Body-sway measurements have been used as one of the methods to diagnose equilibrium disorders. A qualitative evaluation of unique body-sway characteristics of patients with specific disorders has been chiefly used. Recently, quantitatively and objectively evaluating body-sway has been advocated. This evaluation method can diagnose healthy people's body functions and has been noted as an effective body-sway method. However, methods that evaluate body-sway are not necessarily rationally united. In addition, although many evaluation parameters have been proposed, they have not been arranged objectively. It may be important to examine the following two points to rationally establish an evaluation method of the healthy people's body-sway. One is to arrange traditional evaluation methods and measurement conditions used in the past and to clarify the factors related to body-sway. Another is to carefully examine effective evaluation parameters for healthy people and set a proper evaluation criterion after inspecting their statistical validity and reliability. These general remarks clarify the above two points through a comprehensive literature review, and introduce a simple and rational evaluation methods of healthy people's health states in addition to upright standing posture control based on their body -sway.
This study aimed to examine the influence of a temporary mental stress load on center of pressure (COP) sway with time. We selected the Uchida-Kraepelin psychological (UKP) test as a mental load task (mental calculation task condition), and an easy questionnaire with little mental load as a placebo task (placebo task condition). Ten healthy young male students were measured for heart rate (HR), blood pressure (BP), subjective mental burden against the tasks, and COP sway before (Pre-test), just after (Post-test 1), 5 min (Post-test 2), 10 min (Post-test 3), and 15 min after (Post-test 4) both tasks. There was no significant change in HR and BP in the mental calculation task condition. A mental burden was significantly higher in Post-test 1 than in the Pre-test, Post-tests 3 and 4, and in the Post-test 1, it was significantly higher in the mental calculation task condition. Three COP sway parameters of mean path length, root mean square of velocity, and vector of E direction velocity showed significant differences and in Post-test 1 were higher in the mental calculation task condition, and tended to be higher in Post-test 1 than the other tests, but recovered to a baseline level at 10 min after the tasks. In healthy young adults, an excessive mental burden may temporarily affect COP sway velocity. It is suggested that considering a subject's temporal mental stress as an effect factor is important in an equilibrium test in the clinical settings.
Human's pelvis is an important structure, which links with the upper body and the two legs. The dynamics of pelvis as a key role in postural sway is determined by its' weight, the upper body and the reaction forces of the two legs. The aim of present study is to establish a dynamic pelvis model during the static upright stance, and to describe the mechanism underlying body sway in the frontal section. The dynamic pelvis model includes five joints, i.e. two ankle joints, two hip joints and one lumbosacral joint, all of which make up a multi-link system, and is driven by two pairs of muscles, the psoas major (PM) and gluteus medius (GM). Experiments on eight healthy young subjects showed that, during static upright standing, the angular sway scopes of the ankle joint on roll (medial-lateral) plane are 0.94±0.36°and 1.35±0.52°in eye-open and eye-closed conditions, respectively, while in lumbosacral joint are 0.99±0.41°and 1.27±0.72°. Ankle and lumbosacral joint rotated in almost the same degree, while, their phase difference was near 180 degrees. This means that the trunk is always kept upright during the course of body sway. Surface electromyography (sEMG) recordings from GM showed that the right GM contracted simultaneously in responding with the center of pressure (COP) excursion toward left, and vice versa. By applying body's physical parameters and assuming that the corrective torque of is regulated by PID (proportional, integral and derivative) control to the sway angle, then the body sway can be simulated. The simulation results of body sway were well consistent with experimental records, suggesting that the pelvis is an important structure in posture maintenance, and the dynamical model is useful for posture sway analyzing.
The purposes of this study were to confirm the effect of health education on the bone mass in high school boys and to investigate the proper strategy to increase the bone mass from early life.
The results were as follows.
1. The effect of the health education by pamphlet distribution was not clear but that by a lecture was obvious from the result, the rate of bone mass increase was observed in an education group.
2. The scholars whose measured values of bone mass were low at 1st grade tended to have the higher rate of bone mass increase and there are many boys who think themselves into increase the bone mass.
3. The more boys answered that they assumed the knowledge regarding healthy life in the education group, and 27.8% boys of the education group struggle to increase the bone mass.
4. The rate of bone mass increase for 2 years of the education group (7.47%) was significantly higher than that of the control group (5.28%)
From the above-mentioned results, we concluded that the health education regarding exercise and nutrition by a lecture was effective in improving the bone mass and enhancing the knowledge of better lifestyle for bone in high school boys who were at low risk of for osteoporosis. In addition, this education had a good influence on their subsequent improvement of lifestyle.