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Biomedical subjects

V Bunc

Publications and source records attributed to V Bunc.

At least 37 records · Page 2Linked to original sources
PubMed1991

[Conversion of the intensity of loading from the bicycle ergometer to a treadmill and to field training in women].

When evaluating the standard of functional fitness, state of training or work capacity of subjects, when diagnosing loads, when assessing training of healthy subjects and sportsmen and locomotor rehabilitation of patients usually two types of ergometers are used--a pedalling ergometer and a treadmill. Each of these ergometers has its specific properties, advantages and shortcomings. For the practical use of results of functional examination in the laboratory, where the majority of our diagnostic departments possesses only a pedalling ergometer it is necessary to convert the load intensity from the bicycle to a treadmill and to the field where physical training is usually implemented. Based on our measurements in groups women with different grades of training, differing as to age, it is possible to elaborate a general equation which relates the load intensity on the pedalling ergometer P/W.kg-1 and the speed of running on the treadmill with a zero gradient v/km.h-1 in the form v = 3,695.P-1,419. This relationship can be used with an error of cca 12% in the zone of submaximal load intensities (up to 90% of the maximal load intensity). For P lower than 3.9 W.kg-1 this equation can be used for direct conversion to flat ground. For higher load intensities there is the relationship v = 3,156.P + 0.446 which has the same error of 12% as for even ground.

Adolescent↗
PubMed1991

[Energy requirements in women during pedalling on a bicycle ergometer].

The bicycle ergometer is the most frequently used equipment for loading tests for the purpose of functional diagnosis and for the purpose of locomotor rehabilitation. The energy required to meet this locomotor activity is within a wide range of load intensities which depends linearily on the intensity of pedalling. The steepness of this linear relationship which characterizes the degree of adaptation of the organism to this type of locomotor activity is the smaller the more the investigated subjects are adapted to the load. In general it depends on the degree of training, age, sex, strength, pedalling frequency, on the load protocol and on the biomechanical conditions during pedalling (e.g. the height of the saddle). Based on our measurements in a group of untrained women of different age and in trained women of different age it can be demonstrated that all individual relations between energy characterized by means of VO2 and the intensity of the load - P is within the zone where the upper borderline is formed by the equation VO2(ml) = 11.00.P (W) + 403 and the lower borderline by VO2(ml) = 9.90.P (W) + 252. The basic relationship, independent on the degree of training, age and strength, valid in the zone of pedalling frequencies of 60-80 rot. min-1 and in the zone of load intensities of 75-325 W has the shape of VO2(ml) = 10.60.P(W) + 269. The maximum error of assessment of VO2 by means of the load intensity is 9% or less.

Adolescent↗
PubMed1991

[Anaerobic "all-out" stress tests: selection of the type and duration of stress].

In the diagnosis of prerequisite conditions for short-term highly intensive activity, performed under conditions of oxygen deficit anaerobic loading tests are used. Contrary to tests of constant performance, "all-out" tests follow up changes of performance in the course of time, i. e. they record the maximal anaerobic performance as well as the decline of performance in the course of the test. In a group of 17 subjects three types of loads were compared (bicycle ergometry, a test repeated jumps and running) and two periods of anaerobic tests--45 s and 120 s. The results achieved in different tests--total work, maximum performance, decline of performance, post-load lactate concentration in blood--differed depending on the type of load and duration of the test. Correlation analysis did not reveal a close relationship between the results of different anaerobic tests, there was however a relationship between the maximum performance and the total work at the level of general physical fitness. The longer variant of the test--120 s--did not prove more suitable, neither from the aspect of the assumed markedly higher lactate cumulation in blood nor from the aspect of maximum performance, as compared with the 45 s test. A close relationship was revealed between the results of the 45 s and 120 s jumping and running test but not between the results of bicycle ergometry. The post-load lactate concentration cannot be considered a highly reliable indicator of the level of the anaerobic energy metabolism in the working muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Ventilatory threshold and work efficiency on a bicycle and paddling ergometer in top canoeists.

The purpose of this investigation was to determine the effect of increasing specific (paddling ergometer) and non-specific (bicycle ergometer) work load on the parameters at the ventilatory threshold (VT) and on work efficiency (WE) during increasing exercise ergometry. When highly trained male canoeists were given an unspecific exercise load, the values of %VO2max at VT were close to the values characteristic for an untrained population (72.3 +/- 5.3% VO2max). When the same subjects were given a specific work load, they produced values typical for highly trained athletes (83.4 +/- 2.5% VO2max). Non-specific exercise produced WE values close to those of untrained subjects on the bicycle ergometer (23.3 +/- 2.1%), and when loading is specific, the groups of working muscles are smaller, producing lower WE values (14.7 +/- 3.5%). It was concluded that the responses to submaximal exercise intensities in the case of nonspecific loading suggests caution in the interpretation of physiological variables which may be sensitive to training status. The assessment of VT and WE as supplementary characteristics during laboratory measurements, enables us, along with other parameters, to ascertain not only the effectiveness of the training process used, but also the specificity of a loading apparatus.

Adaptation, Physiological↗
PubMed1991

Exercise intensity conversion from a bicycle ergometer to a treadmill.

In the evaluation of the general functional fitness and/or work capacity of subjects for the purpose of exercise diagnostics, physical fitness enhancement in untrained healthy subjects or sportsmen and exercise rehabilitation of patients, two types of ergometers are generally used: a bicycle ergometer and a treadmill. To facilitate the conversion of results of functional examinations made in the laboratory to field conditions, where, as a rule, physical activity is performed, the intensity of exercise assessed on the bicycle ergometer must be converted to that on a treadmill and vice versa. Measurements on a bicycle ergometer and treadmill in differently trained groups of men can be supplemented with data from the literature to develop a general equation which relates exercise intensity on the bicycle ergometer P (W.kg-1) and running speed on the treadmill v (km.h-1) as v = 3.544.P +/- 0.625. In the submaximal range of exercise intensities (20-80% of maximal aerobic power) this relationship is independent on the training status, age, body weight, strength and speed capacity of the subjects examined. The above equation may be used in the submaximal exercise intensity range with a maximum error of about 12% or less.

Adaptation, Physiological↗
PubMed1990

[A simple method for estimating the level of physical fitness].

Physical activity is becoming an integral part of everyday life. In order to modify and control this activity we need simple and readily available criteria for the control of physical fitness. One of the possible approaches how to resolve this problem is to use motor tests. The most frequently used method for evaluation of physical fitness proposed by Cooper, based on measurement in the American population may involve, when used under our conditions, inaccuracy of estimates of physical fitness and be associated with some difficulties regarding the 12-minute period of the test. The author submits therefore tables for the estimation of physical fitness elaborated with regard to our population standards and general relations between the velocity of movement and energy required for this activity expressed indirectly by oxygen consumption. The basic element of evaluation is the velocity of movement of a 2000 to 3000 m track. The tables were prepared for men and women aged 14-65 years and make it possible to estimate below-average, average and above-average levels of physical fitness. The error of assessment of VO2 max and thus also of the estimate of physical fitness level varies round 15%.

Adolescent↗
PubMed1990

[A simple method of determining the intensity and duration of physical exertion].

Determination of the intensity and duration of physical activity with respect to the individual condition of the organism is essential for the effective control of physical training. One of the possible methods of establishing those quantities is making use of the dependence of intensity on the duration of physical exercise. Using semi-logarithmic coordinates (the intensity of exercise is given in the decomal system, the period of time in logarithms) this dependence is of the linear type. The straight line constructed from the limit (highest) intensities of exertion and the relevant times of exercise in any given individual, which must take into account that individual's state of health and fitness, cuts the plane of all conceivable combination of intensity-duration, into two semi-planes. All the actual combinations of those variables exploitable for training purposes are found in the semi-plane situated to the left of this line. With regard to the purpose of physical training it is then possible simply to choose the required intensity of exercise and to find the respective zone of the duration of this exercise, or it is possible to choose the duration of physical exercise and to read from the graph the respective zone of intensity. This intensity can be put either in terms of the speed of movement or, indirectly, in terms of the heart rate. This method of determining the intensity and duration of physical exercise can be used for all activities of the cyclic type, e.g. running, cycling, swimming and so on.

Humans↗
PubMed1990

[Energy requirements in women during running on a treadmill and running over terrain].

Running is the most frequently used training method of promoting aerobic efficiency, functional capacity and fitness as well as weight reduction. The energy demand on running expressed indirectly in terms of oxygen consumption correlated with 1 kg body weight (VO2.kg-1) can be established on the basis of the running speed (v) using different nomograms and graphs. These relations are linear within the range of submaximum exertion of training intensity, approximately within the range of 20-90% of maximum oxygen consumption. The relationship between VO2.kg-1 and the running speed generally depends on the sex, age, amount of training practice and on the inherent speed capabilities. Based on the measurements of women of different training practice and age, supplemented with data drawn from literature, the authors established an "average" relationship, independent of age, record of training practice and the speed norm valid for the running carpet in the form of VO2.kg-1 = 2.804. v (km.h-1) + 8.922. The error in determining VO2.kg-1 within the range of the speed of 8-18 km.h-1 is approximately 8% or less. Similarly, using nomograms which facilitate the transfer of the running speed on the running carpet to the outdoor speed, the authors found a general equation for a flat terrain in the form of VO2.kg-1 = 3.359. v + 3.308 which can be used for the speed range of 8-16 km.h-1 with the same error as the one obtained indoors. The above relations can be used for estimating the reactions of the organism to indoor or outdoor exertion with the aim of establishing suitable training exertion intensity.

Adolescent↗
PubMed1990

[The effect of body constitution on work capacity evaluated by means of mechanical efficiency].

The utilizable sources of energy of the human organism are relatively restricted where by interindividual differences are not substantial, while differences in physical performance are extreme. The capacity to transform chemical energy into mechanical work, sometimes described also as the work capacity of the organism is evaluated by means of mechanical efficiency--ME. In men with varying amounts of training (incl. untrained ones), differing significantly as to the percentage of body fat (3.8-17.2%), assessed by measurement of ten skinfolds, the authors assessed ME on a treadmill. The highest ME values were recorded in trained sportsmen (endurance runners--32.4%), lowest in untrained middle-aged men (16.9%). The authors found a close negative correlation of ME and maximal oxygen consumption per kg body weight and values of body fat percentage. With the increasing percentage of body fat the values of ME decline, the prerequisites for effective transformation of chemical energy of the organism into mechanical work are reduced and the work capacity of the organism declines.

Adult↗
PubMed1989

[Evaluation of energy requirements in basic physical activity].

When evaluating the influence of physical activity on the organism it is important to know its energy requirement. A positive influence is exerted only by those physical activities, when during their application a certain minimal threshold level is exceeded. The level depends on the purpose for which these activities are performed. When evaluating the energy requirement of different physical activities, it is important to respect body weights of the investigated subjects. The coefficient of energy requirement is expressed in kJ.min-1.kg-1. The author presents values of basic physical activities which may be used by the public. Based on a cross-sectional survey of the Czechoslovak population the authors recommend for stabilization of the attained level of physical fitness and performance a minimal extra physical activity expressed as the energy output per week and amounting to 6000-8000 kJ per week. To achieve an increasing effect, this level must amount to at least 13,000 kJ per week.

Energy Metabolism↗
PubMed1989

[Noninvasive determination of the anaerobic threshold in middle-age men].

The "anaerobic threshold" was estimated non-invasively in two groups of untrained middle-aged men (Mean age 31.4 +/- 4.8 and 51.8 +/- 5.4 years) simultaneously from minute volume dependence on oxygen consumption or CO2 output, and by means of pulse rate kinetics estimation, both at a growing intensity of exertion. The values of selected function variables (VO2, pulse rate and performance in pedalling) at "threshold" level showed no significant difference in either estimation in both absolute and relative quantities (expressed in per cent of maximum values). Very close relationships were found between the values of selected function parameters at "anaerobic threshold" level estimated with the above two methods (p less than 0.005 in all cases). The two methods of "anaerobic threshold" estimation are interchangeable under the following conditions: the initial intensity of exercise at about 50% VO2 max level, the duration of each degree of exertion ranges between 30 and 150 seconds, the differences in the intensity of exercise between different degrees are roughly 4 to 6 pulses/min, and the total number of the degrees of exercise is 5 to 8. Estimations of pulse rate kinetics with the intensity of exercise rising can be utilized for the determination of the "anaerobic threshold" even in persons of advanced age both under laboratory and under field conditions.

Adult↗
PubMed1989

[Non-invasive determination of the "anaerobic threshold" using heart rate kinetics].

The functional parameters at the level of the "anaerobic threshold" (ANT) are used very frequently to characterize aerobic functions of the organism. For estimation of the ANT most frequently changes of the LA blood concentration in relation to an increasing load are used. The LA concentration depends to a considerable extent on the state of glycogen reserves in muscles which may change as a result of physical loads and as a result of dietary intervention. Ventilation parameters and values of the GR are practically independent on glycogen reserves. For the evaluation of mutual relationships between parameters at the level of the ventilation ANT and the level of ANT assessed by means of changes of the HR, both ANT values were assessed in a group of trained endurance runners on a treadmill and in a group of untrained young men on a bicycle ergometer. For practical use both ANT estimations can be considered identical, assuming that when using the HR for assessment of ANT we implement the following conditions: 1. The initial intensity of the load is at the level of 50 VO2max. or lower. 2. The duration of different grades of the load is 30-150 s. 3. Differences in the intensity of the load between different grades are 4-6 strokes. 4. The total number of loads varies between 7 and 12.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Ventilatory threshold and mechanical efficiency in endurance runners.

In order to evaluate changes in parameters at the ventilatory threshold (VT) and in mechanical efficiency (ME) during training in the years 1982 and 1983 we tested seven top-class endurance runners on a treadmill. The VT and ME were assessed during their training period (January 1982 and 1983) and during their competitive period (March and July 1982). The maximal functional variables were almost constant during the training year, the maximal change in VO2max being about 5%. Similarly, VO2 at the VT was almost constant; the maximal change in VO2 at VT was also about 5%. Substantially greater changes, about 10%, were recorded in the velocity of running at the VT, at which the maximum was attained in July (18.9 +/- 0.8 km.h-1 or 5.25 +/- 0.22 m.s-1); this value was significantly higher than values assessed during the remaining tests. The greatest change, about 23%, during the training year was found in ME, for which the maximum was attained in July (35.7% +/- 2.1%). This was not significantly different from the value recorded in March (34.5% +/- 3.3%), but both values were significantly higher than those recorded during the training period. We can therefore conclude that in highly trained endurance runners the times needed to attain the optimal conditions for sports performance differ from the point of view of special speed training and from the point of view of mechanical-metabolic readiness.

Adult↗
PubMed1989

Energy cost of running in similarly trained men and women.

The energy demand of running on a treadmill was studied in different groups of trained athletes of both sexes. We have not found any significant differences in the net energy cost (C) during running (expressed in J.kg-1.m-1) between similarly trained groups of men and women. For men and women respectively in adult middle distance runners C = 3.57 +/- 0.15 and 3.65 +/- 0.20, in adult long-distance runners C = 3.63 +/- 0.18 and 3.70 +/- 0.21, in adult canoeists C = 3.82 +/- 0.34 and 3.80 +/- 0.24, in young middle-distance runners C = 3.84 +/- 0.18 and 3.78 +/- 0.26 and in young long-distance runners C = 3.85 +/- 0.12 and 3.80 +/- 0.24. This similarity may be explained by the similar training states of both sexes, resulting from the intense training which did not differ in its relative intensity and frequency between the groups of men and women. A negative relationship was found between the energy cost of running and maximal oxygen uptake (VO2max) expressed relative to body weight (for men r = -0.471, p less than 0.001; for women r = -0.589, p less than 0.001). In contrast, no significant relationship was found in either sex between the energy cost of running and VO2max. We conclude therefore that differences in sports performance between similarly trained men and women are related to differences in VO2max.kg-1. The evaluation of C as an additional characteristic during laboratory tests may help us to ascertain, along with other parameters, not only the effectiveness of the training procedure, but also to evaluate the technique performed.

Adolescent↗
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↗