In addition to physiological and biochemical parameters, we study psychological indexes. Depending on the purpose of research, we use animals as well as humans.
The Effect of Exercise on Metabolism of Carbohydrates, Fats, and Proteins and its Integrated Concept
When one undergoes prolonged exercise, fatigue follows. To increase performance in competition, it is necessary to fight off such a phenomenon. How can we manage to do this? Physical adaptation through physical training is one way of achieving this. Effective use of supplements can also delay fatigue.
In our laboratory, we are studying whether taurine can inhibit the reduction in blood glucose (the energy source of the brain) during prolonged exercise. We have established an animal model which demonstrates that an attenuation of the decline in blood glucose by taurine supplementation prolongs exercise duration. We believe that glycogenolysis and gluconeogenesis in the liver are involved. Hopefully, our future research will illustrate the uptake into and the use of glucose in the skeletal muscles and brain during exercise, and will elucidate the metabolism of carbohydrates, fats, and proteins in various tissues including adipose tissues as a whole.
One of our studies in humans has suggested that ammonia produced in the skeletal muscles during vigorous, high-intensity exercise may act as a fatigue inducing factor in the brain, which was demonstrated by decreased achievement of simple addition tasks. We have also demonstrated that low- and moderate-intensity exercise is associated with an increase in blood free tryptophan (a precursor to serotonin in the brain) and we are now studying the relationship between increased free tryptophan and the performance of addition tasks. We believe that our research theme, "Exercise and Metabolism” has an extensive range of applications, not only for improving competitiveness in sports but also for preventing and treating lifestyle-related diseases.
Fatigue in the Brain and Muscles in Competitive Sports and the Effect of Supplements
We are pursuing an interesting phenomenon whereby muscle soreness induced by vigorous or prolonged exercise is alleviated by branched-chain amino acids (BCAAs, i.e. valine, leucine, and isoleucine) or taurine. Yet, there are still a number of questions to be answered, such as: When should we take BCAAs? Should it be before or after exercise? What happens if BCAAs and taurine are taken together? Is there any difference in the mechanism of inducing soreness or is it the same? There will be endless questions. If such muscle soreness can be eased, the motivation to engage in sports will be greater in those who enjoy sports for health or recreational purposes, not to mention those participating in competitive sports.
Muscle Memory - Mechanisms involved in Retention of the Effects of Exercise Training
It is widely known that muscle strength training is effective in improving athletic competitiveness, maintenance and promotion of health, and prevention and improvement of diseases. Muscle strength will be increased with strength training, which is induced by an increase in muscle mass and adaptation of the nervous system (an increase in newly used nerves).
When training is discontinued (‘detraining’), muscles will weaken. What then will happen if you start training again? Is all the previous training wasted? No, retraining will induce large and rapid recovery of strength. We have been studying this and have proved this to be the case. We are now trying to elucidate further mechanisms involved in this phenomenon.
If further studies make progress in the field of muscle memory, it will shed light on how training should be done when training is not possible due to injury or during the off-season. Considering we are living in the space age, our research will certainly provide a base upon which the training of astronauts before spaceflight can be discussed.
Training-Induced Muscle Hypertrophy and its Mechanisms
What is the significance of increasing the size of muscles? The first thing you might think of would be that it would improve competitiveness, because muscle strength increases proportionally to muscle mass. Muscle strength backed by muscle mass is essential in moving objects or moving yourself in daily life. This can be easily understood when you imagine elderly people, who have a gradual decrease in muscle mass and muscle strength. Training increases muscle mass and enhances metabolic activity, which, in turn, burns excessive fat more easily. Thus it leads to prevention and improvement of lifestyle-related disorders. In this sense, it is obviously very important to find out the mechanisms of training-induced muscle hypertrophy.
It is believed that one of the mechanisms is related to heat shock protein 72 (HSP72). Training induces muscle hypertrophy by increasing muscle protein synthesis, but at the same time it increases stresses such as heat shock, mechanical overload, and hyperoxidation. It has been reported that muscle increases HSP72 to cope with the above. Our laboratory experimentally induced muscle injury by injecting bupivacaine into the muscle of rats and studied the process, over time, of muscle regeneration. This study showed that recovery of HSP72 expression preceded the regeneration of muscle fibers, followed by changes that resemble muscle fiber regeneration.
Physical and Psychological Effect of Exercise and Environment on Development of the Body and Mind of Growing Children during their Growth Period.
In Japan, the physical fitness of children has decreased in comparison to that seen around the mid-1980s, although this decrease is showing a tendency to have stopped. This is because our life style has changed so that the amount of time and space spent on exercise and play has decreased and the number of playmates at school has also decreased. A decrease in exercise and play may have a considerably negative impact on psycho-sociological development, such as the ability to communicate.
Our laboratory has been working on the “Sanya Sasuke Physical Intellectual Moral Education Project" in cooperation with Sanya Primary School, Suginami-Ku, Tokyo since 2007. We have introduced circuit exercise using playground equipment in the school playground. We have provided exercise guidance for running, throwing and jumping. The circuit exercise also involves mutual evaluation by students with words of praise. We have been studying the effect in terms of both physical fitness and also psychological and biochemical implications. We found that the circuit exercise using playground equipment that involves positive mutual evaluation among students enhances the child’s feeling of self confidence in his or her ability to exercise and reduces salivary chromogranin A (a marker of sympathetic stress response). We are now studying how such psychological and biochemical effects influence daily amount of exercise, physical fitness, and the development of cognitive function in children. We are making progress in addressing the above questions.
We are also working in cooperation with the "Manner KidsⓇ Project". We also studied the effect of tennis schooling including teaching good manners, and found that even only one session changes their emotions for the better among children. The “Manner KidsⓇ Project" started in 2004, and more than 100,000 children have taken part in the project in various type of sports - mainly tennis but also soccer, baseball, and rugby. We are hoping that we will continue to study the results of the “Manner KidsⓇ Project" on a larger scale.