS can cause orthostatic hypotension due to loss of sympathetic control of the heart and vasculature in individuals with cervical spinal cord injury. Vasovagal response and orthostatic hypotension may lead to syncope. However, PWM has been shown to induce a decrease in cardiac activity compared to that during QS in young individuals and a large increase in arterial blood pressure in individuals with cervical spinal cord injury, suggesting that PWM reduces the risks of vasovagal responses and orthostatic hypotension and, consequently, syncope. The efficacy and safety of PWM suggests that PWM is a useful tool for rehabilitation in individuals with gait disturbance.
Kendo is a high load-type sport, especially for the lower leg muscles. The purpose of this study was to evaluate changes in the hardness of the gastrocnemius medialis (GM) using real-time tissue elastography (RTE) during training at a Kendo training camp. Eleven college male Kendo athletes participated in a 5-day Kendo training camp, and the hardness of the GM, the circumference of the lower legs, and the ankle range of motion (ROM) were examined during the course of training. The strain ratio of the GM to a reference material was used to estimate changes in muscle hardness during the training period. The results showed that the strain ratio of the GM significantly increased at days 3, 4, and 5, in comparison to the baseline values obtained prior to training (p < 0.05), indicating that the hardness of the GM increased after high-intensity exercise. Meanwhile, the circumference of the lower leg did not change over the course of training; while the ROM values significantly decreased at days 4 and 5 relative to the baseline, suggesting the increased muscle hardness resulted from increased muscle stiffness. These results suggest the muscle hardness of athletes who engage in repetitious high load-type sports are tense on the next day of hard training, and the hardness continues, as in this case, until the last day of camp. In addition, RTE measurements of muscle hardness may allow a more sensitive detection of changes in muscle properties than what is possible with ROM measurements.
The aims of this study were to describe longitudinal changes in objectively measured physical activity (PA) in Chinese children and to investigate the associations of such changes with weight status, gender, and day of the week. This study was conducted on 50 boys and 43 girls. Children underwent measurements in 2011 (age 7-8 years, 2nd grade) and in 2014 (age 10-11 years, 5th grade). The children were divided into: normal weight (NW) or overweight/obese (OW/OB) groups based on weight status recorded in 2014. PA was quantified by steps measured using a uniaxial accelerometer, then total PA time and time spent performing moderate to vigorous PA (≥ 3 METs) were analyzed separately for weekdays and weekends. The daily PA outcomes and normalized PA outcomes per hour (steps, total PA time, and moderate to vigorous PA) declined with age in the OW/OB group on weekends for boys and on both weekdays and weekends for girls (p < 0.05). But no change was observed in the NW group of boys and girls. The percentages of achieving the global recommendations by WHO also declined with age in the OW/OB group for boys on weekdays (p < 0.05). Moreover, they had significantly less percentages of achieving the WHO recommendations than that of the NW group for boys on both weekdays and weekends in 2014 (p < 0.05). Our findings suggest that longitudinal changes in PA, predominantly in the quantity and intensity of activity, are related to weight status in children. Prevention of this decline in PA among children in OW/OB children, particularly on weekends for boys and on both weekdays and weekends for girls may be a suitable health promotion target.
Ground reaction force (GRF) in sit-to-stand (STS) movement is used mainly for evaluating lower extremity muscle strength. We attempted to evaluate not only lower extremity muscle strength, but also balance ability from GRF in STS movement. This study aimed to investigate the relationship between GRF variables, including composite variables, which are the combination of parameters representing lower extremity muscle strength and balance ability, and mobility limitation and falls. This study included 381 community-dwelling older adults (73.8 ± 5.3 years; 45.9% men). We measured the maximal rate of force development over 87.5 ms/body weight (RFD8.75/w) and peak reaction force/body weight (F/w) to evaluate lower extremity muscle strength. We also measured lateral load sway divided by the change in vertical load/second (vx/vw) to evaluate balance ability. We then created composite variables of these variables. To perform logistic regression analysis separated by gender, three groups based on the tertile of each variable were used. Composite variables that comprised the Rv score, which was the combination of RFD8.75/w and vx/vw, and Fv scores, which combined F/w and vx/vw, were especially effective for evaluating the risk of mobility limitation in both genders. In evaluating the fall risk, the Rv and Fv scores of the poor group in women only showed significantly higher odds ratios of 2.74 (95% CI: 1.21 - 6.20) and 3.02 (95% CI: 1.31 - 6.96), respectively. These results suggest that the composite variables, Rv and Fv scores, are superior for evaluating risks of mobility limitation and falls, rather than each single variable.