Relationship between helmet temperature and tympanic temperature during american football practice / 体力科学

Purpose: The purpose of this study was to examine the relationship among helmet surface temperature (Thl), head top temperature (Thd) and tympanic temperature (Tty) during American football practice in summer. Methods : The subjects were collegiate American football players. Temperatures were measured in August in 1993 and 1994. Thl, Thd and Tty were measured by infrared tympanic thermometers. Environmental temperatures that were measured were dry-bulb temperature (Td), wet-bulb temperature (Tw), globe temperature (GT) and wet-bulb globe temperature (WBGT) . Results: Significant correlations were observed among all measured temperatures (P<0.0001) . High coefficients of correlation were observed among Thl, Thd and GT. The highest relationships were observed between Thl and Thd (r=.727), and between Tty and Td (r=.766) . The coefficient of correlation between Tty and Thl was higher than that between Tty and Thd. Heat stress of the whole body (F1; heat stress factor: Tty, Td, Tw and WBGT, proportion=71.4%) and head environment factor (F2 ; helmet factor : Thl, Thd and GT, proportion=14.3%) were chosen in factor analysis. A close relationship was observed between both factors (r=.773) . Both GT and Thl showed a high correlation with Thd, which suggests the influence of radiant heat through a helmet on the whole body. Conclusion : The temperature in a helmet is a micro environment temperature surrounding the head. Accordingly, the heat load is reduced by taking the helmet off frequently during football practice.

Effect of a moderate work for 7 successive days on concentrations of serum erythropoietin and hemoglobin of female university students / 体力科学

In an attempt to study the effect of a moderate work load on the concentration of serum erythropoietin and hemoglobin in young women, 8 female university students with a high hemoglobin content (group H), 7 female university students with a low hemoglobin content (group L) and 7 female university students with a tendency to be anemic (group A) were subjected to moderate work for 7 successive days in summer.<BR>Each subject pedalled at a constant work load of 1.25kp at a cycling rate of 50rpm for 60min every day. Blood samples were drawn from the cubital vein under basal conditions on the day before training, the fourth day of training and the day after the training period. The results obtained were as follows; Group H showed a significantly higher erythropoietin concentration before training than groups L and A. The concentration of erythropoietin in group H decreased slightly during the training period, whereas those in groups L and A increased, although the differences were not statistically significant.<BR>The concentration of serum iron in group H was significantly higher than that in group L before training. The former decreased significantly during the training period, whereas the latter was maintained at a lower level. The differences in blood constituents found among the three groups before training lessened after one week's moderate exercise.<BR>The increase in Hb concentration in the subjects in groups L and A after training might have been induced by the augmented secretion of erythropoietin due to training for 7 successive days.

Vascular hunting reaction of volleyball players to cold air exposure with special reference to finger shape / 体力科学

Observations on the digital vascular hunting reaction to cold air exposure and measurements of physical characteristics were made among male university students: 88 non-athletic; 18 tall, lean non-athletic; 26 volleyball players. Experiments were carried out at about 3 p, m. in winter. The subjects sat at rest on a chair for 30 min in a room at 22°C and inserted their left hands up to the wrist with the palm downwards into a chamber at -10°C for 30 min. The skin temperature on the center of the dorsal surface of the distal phalanx of the left middle finger was recorded continuously starting at 5 min before the cold exposure. The physical status of volleyball players was characterized by large stature, a low body fat and long fingers, while that of tall and lean non-athletic subjects was characterized by light body weight, a low body fat, and long and slender fingers. In each group, the higher the temperature before cold exposure, the higher were the skin temperature at the first temperature rise during cold exposure and the mean skin temperature during cold exposure. The mean value of the finger skin temperature during cold exposure for volleyball players at a given value of skin temperature before cold exposure tended to be lower than those for non-athletes. The mean value of the finger skin temperature during cold exposure for volleyball players was lower than that for non-athletes. Among the non-athletes, tall and lean subjects showed a lower mean skin temperature during cold exposure. The skin temperature during cold exposure tended to be lower when the length of the finger was longer and the ratio of finger girth to length was smaller. The lower mean skin temperature during cold exposure for volleyball players might result from injuries and shocks to the finger received during volleyball training.

STUDIES ON PHYSIQUE OF MALE ATHLETIC UNIVERSITY STUDENTS IN COMPARISON WITH NONATHLETIC UNIVERSITY STUDENTS AND METHODS FOR ASSESSMENT OF PHYSIQUE / 体力科学

Anthropometric measurements were obtained on 126 male nonathletic first year university students (N-1), 178 male nonathletic third year university students (N-3) and 114 male athletic third year university students (A) . The mean values of height and body weight for group A were significantly larger than those for groups N-1 and N-3. Group A showed significant larger mean values of girth of chest, abdomen, thigh and upper arm than groups N-1 and N-3. Physical status of group N-1 was a little shorter and slender than that of group N-3. Group A showed significantly greater mean values of Rohrer's index and Brugsch's index than groups N-1 and N-3. The mean values of skinfold thickness and body fat (%) caluculated by using prediction formula from mean skinfold thickness for group A were significantly smaller than those for group N-3 and were essentially the same as those for group N-1. Bigger physique and smaller body fat content of athletes could be explained as due to a result of physical training and might be considered as the cause of superior physical fitness of athletes.<BR>The following prediction equations for standard body weight (W) from height (H) using mean values of body weight and height (W and H) and their standard deviations (cW and aH) are proposed for the evaluation of overweight and underweight.<BR>W=3W/HH-2W<BR>and W=σW/σHH-σW/σHH+W<BR>Plotting of body weight and body fat content in standard measure against height in standard measure was used to compare physical characteristics of athletes with those of nonathletes.

EFFECT OF PHYSICAL TRAINING IN A HOT ENVIRONMENT ON HEAT TOLERANCE OF MEN / 体力科学

In an attempt to study the effect of physical training in a hot environment on physiological responses to heat and heat tolerance of men, six male university students were exposed to a combination of muscular exercise and environmental heat for 20 successive days in summer. Muscular exercise was performed on a bicycle ergometer at constant work of about 8 R.M.R.t at the cycling rate of 50 r.p.m. for 2 hrs in the room with a temperature of 30°C and 70%, R.H. Sweat test was performed on the day before the beginning of physical training, on 7th, 14th and 211th days of physical training. Sweating was produced by immersing both legs to just below the knees into stirring water of 42°C for 90 min after staying for 30 min in a climatic chamber of 30CC with 70%, R.H. Sweat volume observed in sweat test increased progressively throughout the period of physical training. Na concentration in sweat at a given sweat rate continued to decrease during the period of physical training and heterogeneity of the local sweat rate and Na concentration in local sweat was reduced by physical training in a hot environment. Rise in rectal temperature induced by a given heat stress decreased significantly during the first week, thereafter showed a trend bo be smaller. The mean value of heat tolerance index I, the magnitude of disturbance induced in the body concerning thermal regulation and water-electrolyte metabolism, decreased considerably during the first week of physical training, thereafter decreased slightly. Thus it might be said that improvement of heat tolerance was induced mostly during the early period (about 1 week) of successive exposure to a combination hard work and environmental heat. This improvement of heat tolerance accompanied by marked reduction of physical strain in terms of temperature regulation might be induced at the cost of increase in disturbance of water-electrolyte metabolism.

COMPARISON OF THE HEAT TOLERANCE BETWEEN ATHLETES AND NONATHLETES / 体力科学

Physiological responses to heat and heat tolerance were examined in summer and winter on 13 male athletic university students and male nonathletec university students. After staying for 30 min. in a climatic chamber maintained at 30°C with 70% relative humidity, sweating reaction was examined far 90 min, by immersing both legs up to the knees in a stirring water bath of 42°C.<BR>Both groups showed significantly greater sweat volume, significantly lower Na concentration in sweat and considerably lower rise in rectal temperature and less increase in heart rate in summer than in winter. In both seasons, athletes showed smaller volume of sweat, lower Na concentration in sweat, lower rise in rectal temperature and less increase in heart rate than nonathletes.<BR>It is concluded that heat tolerance of athletes was superior to that of nonathletes when assessed by our heat tolerance indices and this superior heat tolerance of athletes could be explained due to a result of physical training. Heat tolerance index, representing the magnitude of physiological strain in the body induced by heat load, was modified by using relative increase in heart rate in place of salt loss. It can be said that the modified heat tolerance index is useful as a substitute of the original heat tolerance index in field studies.

STUDIES ON PHYSIQUE AND BODY SHAPE OF ATHLETES WITH SPECIAL REFERENCE TO DIFFERENCES IN PHYSIQUE AMONG ATHLETES OF VARIOUS KINDS OF SPORTS / 体力科学

Anthropometrical measurement were obtained on 178 male nonathletic university students and 168 male athletic university students (Swimming, Handball, Soccer, Rugby, Running, Thrower, Judo and Gymnastics) aged 18-22 years.<BR>The results obtained were as follows<BR>The mean values of height and body weight for nonathletes were 170.2cm and 59.7kg respectively. The mean values of height and body weight for athletes except gymnastics and long distance runner were larger than those for nonathletes. Athletes showed larger mean values of girth of chest than nonathletes (86.1cm) . The mean values of girth of upper arm and girth of thigh for nonathletes were 26.9cm and 50.6cm respectively. The mean values of girth of upper arm for athletes except basketball, long distance runner and jumper were considerably larger than that for nonathletes. Athletes except long distance runner, jumper and gymnastics showed larger mean values of thigh than nonathletes. The mean values of skinfold thickness for athletes except heavy weight class of judo were thinner than that for nonathletes and the percentage of body fat calculated by using the prediction formura from mean skinfold thickness, body surface area and body weight for athletes was smaller than that for nonathletes<BR>Plotting of body weight and body fat content in standard measure against height in standard measure with family of iso-deviation line was used to compare the body composition and body shape of athletes with those of nonathletes. In this plotting, physical characteristics could be expressed as the difference (R) between the points representing the mean value of athletes on the origin, (the mean values of nonathletes) and ratio of deviation (r) from standard line representing correlation of body weight or body fat content to height for nonathletes. Plotting R against r with family of lines of the same height was proposed to differentiate physical characteristics of athletes participating in different kinds of sports and to evaluate the effect of training on physical characteristics. Plotting of girth of upper arm and girth of thigh in standard measure against girth of chest was used for the evaluation of difference in body shape of athletes.