Repeated intense skeletal muscle contraction leads to a progressive loss of force-generating capacity. This decline in function is generally referred to as muscular fatigue. Since the work of Fletcher and Hopkins (1907), it has been known that fatigued muscles accumulate lactic acid. Intracellular acidosis due to lactic acid accumulation has been regarded as the most important cause of fatigue during intense exercise. Recent challenges to the traditional view, however, have suggested that lactic acid plays a role in muscle contraction distinct from that implied by earlier studies. This brief review presents (1) a short history of our understanding about lactic acid that explains the early acceptance of a causal relationship between lactic acid and fatigue, (2) evidence to show the temperature dependence of acidosis-induced changes and the beneficial effect of acidosis, and (3) a proposal that lactate production retards, not causes, acidosis. These findings require us to reevaluate our notions of lactic acid, acidosis and muscular fatigue.
The present paper provides a broad overview of the three main dynamic models-the rigid body model, the deformation (deformable body) model, and the fluid structure model-that are used when investigating physical exercise and sports techniques from a biomechanical or ergonomic standpoint. The benefits of such models and the precautions that should be taken in their use and interpretation are investigated, as are some potential future models. Rigid body system models, among which the mass-spring model and rink-segment model are the most common, have conventionally been the core models in the fields of physical education and sport. This type of model will likely continue to evolve and be applied to various problems. At the same time, it is true that rigid body models are ill-suited to the study of certain techniques. For this reason, deformation and fluid structure models have been developed for use in such research and for problem solving. Analyses using conventional physical education and sport models usually describe sporting techniques in detail by calculating joint torque based on kinematic data from actual movement coordinates in an inverse dynamic manner (inputting displacement and outputting force). This has, to date, produced outstanding results, providing a “description” of the action taking place. In future, analyses that incorporate direct dynamics (inputting force and outputting displacement) based on elicited force will also be required in conjunction with this descriptive approach. A combination of these two approaches will enable simple “predictions” to be carried out on an appropriate level. The ultimate goal of such predictions will be to optimize the performance of the technique. In future, therefore, it will be important to perform modeling that incorporates description and prediction, yielding a model for optimization of the action.
The study of human growth and development is a basic science, and such studies focus on age-related changes in morphology and physiology mainly during the first 20 years of life. During this period, rapid changes occur in size, physique and body composition and in various body systems. Already, many issues related to such changes have been suggested by the Subcommittee on Growth and Development of the Japanese Society of Physical Education. The study of growth and development as a rule does not deal with urgent problems; rather, issues related to age- and sex-associated variation and to the timing and tempo of the growth spurt and sexual maturation tend to dominate research in this area. This paper reviews several issues related to these broad topical areas: longitudinal studies, secular trends, the human growth curve, physiological age, and physical performance and activity. (1) Longitudinal studies are essential for understanding the processes of growth and development, especially for investigating individual differences among individuals. There are, however, difficulties associated with longitudinal designs so that there have been relatively few complete longitudinal studies. (2) Secular trends in body size and the timing of maturation were general phenomena in Japan, Europe and the United States, although the trends have slowed and/or stopped in some countries. It is, however, still important to understand factors that underlie secular trends. (3) Translating data for individuals into growth curves is a common method for analyzing human growth. To this end, mathematical fitting of curves to data for individual children is an important method that permits identification of important markers, especially peak height velocity and age at peak height velocity, among others. There are several protocols for curve fitting. (4) Physiological age is a concept that relates to the biological maturity status of individuals. Bone (skeletal) age and dental age are common indicators, but there have been only a few applications in clinical areas and in biological anthropology/human biology. (5) Interest in growth- and maturity-related changes in physical performance and activity is rapidly increasing, especially in the context of the current epidemic of childhood obesity and the apparent decline in physical fitness and activity. Physical activity is often considered important to support normal growth and maturation, but its specific effects require systematic evaluation.
The present study was carried out in order to examine critically, from a feminist perspective, the identity politics of female physical education (PE) teachers and its limitations. The points discussed include how female PE teachers have acquired their own territory in the cultural field of PE, the basis of the identity politics they face, and why the Japan Association of Physical Education for Women (JAPEW) has placed such high emphasis on dance-education. The present study was based on articles written by PE teachers in some PE journals. As pointed out by a number of researchers, there has been widespread and strong gender bias in the field of sport and PE in Japan. In this situation, female PE teachers have had to be politically active in establishing their own value and territory in the field of PE. Members of the JAPEW have considered dance-education to be an affirmative aspect of the organization, and have used it as a strategy to avoid being buried in the male-oriented field of PE. An important facet of this political view has been the concept of “the special character of the female”. However, the gender politics of female PE teachers have created a number of problems: First, female PE teachers have been placed in a very narrow category, dance-education. Second, this has led to the exclusion of female PE teachers who are not proficient in dance-teaching. Thus, a “center/periphery” hierarchy of female PE teachers has been created, and this has limited the identity politics of female teachers in the field of PE.
The purpose of this study was to investigate the characteristics of hazard and risk perception for outdoor activities by primary school pupils and their related factors. The subjects were 87 fourth-grade pupils and 90 sixth-grade pupils. Illustrations depicting two typical outdoor activities—canteen cooking and hiking—were prepared. The subjects were instructed to (1) find hazardous objects or point out any dangerous behavior in the illustrations (hazard perception), and (2) estimate how dangerous certain items were on a 10-cm scale (risk perception). A questionnaire to evaluate camp and play experience and self-evaluation of behavioral characteristics was conducted, and records of the pupils' visits to the nursing room because of injuries (most of them minor) were also collected. The characteristics of hazard and risk perception were also compared with those of outdoor activity instructors. The results were as follows: (1) Hazard perception did not differ much in quantity—but did differ in content—among the groups, and criteria of risk evaluation also differed between instructors and pupils. The pupils tended to underestimate potential risk to the body, but overestimated the risk of spreading fire even when the potential for injury were low and risk of indirect danger. (2) Experience showed a significant positive relationship to some of the perception indices among fourth-grade boys, but not among sixth-grade pupils and fourth-grade girls. (3) Hazard perception showed a significant positive relationship to the number of injuries recorded by the nursing room only among fourth-grade boys. These results suggest that it is important to educate pupils to give them a realistic concept of dangerous situations and to evaluate their potential risks.
The People's Republic of China, which is a multiethnic country, considers policies focusing on ethnic minorities to be an imprtant national issue. The present study was designed to examine the identity of ethnic minorities by focusing on national meets involving traditional athletic sports among such ethnic minorities as one aspect of national policy. The 1st and 7th National Meets of Athletic Sports for Ethnic Minorities were held respectively in 1953 and in 2003, during which a change from modern sports to ethnic sports was recognized with respect to the sporting events emphasized. Subsequently, a change from those ethnic sports to post-ethnic sports was recognized. The participation of members of minority groups in these National Meets appeals to their ethnic identity, leading to the creation of a pan-ethnic minority identity. Since in addition to ethnic minorities, the Han race also participates in the National Meets, the Meets function as a cultural mechanism by which the Pan-ethnic minority identity is replaced by the Chinese ethnic identity, thus equating the Chinese ethnic identity with the official national identity. The representation of culture at the National Meets has been changing from a state in which “ethnic minorities represent different cultures” to one in which “ethnic minorities represent their own cultures.” These facts suggest that ethnic sports in China contribute to political and ethnic integration, whereby ethnic sports are useful for affirming ethnic identities that are manifested at various intensity levels, and that ethnic sports serve as a medium whereby changes in identity can take place.
This study was designed to clarify how a “comprehensive community sports club” (referred to as sports club hereafter) was established by explanation and persuasion through conversations during the fostering phases. Fieldwork and the collection of conversation data was performed at 14 meetings held during the period from April 9, 2003 to November 6, 2003, in “A” district of Kiryu city in Gunma prefecture. The fieldnotes used can be described as sketches with simultaneous notes inserted. The conversation data collected were transformed into open coding and focused coding, and then analytic categories were selected. As a result, a core category, “justification for the sports club”, and five constituent categories, “preferential use of a public institution”, “superiority over existing sport club”, “making full use of community centers”, “application of members' social positions”, and “conventions of the local inhabitants” were formed. The members who participated in the meetings attempted to justify the establishment of the sports club in this district by discussing and utilizing the above categories.
This paper examines (1) the profile of Dr. Kenzo Futaki, (2) why he advocated the abdominal breathing method, and the purpose and effects of the method, (3) how the Futaki breathing method is performed, and (4) how it compares with the Okada method. The Futaki breathing method involves abdominal breathing, and was originally advocated because anyone could use it. Futaki clearly indicated that his method was not original, but was inspired by, and borrowed from, Atsutane Hirata's method. Hirata's method is a return to an Eastern style of breathing technique, as compared to the practices of the time, which were largely Western-inspired training methods, i.e. with little emphasis on breathing at all. Futaki was a boy of frail constitution until he tried Hirata's method when he was 16-17 years old. He attributed his newfound health to this method. Later he became a doctor, and researched the method further. He found medical/scientific support for the Hirata method. The Futaki method, abdominal breathing, differs significantly from the Okada method, known as reverse breathing or chest-type breathing.
Kentaro Sasaki (1923-1994) was a teacher who established a new method of physical education using essay writing in the postwar period when new methods of physical education had been sought for. He is also known as a teacher who advocated “physical education for defending our lives”. The purpose of this research is to clarify the meaning of his slogan “defend our lives” and the process and his intention in advocating this approach. Sasaki began to advocate his ideas in the autumn of 1953. Based on materials written by him and the members of his kinan sakubun kyoiku kenkyukai (“Kinan Essay Writing Workshop”), I analyzed the following points: (1) the trend of study of the kinan sakubun kyoiku kenkyukai, (2) Sasaki's writing concerning “life”, and (3) his “physical education theory”. It was apparent that he used the term “defend our lives” in two ways: (1) in the sense of “building up our health”, and (2) in the sense of “making students more aware of factors that hinder health-building”. Moreover, I prove that his advocacy of “physical education for defending our lives” came not only from the fact that he was against “education for giving up our lives” (which had always been pointed out by many people), but also from his critisism of the fact that physical education and its teachers at that time did not defend the lives of children, in other words, from his criticism of the teaching method that he had been adopting.
This study was conducted to examine the influence of a university physical education program on the volume of physical activity in male university students with disabilities. Three university freshmen who attended a health-related physical activity program (adapted course) participated in the study. Student A had diseases of the internal organs and a disabled right leg, student B had chronic nephritis, and student C had a chronic herniated intervertebral disc. As well as guidance or lectures, each class involved recording of attendance and measurement of body weight and fat (10 minutes), an assignment based on behavioral sciences and reflecting on a one-week self-monitored physical activity record (20 minutes), sports activities (45 minutes; e.g., boccia), and documenting the sports activities peformed (5 minutes). Students attending a class were challenged with two types of assignment. One was a class-practice assignment that included a component on behavioral sciences. The other assignment involved self-monitoring of a physical activity record for one week. In general, a tendency for an increase in the number of steps counted by a pedometer was observed throughout the 13 classes. Furthermore, self-efficacy and decisional balance for exercise also improved between pre- and post-attendance. Based on these results, it was concluded that the physical education program had a positive influence on the volume of physical activity of university students with disabilities.
In order to investigate muscle activity during overhand baseball pitching, surface EMG analysis of muscles in the shoulder girdle and upper limb was performed. The subjects were two college baseball players. Surface EMG was recorded from 25 portions of 16 muscles: the long and short head of the biceps brachii, the coracobrachialis, the brachialis, the lateral, medial and long head of the triceps brachii, the anterior, middle and posterior deltoid, the sternocostalis of the pectoralis major, the latissimus dorsi, the upper, middle and lower trapezius, three portions of the serratus anterior, the pronator teres, the flexor carpi radialis, the flexor carpi ulnalis, the extensor carpi radialis, the extensor digitorum, the extensor carpi ulnalis, and the brachioradialis. After rectifying the surface EMGs, their linear envelopes were extracted with a digital low-pass filter. The duration, timing and similarity of these muscle activities before and after ball-release were analyzed quantitatively through auto-correlation and cross-correlation analysis of the envelopes. The biceps and the brachialis were activated in the cocking phase and follow-through phase, and played a role in preparing for acceleration and deceleration in each phase. The triceps was activated in the acceleration phase and elbow joint extension, and contributed to the increase of ball speed by minimizing the moment of inertia about the longitudinal axis of the upper limb. The coracobrachialis was activated from the cocking phase until ball-release, and contributed to the horizontal extension of the shoulder joint. The latissimus dorsi and the pectoralis major were activated in the acceleration phase, and the duration of their activity was shorter than that of the other muscles. The activities of the trapezius and the serratus anterior differed between the two subjects. These activities in one subject were simultaneous in the acceleration phase, and those in the other were separate in the cocking phase. These activities probably represent differences in the control of scapula motion during pitching. The peak activities of the forearm muscles were concentrated in the ball-release phase, and the duration of activity was longer in the extensor muscles than in the flexor muscles. This type of correlation analysis is useful for extracting information about muscle activity during baseball pitching.
A study was conducted to examine the nature and extent of the syllabus of elementary schools in Japan between 1891 and 1912. The syllabuses were obtained from the NationalDiet Library, public libraries and university libraries throughout Japan. One hundred and eighty-eight syllabuses, including 101 physical training syllabuses, were obtained. The details involved in creating the syllabuses were classified according to year, prefecture, author, and subject. The results of the investigation were compared among three periods, I: 1891—1899, II: 1900—1906, III: 1907—1912. It was found that the total and average of thephysical training syllabus were almost the same during periods I and II. Physical training was an elective subject during the first period. However, because of the results during thefirst period, the findings indicated the importance of physical training for this period. The number of syllabuses during period III was lower than for periods I and II. Most of the syllabuses were devised in the Chubu area including Shizuoka Prefecture during period I, and in the Kanto, Chubu and Kinki areas during period II. Most of the authors of the syllabuses during period I were teachers at maintained schools, whereas during period II most were teachers at elementary schools attached to normal schools. Physical training was an elective subject during period I, whereas it was compulsory during period II. Compared with the other subjects, there was an apparent trend for physical training syllabuses to be sufficiently implemented in both periods.