PhD, Associate Professor R.G. Ardeev¹
PhD, Associate Professor T.I. Gornaya¹
PhD, Associate Professor E.A. Evsetsova¹
PhD, Associate Professor Yu.V. Sirenko²
PhD, Associate Professor R.R. Fattakhova^2
1Birsk branch of Bashkir State University, Birsk
²Eastern Academy of Economics, Law and Humanities (VEGU Academy), Ufa

Keywords: physical workload, heart rate, minute blood stroke, blood pressure.

Introduction. The main role in the adaptation of the body to functional tests belongs to the cardiovascular system, which is an integral part of the adaptation problem. To preserve the optimal state of the body, the cardiovascular system is to adequately distribute the blood to the blood vessels. Currently, a large number of physical activities are used in rehabilitative physical education, including passive pedaling on a bicycle ergometer (robotic mechanotherapy) (R.G. Ardeev, N.N. Shayakhmetov, L.R. Shayanurova, 2017; Yu.S. Vanyushin, N.N. Shayakhmetov, R.G. Ardeev, 2014; N.N. Shayakhmetov, Yu.S. Vanyushin, R.G. Ardeev, 2013; O. Pogarell et al., 2002; J.C. Moller et al., 2005; C.D. Takahashi, L. Der-Yeghiaian, V. Le, R.R. Motiwala, S.C. Cramer, 2008; A. Ridgel, J.L. Vitek, J.L. Alberts, 2009; Waldemar Diehl, 2010); pedaling on a bicycle ergometer in the non-resisted cycling mode, i.e. when the external load power is equal to 0 W and low-intensity physical load itself ranges within 0.25-0.5 W/kg.
An important aspect of physical rehabilitation is adequate physical workloads on the human body; this fact is especially important in case of more serious pathologies of the cardiovascular system (CVS). Herewith, the physiological mechanism of adaptation of the body is of no small importance.
Objective of the study was to analyze the cardiovascular system responses to the low-intensity functionality tests in the 22-29-year-old males.
Methods and structure of the study. The sample of 22-29 year old males (n=41) was tested by the cycle ergometer tests at 0.25 W/kg in the passive (motor-assisted) and non-resisted cycling modes. The cardiovascular system adaptation mechanisms were analyzed using the three-polar chest rheography. Every subject was tested in a quiescent state (Table 1) and then by passive cycling tests in two work modes followed by the functionality tests. The tests were run on different days.
Results and discussion. The study showed that regardless of the functionality test rates, there was an increase in the subjects’ haemodynamics rates (Table 2).

Table 1. Cardiovascular system functionality rates at rest (М±m)

Note: * – as compared to the previous measurements; ○ – in-between pedaling in the non-resisted (0 W) and passive (motor-assisted) cycling modes; ″ - in-between the passive cycling and physical workload of 0.25 W/kg;

The maximal dynamics was observed under the load of 0.25 W/kg. When pedaling in the non-resisted and passive cycling modes, in contrast to that under load of 0.25 W/kg, HR increased slower. Under the low-intensity loads, we could observe a more economic functioning of the cardiovascular system. This can be explained by the fact that cardiac activity is secured by the local and self-regulatory mechanisms of regulation. Probably, the central circuit of regulation of blood circulation is activated during heavy physical loads.
Minute blood stroke is formed owing to the greater contribution of stroke volume (SV). The greatest increase in SV was recorded under the load of 0.25 W/kg, the minimal – during the passive cycling.
The increase in the minute blood stroke at 0.25 W/kg is understandable. It is due to the fact that the oxygen demand increases, so does the venous return as a result of enhanced exposure of the skeletal muscles on the blood vessels. Under physical loads, the muscular system, together with the vessels, works like a pump, increasing the venous return. The more frequent and more active the movement, the more effective the impact of the muscles on the venous return. The differences between the minute blood stroke rates at 0.25 W/kg and 0 W/kg are understandable. When the pedals rotate in the absence of any external resistance, the skeletal muscles encounter zero braking. However, the increase in the haemodynamics rates is due to the muscle contraction occurring at the time of initial acceleration and achievement of the necessary cadence. The minute blood stroke during the passive cycling increases; in our opinion, here, there is no active effect on the formation of the venous return in the skeletal muscles.
Under the influence of physical loads, the reflex-compensatory phenomenon is that there is a decrease in the tone of the peripheral vascular resistance. This process makes it possible to normalize blood pressure in response to the increase in the minute blood stroke. It should be noted that during exercise it is the decrease in the total peripheral vascular resistance that is most pronounced, which is normally manifested 5-10 s into the muscle work, and reaches its maximum in 1 min. At 0.25 W/kg, we registered the highest values of the minute blood stroke (more than 100%). When pedaling in the non-resisted cycling mode (0 W), the minute blood stroke increases by 40%. At the same time, blood pressure remains at the same level, which is not typical for the load of 0.25 W/kg (increased blood pressure is noted). The comparison of the absolute values of the total peripheral vascular resistance at the end of the functional test (between the 6th and 9th min) revealed the difference of 310-340 dyne cm-5s. A slightly different response of the vascular system was observed during passive cycling. In contrast to the previous functionality test, namely, their completion, there was a tendency towards a decrease in the blood pressure. This is due to the fact that with increased minute blood stroke, the maximum decrease in the tone of the total peripheral vascular resistance is possibly due to the absence of reflex tension of the walls of the venous vessels. This kind of reaction of the vascular system makes it possible to create the necessary conditions for a decrease in the blood pressure during the test, namely, by its completion. Along with the above, we detected a decrease in the heart rate and an increase in the period of blood ejection out of the heart. Probably, this kind of favorable cardiovascular system response is associated with an "unstimulated systole".
Consequently, the findings of the study testify to the multidirectional nature of the cardiovascular system response to the functionality tests of low power. Of particular interest is the passive pedaling on the bicycle ergometer due to the original motor rotating at the speed of 60 rpm. The absence of muscle tension in the process of adaptation to the functionality tests leads to the maximal decrease in vascular tone as well as a decrease in blood pressure. This type of reaction allows using this kind of test for the purpose of rehabilitation of people diagnosed with the cardiovascular system pathologies.
Conclusion. The study showed significant differences in the cardiovascular system responses and central haemodynamics rates in the sample – that may be interpreted as differences in the cardiovascular system responses to the low-intensity physical workloads. Of special interest for the study purposes were the passive motor-assisted cycling tests rated at 60 rotations per min – free of serious muscle stresses in the adaptation process associated with reductions in the vascular tonus and blood pressure. These tested responses expand our knowledge of the natural physiological responses to the low-intensity physical workloads and may open up new opportunities for the rehabilitation service and special controlled physical training models.

References

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Corresponding author: Even78@inbox.ru

Abstract
The main role in the adaptation of the body to functional tests belongs to the cardiovascular system, which is an integral part of the adaptation problem. To preserve the optimal state of the body, the cardiovascular system is to adequately distribute the blood to the blood vessels. The article analyzes the cardiovascular system responses to the low-intensity functionality tests in the 22-29-year-olds. The sample was tested by the cycle ergometer tests at 0.25 W/kg in the passive (motor-assisted) and non-resisted cycling modes. The cardiovascular system adaptation mechanisms were analyzed using the three-polar chest rheography. Every subject was tested in a quiescent state and then by passive cycling tests in the two work modes followed by the functionality tests.
The study showed significant differences in the cardiovascular system responses and central haemodynamics rates in the sample – that may be interpreted as differences in the cardiovascular system responses to the low-intensity physical workloads. Of special interest for the study purposes were the passive motor-assisted cycling tests rated at 60 rotations per min – free of serious muscle stresses in the adaptation process associated with reductions in the vascular tonus and blood pressure. These tested responses expand our knowledge of the natural physiological responses to the low-intensity physical workloads and may open up new opportunities for the rehabilitation service and special controlled physical training models.