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Biomedical subjects

Y Shapiro

Publications and source records attributed to Y Shapiro.

At least 109 records · Page 6Linked to original sources
PubMed1977

Prediction of heat tolerance from heart rate and rectal temperature in a temperate environment.

To determine if heat tolerance could be predicted from responses to exercise in temperature conditions, 51 young men performed 15 min of bench stepping at an average work load of 80 W at 23 degrees C. On the following day they attempted to perform 3 h of bench stepping at 40 W in heat (39.3 degrees C dry bulb, 30.3 degrees C wet bulb). Of these subjects, 4 were heat intolerant, judged by previous heat stroke episodes during field marches, 12 were heat acclimated, and 35 were unacclimated. The heat-intolerant subjects showed the highest heart rates (HR) and rectal temperatures (Tre) at 23 degrees C and in heat, and the acclimated subjects showed the lowest corresponding values. HR and Tre in each environment were combined into a single score, from 10, indicating the poorest responses, to 100, indicating the best responses. These scores at 23 degrees C when correlated with the corresponding scores in heat resulted in a linear correlation coefficient of r = 0.94 with a standard error of estimate of 8.6%. Scores of the heat-intolerant subjects were below 35, and those of the acclimated subjects were between 70 and 100. Thus heat tolerance can accurately be predicted for HR and Tre responses to exercise at room temperature.

Acclimatization↗
PubMed1977

Aerobic work capacity in sedentary men and active athletes in Israel.

Maximal oxygen uptake (Vo2max) was estimated in 1,200 sedentary men aged 18 to 50 years and in 400 active athletes aged 18 to 30 years participating in 10 different kinds of sport. The Vo2 in the 18- to 30-year-old sedentary group was 34.3 +/- 9.7 (SD) ml - kg-1 - min-1, and in the 31- to 40- and 41- to 50-year age groups a similar value of 28.1 +/- 9.9 ml - kg-1 - min-1 was recorded. The results in the sedentary group were lower than those recorded in active populations in other countries by 20 to 40%, possibly due to lack of physical activity. The mean Vo2max in 400 active athletes was 54.8 +/- 10.0 ml - kg-1 - min-1, which is very similar to Vo2max values recorded in active populations in other countries. The difference between the mean Vo2max of the 18- to 30-year-old sedentary group and that of the active one was found to be signifcant (P less than 0.005). The highest mean Vo2max values among the athletes were recorded in the group of long-distance runners (60.8 ml - kg-1 - min-1) and cyclists (61.9 ml - min-1), while unexpectedly low mean Vo2max values were recorded in the group of swimmers (50.1 +/- 8.1 ml - kg-1 - min-1) and football players (51.7 +/- 9.1 ml - kg-1 - min-1).

Adolescent↗
PubMed1977

Aerobic work capacity in high school students in Israel.

Maximal oxygen uptake (Vo2max) was predicted in 1,951 high school students aged 14 to 19 years--1,061 girls and 890 boys--from five different types of high school. The schools represented most of the ethnic groups. The mean Vo2max in the boys was 41.3 +/- 9.4 (SD), and in the girls, 34.7 +/- 10.1 ml - kg-1 - min-1; it was highest at the age of 16 in the boys, and at ages 14 and 15 in the girls. Significant ethnic differences in Vo2max were recorded; Vo2max was highest in students of Middle Eastern and North African origin [boys 42.7 +/- 9.3 (SD), girls 35.9 +/- 14.5], and lowest in the subjects of European and North American origin (boys 39.8 +/- 9.2, girls 33.2 +/- 9.3). Israel-born students showed average values (boys 40.7 +/- 9.6, girls 35.2 +/- 10.9). Significant differences in mean Vo2max values were observed in the general and agricultural high schools, and the lowest values in boys were oberved in the heshiva (parochial) high school, and in girls in the state religous high school. The differences in Vo2max in the various subpopulations in Israel can be attributed mainly to different patterns of physical activity and in part to ethnic origin.

Adolescent↗
PubMed1977

Exercise and heat orthostatism and the effect of heat acclimation and physical fitness.

Twelve trained and 16 untrained young men were administered five orthostatic tests while leaning upright against a wall, for 20 min--before exercise; after 60 min of exercise at a load of 40 W; after 15 min of exercise at a load of 80 W; after a Vo2 max test, and after 3 h of exercise at a load of 40 W in heat (39.4 degrees C DB, 30.3 degrees C WB). Eight of the untrained subjects were retested in the five orthostatic tests after 8 d of heat acclimation. The number of fainters in the orthostatic tests administered before exercise, after exercise at 40 W and 80 W, and after exercise in heat, were 3, 4, 6, and 13, respectively. There were no fainting episodes after the Vo2 max tests. Orthostatic responses in the different conditions were partially related. The trained subjects showed substantially better responses than the untrained ones (10% vs. 25% of fainting episodes), and heat acclimation resulted in marked improvement in orthostatism (decrease to 5% faintings). The results show that Vo2 max and heat tolerance account for most of the variability which determines orthostatic tolerance.

Acclimatization↗
PubMed1977

Serum glucose and lactic acid concentrations during prolonged and strenuous exercise in man.

Serum glucose and lactic acid levels were determined in 20 young volunteers prior to and following marches with increasing back pack loads (30 and 35 kg) and distances (6 and 12 km). The drop in serum glucose levels correlated well with the degree of effort. A significant mean drop in serum glucose level of 10.3 mg% was detected only in the group carrying 35 kg for a distance of 12 km. In this group, objective physiological parameters as well as subjective grading of the march's difficulty indicated the effort to be strenuous. Serum lactic acid level did not change significantly following any march. Serum glucose level may serve an indicator for determination of work's duration and intensity, determination of optimal distances for untrained hikers and of optimal loads to be carried for various distances.

Adolescent↗
PubMed1976

Effects of exposure to Finnish sauna.

Pathophysiological effects of exposure to Finnish sauna (80 to 90 C, 30 to 40% relative humidity) were investigated in 60 volunteers--33 men and 27 women aged between 18 and 63 years. The volunteers entered the sauna after a rest period of 20 min, and remained there for 20 min or until they suffered discomfort. Weight, height, rectal and skin temperatures, blood pressure, heart and respiratory rates and ECG were recorded 20 min prior to the sauna, during the sauna, and 20 min after leaving the sauna. Marked physiological changes appeared in the first few minutes in the sauna without any prodromal warning. At the 20th min the mean heart rate was 143 +/- 25 (SD) beats/min (greater than 160 beats/min in 32% of the subjects). Mean rectal temperature was 38.6 +/- 0.6 (SD) C (greater than 39 C in 22%): mean skin temperature was 40.4 +/- 1 (SD) C (greater than 40 C in 35%); mean systolic blood pressure was 130.5 +/- 26.6 (SD) mm Hg (greater than 160 mm Hg in 17%); and mean diastolic pressure was 66.6 +/- 15.9 (SD) mm Hg (greater than 50 mm Hg in 17%). The mean total sweat loss was 457 +/- 264 (SD) g. Three subjects experienced syncope, and one developed an anginal attack; ECG changes suggestive of coronary insufficiency were recorded. No decrease in blood pressure occurred in patients with preexisting high blood pressure. It is concluded that sauna bathing involves dangers to the bather's health, which may appear suddenly, without prodromal warning signs.

Adolescent↗
PubMed1976

Heat stress: comparison of short exposure to severe dry and wet heat in saunas.

Sixty subjects, 33 males and 27 females, from 18 to 63 years of age, were exposed to two kinds of saunas: the Finnish sauna (dry sauna) with an air temperature of 80 to 90 C and a relative humidity of 50%, and the wet sauna with an air temperature of 45 to 50 C and a relative humidity of 100%. There was a rest period of one week between the two experiments. For the 60 subjects the mean duration in the wet sauna was 19.6 minutes and in the dry sauna it was 17.4 minutes. After 10 and 20 minutes of exposure in the wet sauna the mean rectal temperature was 38.1 and 38.5 respectively, the mean skin temperature 40.2 and 40.4 C, the respiratory rate 21 and 22.9 breaths/min, the pulse rate 113 and 135.4 beats/min, the mean diastolic pressure 76.1 and 71.9 mm Hg, and the mean systolic pressure 115.7 and 123.5 mm Hg. Comparing the different physiological parameters in both saunas showed significant differences only during the first 10 minutes: a greater drop in diastolic blood pressure, a higher increase in systolic blood pressure, and a greater rise in pulse rate in the dry sauna. After 20 minutes there were no significant differences between any of the above parameters. It is concluded that the heat strain and hence the risk in both saunas are similar and exposure in either sauna exceeding 10 minutes may be dangerous.

Adolescent↗
PubMed1976

Sweat studies in hyperhidrosis palmaris and plantaris. A survey of 60 patients before and after cervical sympathectomy.

60 patients suffering from excessive sweating in the hands underwent cervical sympathectomy. At follow-up 1-7 years after operation the hands were dry in 55. No differences in electrolyte concentrations were found in the sweat from palms, arms, or body prior to and after the surgical intervention. Similarly no differences were found in electrolyte concentrations between healthy subjects and hyperhidrotics. Palmar sweat was hypertonic in comparison to arm or body sweat. The Na and K sweat concentrations were: palmar 50 +/- 20 and 16 +/- 7 mEq/1; arm 30 +/- 11 and 8 +/- 2 mEq/1; and body 21 +/- 20 and 4 +/- 3 mEq/1, respectively. Na/K ratio was: palmar 3.2; arms 3.6 and body 5.8. Total sweat loss prior to the operation was 5.7 +/- 4.2 g/kg BW/h; afterwards it was 5.9 +/- 4 g/kg BW/h. These equal sweat rates were associated with compensatory sweating in areas of the body not affected prior to the operation.

Adolescent↗