PhD A.V. Kabachkova¹
Master's student V.V. Kologrivova¹
S.S. Frash²
Dr.Med., Professor L.V. Kapilevich^{1, 2
1}National research Tomsk state university, Tomsk
²National research Tomsk polytechnic university, Tomsk

Keywords: running, walking, rheovasography, regional blood flow, correlation analysis, workload time, cardiovascular system.

Introduction. The circulatory reaction to muscular load is due to adaptive adjustments in both central and peripheral hemodynamics [2, 6]. Herewith, peripheral circulation can serve as a factor limiting muscular endurance [1, 4]. During exercise the functional status of blood vessels changes, which is conditioned by both central [7] and local regulatory factors [8] and is directed to facilitate cardiac performance, as well as to improve blood supply to the muscle groups involved in work [3, 5].

Objective of the study was to determine the key regularities of the lower-limb peripheral blood circulation responses in healthy untrained men being subject to the tests by graded physical loads.

Methods and structure of the study. Subject to the study were healthy untrained men aged 17-20 years (n=25). The graded physical load involved walking (average pace - 120 steps/min) and running (average pace - 180 steps/min) for 15 minutes. The movement pace was set by a metronome. The lower-limb blood circulation (upper and lower thirds of the leg, ankle) was assessed using the software module "Rheography" as part of the hardware and software complex "Valenta" (LLC "Neo Company", Russia). Blood pressure was measured using the OMRON tonometer (JSC " KomplektService ", Russia), heart rate (HR) - using the GARMIN heart rate monitor, and the levels of peripheral oxygen saturation (SpO2%) – using the Sigma PC15.11 pulse oximeter.

The effect of stress factors, related to exams and assessments, was excluded. The survey was conducted in the morning hours. At the baseline, all subjects had no acute or chronic diseases in past medical history.

The data were statistically processed using the STATISTICA 8.0 software and were supplemented by the correlation analysis results. P≤0.05 was taken as a statistically significant difference.

Results and discussion. Graded running loads. More pronounced variations of blood flow rates against the background of load at all levels were registered in the take-off leg, in contrast to the supporting one, where the variations were registered only at the level of the ankle. The more continuous the load, the more pronounced the increase in the tone of the distributing vessels (r=0.51, p<0.05) and resistance vessels on the right (r=0.50, p<0.05). Vascular tone increases at the level of popliteal artery, arteries of the knee (lateral superior and inferior, medial superior and inferior), posterior and anterior tibial arteries. Against the background of increasing vascular tone, there exists a blood filling difficulty in the lower-limb muscles and a venous outflow difficulty (r=-0.5, p<0.05) at the level of the lower tibial vein, large popliteal vein, posterior tibial vein and small saphenous vein. The graded running loads merely in the left ankle provide changes in the tone of the resistance vessels, venous return and capacitance vessels (r=0.50, p<0.05). By the end of the 15th minute of running load the tone of the resistance vessels decreases and venous outflow becomes normal.

Under running load a direct correlation was found between the tone of the small vessels (at the level of the upper and lower thirds of the leg) and heart rate (HR) performance, and reverse correlation - between the indicators of the elasticity and tone of the large vessels, venous outflow and heart rate. Herewith, the HR values reached 60% of the maximum.

At the 3rd minute of running load there takes place a decrease in the peripheral saturation to the level of 95%, and at the 9th minute – formation of a stable hypoxic state (with downward trend at the linear approximation). There was also observed a direct correlation between SpO2 and elasticity of the medium and small arteries (r=0.50, p<0.05), precapillaries (r=0.50, p<0.05) and postcapillaries (r=0.50, p<0.05) on the left. At the same time, a reverse correlation was detected between SpO2 and elasticity of the large (r=-0.50, p<0.05) and medium (r=-0,.51, p<0.05) arteries of the lower third of the leg arteries on the right, venous outflow on the left  (r = -0,54, p <0,05), as well as the level of blood filling in the left ankle (r=-0,.86, p<0.05).

Graded walking loads. Under step load there is an increase in the tone of the distributing vessels and resistance vessels at the level of the upper third of the leg on the right and on the left. Against the background of increasing vascular tone venous outflow decreases, which is especially pronounced at the level of the lower third of the leg on the left. Dosed walking leads to an increase in blood filling at the level of the ankle on the right and on the left (r=0.70, p<0.05).

SpO2 value was at the level of 95-97% versus the baseline level (the trend line is parallel to the absciss axis). At the 7th and 14th minutes the maximum saturation was at the level of 97%. The HR values reached 40% of the maximum. We detected a direct correlation between the blood filling rates of the lower third of the leg (r=0.52, p<0.0 5), elasticity of the large vessels of the upper third of the leg (r=0.50, p<0.05) and SpO2 level. The reverse correlation was found between the venous outflow values (r=-0.50, p<0.05) and SpO2 level. All these correlations were determined for the left leg (in all subjects the right leg is the leading one).

The dosed walking revealed a direct correlation between the indicators of the elasticity and tone of the small vessels, blood filling and HR performance, and reverse correlation between the indicators of the elasticity and tone of the large vessels and HR performance.

Conclusion. The locomotor system loads are associated with variations of many peripheral hemodynamic system performance rates indicative of the tonuses of the large and small vessels, blood inflow and venous outflow in the lower-limb muscles. When performing graded running exercise, the changes in the indices of the take-off (right) leg are registered at all levels (upper and lower thirds of the leg, ankle), while similar changes in the left leg occurred only at the level of the ankle. Dosed walking caused symmetrical changes in the rheovasographic indicators at all levels.

The detected correlations of the rheovasographic indicators with durations of the graded physical loads and variations of the central hemodynamic characteristics may be due to interdependent settings of the central and peripheral (local) regulatory mechanisms. The latter may contribute to the working capacity reserve building process through the blood flow being redistributed in favour of the working muscle groups involved in the locomotor activity.

References

1. Arshinova N.G., Vikulov A.D., Botin A.I. Sopryazhennost fiziologicheskikh mekhanizmov regulyatsii serdechnoy deyatelnosti i krovetvoreniya u sportsmenov [Conjugation of physiological mechanisms of regulation of cardiac activity and hematosis in athletes]. Vestnik YuUrGU, 2009, no. 27, pp. 26-27.
2. Baranova E.A., Kapilevich L.V. Funktsionalnaya adaptatsiya serdechno-sosudistoy sistemy u sportsmenov, treniruyushchikhsya v tsiklicheskikh vidakh sporta [Functional adaptation of cardiovascular system of cyclic athletes]. Vestnik Tomskogo gos. un-ta, 2014, no. 383, pp. 176-179.
3. Kabachkova A.V., Frolova J.S., Dmitrieva A.M., Bulgakova A.I., Duras E.E., Fomichenko V.V. Izmenenie krovotoka nizhnikh konechnostey u voleybolistov pri vypolnenii odnomomentnoy funktsionalnoy proby [Changes in lower limb blood flow in volleyball players during simultaneous functional test]. Vestnik Tomskogo gos. un-ta, 2014, no. 388, pp. 219-222.
4. Kologrivova V.V., Kabachkova A.V. Perifericheskaya kislorodnaya saturatsiya pri vypolnenii dozirovannoy fizicheskoy nagruzki [Peripheral oxygen saturation under graded physical load]. Mater. X Mezhdunar. nauch.-prakt. konf., posvyashchennoy pamyati V.S. Pirusskogo "Fizicheskaya kultura, zdravookhranenie i obrazovanie" [Physical education, health care and education: Proc. X Intern. res.-pract. conf. in memory V.S. Pirussky]. Tomsk: STT publ., 2016, pp. 239-243.
5. Popova I.E., Germanov G.N., Tsukanova E.G. Osobennosti regionalnoy gemodinamiki u legkoatletov-begunov na srednie distantsii [Characteristics of regional hemodynamics in middle distance runners]. Uchenye zapiski un-ta im. P.F. Lesgafta, 2010, no. 2 (60), pp. 104-112.
6. Kabachkova A.V., Frolova Yu.S., Kapilevich L.V. Reaktsiya regionarnogo krovotoka nizhnikh konechnostey na step-ergometricheskuyu nagruzku u sportsmenov [Reaction of Lower Limb Regional Blood Flow to Step Ergometric Load in Athletes]. Teoriya i praktika fiz. kultury, 2014, no.10, p. 16.
7. Koshel’skaya E.V., Razuvanova A.V. Smerdova O.S. et al. Upravlenie sportsmenami polozheniem tela v prostranstve v faze poleta [Athletes body position control in flight phase]. Teoriya i praktika fiz. kultury, 2014, no. 12, pp. 47-49.
8. Kapilevich L.V., Kovalev I.V., Baskakov M.B. Intracellular signal systems in the epithelium- and endothelium-dependent relaxation of smooth muscles. Uspekhi fiziologicheskikh nauk, 2001, vol. 32, no. 2, pp. 88-98.

Corresponding author: kapil@yandex.ru

Abstract

The study tested and analyzed the key regularities of the lower-limb blood circulation system responses, with healthy untrained men aged 17-20 years being subject to the tests by graded physical workloads. The study found the locomotor system loads being associated with variations of many peripheral hemodynamic system performance rates indicative of the tonuses of the large and small vessels, blood inflow and venous outflow. The study found a few correlations of the blood flow rates with durations of graded physical loads, with the variations of the central hemodynamic characteristics being probably due to the interdependent settings of the central and peripheral (local) regulatory mechanisms. The latter may contribute to the working capacity reserve building process through the blood flow being redistributed in favour of the working muscle groups.