While bipedalism is a fundamental evolutionary adaptation that is essential for the development of the human brain, the erect body is always an inch or two away from falling. Although the neural substrate underlying automatic detection of one’s own body instability is an important consideration, there have thus far been few functional neuroimaging studies due to the restrictions placed on participants’ movements. Here, we used functional magnetic resonance imaging to investigate the neural substrate underlying whole body instability, based on a self-recognition paradigm that uses video stimuli consisting of one’s own and others’ whole bodies, depicted in both stable and unstable states. Analyses revealed significant activity in the brain regions that should be activated during genuine unstable body (physical) conditions: the right parieto-insular vestibular cortex, inferior frontal junction, posterior insula and parabrachial nucleus. We argue that these right-lateralized cortical and brainstem regions mediate vestibular information processing for detection of vestibular anomalies, defensive motor responding in which the necessary motor responses are automatically prepared/simulated to protect one’s body, and sympathetic activity as an alarm response during whole body instability.
The pancreas is a retroperitoneal organ critically important for intestinal digestion. Most of the pancreas consists of exocrine glands that synthesize and secrete a great majority of digestive enzymes into the pancreatic duct tributaries and on into the duodenum. It also contains important endocrine glands that produce hormones such as insulin, glucagon, and somatostatin, thus also regulating nutrition and gastrointestinal function. Since the exocrine pancreas serves a central and essential role in the digestive process, its dysfunction may result in malabsorption and malnutrition. Previous studies have shown that exocrine pancreatic dysfunction could be induced by various physical conditions such as obesity, diabetes, and aging. In addition, food consumption and dietary components have been reported to affect pancreatic enzyme synthesis and secretion. However, little is known about the effects of physical exercise on the function of the exocrine pancreas. This review focuses on the effects of physical exercise on functional and ultrastructural alterations in the exocrine pancreas. Furthermore, the importance of physical exercise on exocrine pancreas dysfunction is discussed.
Physical activity may be carried out alone or in a group. No comprehensive studies have been conducted on the associations between group exercise and health outcomes, the mechanisms underlying the associations with health outcomes, and determinants of participation in group exercise. The aim of this article is to review the associations and mechanisms between group exercise and health outcomes, and the determinants of participation in group exercise among healthy adults and the elderly without specific illnesses. Group exercise may reduce the risk of physical and mental illness by improving adherence to physical activity, psychological factors, and social relationships. While there may potentially be various determinants of group exercise, previous research has only examined specific demographic and environmental factors. Among the studies discussed in this review, few studies examined the differences between individual exercise and group exercise. Thus, the unique effects and determinants of group exercise remain unclear. Further studies examining these points are needed to develop a more complete knowledge base on group exercise.
Obesity is a major public health problem, both globally and in Japan. A nationwide approach targeting metabolic syndrome has routinely been conducted in Japan since April 2008; however, the obesity statistics have not improved. Promotion of physical activity is one anti-obesity strategy. Numerous observational studies have revealed inverse associations between obesity and physical activity; however, these results have not always been conducted as randomized controlled trials (RCTs) that can provide the highest level of evidence. Therefore, this review looks at RCTs in the field of obesity and physical activity worldwide. The Diabetes Prevention Program and the Look AHEAD study are representative RCTs in this field. A guideline for the management of overweight and obesity among U.S. adults has recently been updated using a systematic review of good- or fair-quality RCTs, but a comprehensive, systematic review of RCTs in Japan has not yet been undertaken. This review seeks to fill this gap. Overall, we only found 10 RCTs that met the three inclusion criteria ( intervention study on obesity,  overweight or obese Japanese participants, and  RCT) and did not meet the exclusion criterion (study protocol without results). Based on our review results, it is strongly suggested that more RCTs in this field be conducted in Japan.
The cold pressor test has been used to assess neural control of the cardiovascular system by observing the pressor response during the immersion of one hand in cold water. Previous studies have defined blood pressure hyperreactors to cold stress as individuals who respond with a rise of 15 mmHg or greater in their systolic and/or diastolic blood pressure and who have a higher incidence of hypertension than normal reactors. In this review, the regulatory mechanism of the cardiovascular system during the cold pressor test, and the cardiovascular responses of hyperreactors to both the cold pressor test and an isometric handgrip exercise are described. During the late phase of cold-water immersion for 2 min, the arterial baroreflex resets the heart rate to the control level, but not the peripheral resistance. Although both isometric exercise and the cold pressor test increased blood pressure by the same magnitude, baroreflex resetting of the heart rate was seen during the cold pressor test, but not during the isometric handgrip exercise. Hyperreactors showed larger cardiovascular responses to the cold pressor test than normal reactors, but not to the handgrip exercise. The pain sensation could contribute to greater increases in blood pressure in hyperreactors during cold-water immersion. The incidence of hyperreactors was higher in the middle-aged and elderly (66.7%) than in young adults (27.5%). The pulse pressure of hyperreactors during cold stress was decreased in young adults, but increased in middle-aged and elderly subjects. The onset mechanism of hypertension in hyperreactors remains to be clarified.
Thiamin (vitamin B1) has often been used as a reagent to prevent fatigue. There are two possibilities concerning the anti-fatigue effect of thiamin: 1) an ergogenic effect in a non-thiamin deficient state and 2) a supplementary effect under the condition of an increasing need for thiamin due to exercise. Thiamin is a coenzyme of pyruvate dehydrogenase (PDH), which is a mitochondrial enzyme for oxidation of carbohydrate-derived substrate to generate ATP. In a thiamin deficiency, oxidation of carbohydrate is decreased due to the reduced activity of PDH. Thus a supplement of thiamin improves carbohydrate metabolism in the thiamin-deficient state. Some reports have indicated that concentrations of thiamin in tissues are decreased by exercise, i.e. the need for thiamin intake is increased. However, direct evidence supporting the hypothesis of whether or not the thiamin requirement is increased by exercise is lacking. Although it is well documented that thiamin plays an important role in the normal function of PDH reactions, whether carbohydrate metabolism is activated by supplemental thiamin during and after exercise in a normal thiamin state is unclear. This review deals with the possibility of the administration of thiamin in preventing exercise-induced fatigue by focusing on two considerations: 1) whether the need for thiamin is increased with exercise and 2) the effect of thiamin not only on carbohydrate metabolism, but also on lipid metabolism at rest and during exercise under normal dietary conditions.
The contractile function of skeletal muscles is comprised of 3 major elements: strength (maximum muscle strength), speed (contractile velocity), and fatigue resistance (endurance). In sport science, the muscle contractile function facilitating exercise is a notable muscle function, and many studies have investigated the, training effects on skeletal muscle. In the sport science field, various training effects on skeletal muscle have been examined. For example, the level of protein forming the muscular microstructure and composition of muscle fiber type change. Recently, in skeletal muscle training experiments, correlation between changes in molecular and gene control systems in response to training have been attracting attention; however, few studies have simultaneously measured the contractile properties. In this review, the experimental significance of measuring the muscle contractile function has been outlined with reference to previous studies.