A.N. Legeyda, candidate                                                                                   
N.N. Schemenok, candidate                               
V.N. Seluyanov, professor, Ph.D.
Russian state university of physical culture, sport, youth and tourism, Moscow

Key words: aerobic exercises, aerobic threshold, intensity, anaerobic threshold, sphygmogram, cholesterol, cardiovascular system

Introduction. In sports practice training at the level of aerobic threshold (AeT) is performed for the activation of fat metabolism, and training at the level of anaerobic threshold (AnT) to improve the aerobic capacities of the body of probands [1]. However, the impact of these loads on women of the second period of mature age has been insufficiently studied, in particular, the studies proving the effects of such load on the vascular system and blood triglycerides are lacking.

Hypothesis. Performance of aerobic exercises with the intensity at the level of AnT should lead to a statistically significant increase of aerobic fitness. Performance of aerobic exercises with the intensity at the level of AeT is to render a positive effect on blood triglycerides, help to reduce the viscosity of the aortic compression chamber due to the decrease in fat mass in the surrounding tissues.

Experiment.

Female students of the technical university were involved in the experiment. Changes in the indicators of the cardiovascular system were studied in physically active, healthy women under the influence of aerobic exercises of various intensity levels. The age of the subjects was 20.5 ± 0.3 years, height - 165 + 4 cm, weight - 66 ± 3.5 kg.

The subjects involved in the experiment were divided into two groups. The first group (N = 10) had been doing training exercises of continuous run at the level of the aerobic threshold for 2 months. The training sessions were held 3 times a week 45 minutes each. The second group (n = 10) had been doing training exercises in the form of continuous run at the level of anaerobic threshold for 2 months. Like in the first group, the training sessions were held 3 times a week 45 minutes each.

All of the subjects were examined in vitro before and after the experiment. The examination included:

1) Step test on the Monark 827 bicycle ergometer. In this test the МЕТАМАХ gas analyzer was used to determine: carbon dioxide production, oxygen uptake, pulmonary ventilation, heart rate (HR). The test lasted up to MOC (maximal oxygen consumption).

2) Prior to the step test sphygmogram indices were determined using the Pulse Trace PCA 2 device (UK). The device works based on the theory of reflection and pulse wave propagation. The pulse wave data is recorded by a plethysmography sensor - highly sensitive photoelectric cell. Further the digital wave is subject to a loop analysis.

3) The CardioChek device was applied to determine blood cholesterol. The low-density lipoprotein (LDL) and high-density lipoprotein (HDL) blood concentration was examined.

In order to analyze the data obtained using the device Pulse Trace PCA 2, we additionally introduced our calculated values​​ for the most accurate analysis of sphygmograms of the probands.

It has been suggested using:

1) the index of oscillation frequency of the aortic wall (Fa) in Hz, in order to evaluate the elasticity of aortic compression chamber (ACC).

 Fa=1/PPT*1000, where PPT - time in milliseconds, as measured between two peaks of the sphygmogram.

2) the rate of transport of blood to great vessels of the aortic compression chamber (or peripheral resistance).

Flex= H2/H1*100%, where H2 - the height of the second peak on the sphygmogram, H1- height of the first peak on the sphygmogram.

3) Viscosity of ACC.

StACC = Hmin/H2*100%, where Hmin – height of depression on the sphygmogram, in other words the minimum between two peaks, H2 - height of the second peak on the sphygmogram.

Results and discussion. The results of the educational experiment are shown in Table. It can be seen that MOC is within 30-35 ml/min/kg, which corresponds to the satisfactory level of development of aerobic capacities of women. Oxygen uptake at AnT was 68-88% at HR 165-172 bpm. The oscillation frequency of ACC increased slightly, and viscosity, i.e. the intensity of oscillation decay, decreased, which, as we believe, indicates an improvement in the aortic wall and its removal from the surrounding tissues (fat). The indicators of blood triglycerides improved due to the increase of HDL blood concentration and the decrease of LDL.

As follows from the analysis of the findings, when training at AeT (aerobic threshold) a statistically significant change occurred in the sphygmogram indicators - viscosity of aortic compression chamber (ACC), as well as an increase of the HDL concentration, which is an indicator of improving triglyceride blood count.

When training at the level of AnT (anaerobic threshold) statistically significant differences in the increase in oxygen uptake at AnT and the index of viscosity of ACC were determined.

All other changes in the examined indicators were not statistically significant.  

Table. Changes in the indicators of the status of the cardiovascular system and physical working capacity after aerobic exercises of different intensity levels.

Conclusions:

1) Training at the level of AeT leads to a statistically significant change in such an index of the sphygmogram as viscosity of ACC and an increase of HDL blood concentration, which generally indicates an improvement in blood triglycerides.

2) Performance of aerobic exercises at the intensity of AnT significantly increases the level of aerobic fitness and decreases viscosity of ACC.

3) Training sessions at the levels of AeT and AnT promoted a significant reduction of the number of abnormal sphygmograms, which shows the improvement of the indicators of arterial system in general. However, the results of the experimental group were higher than in the control one.

5) MOC is within 30-35 ml/min/kg, testifying to the satisfactory level of development of women's aerobic abilities. Oxygen uptake at AnT was 68–88 % with HR 165–172 bpm. The oscillation frequency of ACC increased slightly while viscosity, i.e. intensity of oscillation decay, decreased, which as we assume, proves the improvement of aortic wall and removal of surrounding tissues (fat) from it. The indicators of blood “triglycerides" improved owing to the increased HDL blood concentration and the decreased LDL.

References

1. Volkov, N.I. Biochemistry of muscular activity / N.I. Volkov, E.N. Nesen, A.A. Osipenko, S.N. Korsun. – Kiev: Olimpiyskaya literatura. – 2000. – 503 P. (In Russian)

Corresponding author: shulenkova-l@mail.ru