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Biomedical subjects

V Bunc

Publications and source records attributed to V Bunc.

50 records · Page 3Linked to original sources
PubMed1988

Kinetics of heart rate responses to exercise.

In order to describe the kinetics of the reaction of the heart rate (HR) to the onset of exercise of constant intensity, the half-time (t1/2) of HR can be used. First in a study of exercise of intensity corresponding to 2 W kg-1 on a cycle ergometer, the t1/2 in 15 trained male rowers and 11 untrained male students was determined. In the trained subjects t1/2 was smaller than in untrained students, mean (+/- S.D.) values being 24.10 (+/- 3.36) s and 47.12 (+/- 4.08) s respectively. In both groups t1/2 was positively correlated with resting HR, r = 0.774 and 0.846 and negatively correlated with maximal oxygen uptake (VO2max), r = -0.728 and -0.871 respectively (P less than 0.01). The regulation of HR in the transition range was concluded to be very similar to the regulation of VO2 and energy requirements. The second part of this work was concerned with responses to graded exercise. The linearity of the HR-exercise intensity relationship is maintained up to a submaximal exercise intensity beyond which the increase in exercise intensity exceeds the increase in HR. It was hypothesized that the point where HR departs from linearity in an incremental exercise test may be employed as a predictor of the ventilatory threshold (Tvent). To examine this, 28 trained male long-distance runners were tested on a treadmill and 17 untrained young male subjects were tested on a cycle ergometer using a continuous incremental protocol. The Tvent was determined from the dependence of VE on VO2 and/or VCO2. The VO2, HR and exercise intensity at Tvent were compared with the same parameters determined from the dependence of HR on exercise intensity. No significant differences were found between Tvent and HR break point levels. It was concluded from this second study that the HR break point level coincides with Tvent.

Adaptation, Physiological↗
PubMed1987

Relationships between body dimensions and resting and working oxygen consumption in boys aged 11 to 18 years.

The relationships between VO2 at rest, VO2max and VO2 during submaximal work on a treadmill with body weight, height and lean body mass assessed by densitometry were analyzed annually in 39 boys aged 11 to 18 years. Interindividual differences in VO2 at rest and VO2max during growth depended in the first place on interindividual differences in lean body mass, to a lesser extent on differences in body weight and least on differences in height. Intersubject differences in VO2 during submaximal work were primarily conditioned by differences in body weight, due to the fact that, at a given running speed, energy output depends on body weight. The differences in submaximal VO2 depended to a lesser extent on differences in lean body mass and least on differences in height. The relationships between VO2 increments and increases in body dimensions were somewhat different in 90 boys between the ages of 11 and 15 years: VO2max increments were determined primarily by changes in body weight and height, changes in lean body mass being of secondary importance. Increases in submaximal VO2 were influenced decisively by increments in body weight, followed by increments in lean body mass and least by increments in height. In the equation y = a.xb expressing the relationship of VO2max to body weight and height, the values of b at the ages of 14 and 15 years were 0.87 and 0.88 in relation to body weight, 2.63 and 2.72 in relation to height. These values are significantly higher than the theoretical values of 0.67 for body weight and 2.00 for height. Similar significant differences from these theoretical values were found for all values between the ages of 11 and 15 years.

Adipose Tissue↗
PubMed1987

Ventilatory threshold in various groups of highly trained athletes.

The ventilatory threshold (VT) was determined on a treadmill in highly trained male marathon, male and female long-distance, young male long-distance, adult male and female and young female middle-distance runners, modern pentathlonists, adult canoeists of both sexes, young male canoeists and football players, and on a bicycle ergometer in table tennis players, water slalom paddlers, young female canoeists rowers, and ice hockey players. Young female canoeists were also examined on the paddling ergometer and rowers on the rowing ergometer. VT expressed in %VO2 max was higher the longer the duration of racing performance (in marathoners 86.7%). %VO2 max at the VT level depends on the type of load and is higher the better the organism is adapted to a load. In young female canoeists and rowers examined on the bicycle ergometer, we found the VT level at 74.2% and 74.6% of %VO2 max, respectively. In the case of specific loading, we recorded 84.8% and 85.0% of %VO2 max, respectively, in the same athletes. In the case of nonspecific loading highly trained individuals may have low VT values close to the level characteristic for normal subjects. In relatively equally trained young and adult athletes we did not find significant differences in %VO2 max at the VT level (for long-distance runners, 85.2% and 85.3%, respectively, in female middle-distance runners, 82.8% and 82.7%, respectively, and in canoeists 81.3% and 78.9% of %VO2 max, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Comparison of the anaerobic threshold and mechanical efficiency of running in young and adult athletes.

We determined noninvasively in a laboratory on the treadmill the anaerobic threshold (AT) (ventilatory threshold) and mechanical efficiency (ME) of running in 7 adult male long-distance runners (mean age = 24.1 yrs) and 17 adolescents (17.0 yrs), in 8 adult female middle-distance runners (23.2 yrs), in 12 young (16.1 yrs) and in 28 adult male canoeists (22.8 yrs), and in 10 juniors (17.4 yrs). We did not find significant differences in the metabolic adaptation characterized with the help of % VO2max on the AT level between relatively equally trained juniors and adults. In long-distance runners the % of VO2max on the AT level was 85.3% for adults and 85.2% for adolescents, in female middle-distance runners 82.8% and 82.7%, respectively, in adult canoeists 78.9%, and in juniors 79.8%. In ME which characterizes the degree of adaptation to the running and depends on the years of training and thus on the differences in racing performance, the values were lower for young athletes than for adults. The ME found in long-distance runners was 25.4% for young athletes and 32.4% for adults, in middle-distance runners 28.4% and 30.3%, respectively, and in canoeists 24.5% and 26.7%, respectively. The difference was significant only in long-distance runners where the greatest difference in racing performance (about 15%) is also found. The close similarity in responses to submaximal work intensities in adults and young sportsmen or subjects of equivalent fitness suggests caution in the interpretation of agewise decrements observed in physiologic variables which may be sensitive to physical fitness status.

Adolescent↗