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Biomedical subjects

B Gutin

Publications and source records attributed to B Gutin.

At least 91 records · Page 5Linked to original sources
PubMed1981

Conditioning versus exercise in heat as methods for acclimatizing 8- to 10-yr-old boys to dry heat.

Two heat-acclimatization protocols were studied in 8- to 10-yr-old boys: exercise in dry heat (WH, n = 9) and exercise in neutral climate (W, n = 9). Five 90-min acclimatization sessions were conducted within a 12-day period. Base-line (BL) and criterion (CT) tests sessions were held at 43 degrees C db and 24 degrees C wb, with three 20-min exercise bouts at approximately 40 Ws. With acclimatization, the WH group showed a significant reduction in heart rate (HR) (11.4 beat x min-1), mean skin temperature (0.64 degrees C), and an increase in the population density of heat-activated sweat glands (HASG) (25.2 glands x cm-2). The W group showed a significant reduction in HR (13.4 beat x min-1) and rectal temperature (0.24 C). Total sweat rate per body surface area did not increase significantly in either group. However, the sweat rate relative to rise in core temperature increased in both groups. No significant differences were found between the two acclimatization procedures in any of the variables studies except for the HASG, which showed a greater increase in the WH group. It is suggested that in 8- to 10-yr-old boys physiological changes compatible with heat acclimatization could be achieved either by exercise in heat or by mere physical conditioning (approximately 65% of VO2max), in neutral climate. It is postulated that age-related factors associated with the thermoregulatory system prevent children from deriving full effectiveness of exercise-in-heat acclimatization protocol as used in this study.

Acclimatization↗
PubMed1980

Plasma testosterone during treadmill exercise.

Five male volunteers performed 20 min of steady-state submaximal exercise on a motor-driven treadmill at five intensities (30, 45, 60, 75, and 90% VO2 max) as well as several maximal aerobic capacity tests. Peripheral venous plasma testosterone concentrations increased above resting values in proportion to exercise intensity. However, this increase in plasma testosterone concentration was virtually equal in magnitude to the decrease in plasma volume observed consequent to the exercise bouts, resulting in no change in total testosterone contents. There was an unexpected anticipatory elevation in resting preexercise control testosterone concentration and content with increasing work intensity. The possibility that testosterone has a direct role in the organism's response to whole-body exercise is questioned.

Adult↗
PubMed1979

Physiological characteristics of elite prepubertal cross-country runners.

Eight elite cross-country runners and eight normally active boys 8--11 years of age were studied. The runners were selected on the basis of success in regional and/or national championships. Two of them had the first to third fastest mile run times for their age groups in the U.S. for three years. Tests included submaximal and maximal treadmill runs, an anaerobic capacity bicycle test, a mile run, and various anthropometric measures. A best career mile run (BCM) was used for comparisons within the running group. At submaximal work levels of 5.6 and 7 mph (124, 161, and 187 meters/min) the values for heart rate (HR) and respiratory exchange ratio (R) were significantly lower for the runners than for the non-runners. The VO2max of the runners (56.6 ml kg min) was significantly higher than that of the non-runners (46.0 ml kg min). For all subjects combined, mile run time was highly correlated with percent VO2max and percent max HR at all submaximal running speeds (r greater than 0.8). The correlation coefficient between mile run time and VO2max was -0.88. Within the running group, however, BCM was unrelated to VO2max but was closely related to percent VO2max at 8 mph (213 meters/min) with 4 = 0.86, and to anaerobic capacity (r = -0.88). There were no significant differences between the groups in age, height, weight, max HR, and percent body fat. Thus the runners had higher aerobic and anaerobic capacities, and greater utilization of fat as an enrgy sustrate during submaximal work. Within the running group, anaerobic capacity and running economy were closely related to BCM time, whereas VO2max was not.

Body Composition↗
PubMed1977

Exercise-induced changes in blood, red cell, and plasma volumes in man.

Changes in blood (BV), red cell (RCV), and plasma (PV) volumes were computed from hemoglobin and hematocrit values during submaximal treadmill exercise at 5 work intensities (30, 45, 60, 75, and 90% VO2 max) in 5 male subjects. RCV remained constant under all conditions. Changes in BV (hemoconcentration) could, therefore, be accounted for entirely by decreases in PV at all work levels. PV was a linear function of work intensity from rest through 60% VO2 max. However, a "break" occurred at that point in the data. Modeling of this break was accomplished by the use of one model (the "Fold" catastrophe) taken from the generalized catastrophe therory. However, several limitations to the acceptance of the model are presented, including the need to demonstrate a hysteresis in PV occurring at about 65% VO2 max.

Adult↗
PubMed1975

Specificity of swim training on maximum oxygen uptake.

The present study was designed to evaluate the specificity-generality of the cardiorespiratory adaptation to swim training. Fifteen male, college age, recreational swimmers utilized interval swim training procedures 1 h/day, 3 days/wk for 10 wk. Maximum physiological measures (Vo2, Ve, HR, R, and work time) were determined prior to and following swim training during treadmill running and tethered swimming Vo2max tests. Identical measures were made on 15 control subjects who did not participate in any form of training. As a result of training, the experimental subjects significantly increased (all P is less than 0.01) their swimming Vo2max (380 ml/min) max Ve (14.9 l/min,btps) and max swim time (4.0 min), and significantly decreased (P is less than 0.05) their max HR (3.5 beats/min). However, there was no significant improvement in Vo2max when the same subjects were evaluated by the treadmill running test. Differences in Vo2max and associated measures during running and swimming tests remained essentially unchanged for control subjects. The results of the present study clearly demonstrate the specificity of the cardiorespiratory adaptation to swim training in male recreational swimmers.

Adaptation, Physiological↗
PubMed1975

Physiological parameters related to running performance in college trackmen.

Submaximal and maximal oxygen consumption (VO2) and heart rate (HR) were correlated with running performance in events ranging from 100 yards to 2 miles, using as subjects 20 members of a college track team. In the first of two studies (n=11) a multi-stage walking test was used to determine VO2 and HR. Max VO2 expressed in ml/kg/min, was significantly related to 1 mile run performance but not to any of the other runs. Submaximal HR was significantly related to performance in both the 1 mile and 2 mile runs. Correlations between these physiological parameters and performance in the 220, 440, and 880 yard runs were nonsignificant. Multiple R's using max VO2 (ml/kg/min) and submaximal H were .758 and 9671, respectively, for the 1 and 2 mile runs. In study two (n=9) a running test for VO2 and HR was used, which resulted in a mean max VO2 about 7 ml higher than than elicited in the walking test, implying that for trained runners a running test was a more valid test of aerobic power. Marked relationships were found between body weight and performance, positive for the 100 yard dash and negative for the 2 mile run. Submaximal HR was again significantly related to performance in the 1 and 2 mile runs. Max VO2 was positively related to 2 mile performance and negatively related to 100 yard dash performance. Multiple R's using max VO2 and submaximal HR were .799 and .925 for the 1 and 2 mile runs, respectively. Using submaximal HR and weight the multiple R's were .777 and .945, showing that these two can account for a large amount of the variance in distance running performance. In neither study was submaximal VO2 significantly related to running performance.

Body Weight↗
PubMed1975

The prediction of maximal oxygen uptake before and after physical training in children.

Maximal oxygen consumption (V O2 max) expressed in ml/kg/min and predicted V O2 max were determined before and after 8 weeks of training in 24 boys 10-12 years. Training involved 13 of them while 11 were controls. Predicted V O2 max was based on submaximal cycling heart rate according to the Astrand-Rhyming procedure. Pre-training, V O2 max was underpredicted by 12 per cent. This resulted mainly from an apparently low cycling efficiency in these subjects compared to that implicit in the prediction equation. Although adjustments in the prediction equation could equalize the means for V O2 max and predicted V O2 max, the rather low correlation (r = .55) between these measures precluded the accurate prediction of individual scores. V O2 max remained unchanged with training while submaximal heart rate during bicycle and treadmill exercise showed a significant decrease, resulting in predicted increases in V O2 max in children. Since V O2 max was actually unchanged, the prediction falsely indicated an improvement. Furthermore, despite a significantly lower heart rate in the trained group, there was no difference in predicted V O2 max between the groups post-training. These findings indicate that if V O2 max is the parameter of interest, it would seem to be more satisfactory to measure it directly until more reliable methods of prediction are developed.

Analysis of Variance↗