Central hemodynamic response rates and baroreflectory sensitivity of vascular resistance rates in athletes taking caffeine at rest

Фотографии: 

ˑ: 

Dr.Biol., Professor R.V. Tambovtseva1
PhD, Associate Professor V.R. Orel1
O.V. Zhumaev1
Russian State University of Physical Education, Sport, Youth and Tourism (GTSOLIFK), Moscow

 

Keywords: central haemodynamics, peripheral and elastic resistance rates, dose, blood pressure, heart rate, physical work, fatigue rate, caffeine.

Introduction. Objective patterns of changes in central haemodynamics in athletes are important for proper understanding and describing the processes of formation of blood pressure and heart rate (HR) values which are the main non-invasively measured indices of the circulatory system. At the same time the cardiovascular system of an athlete [7] is the main factor that limits the body’s functional capabilities that ensure required amount of physical work performed by the athlete. 

The interaction of the heart and blood vessels is determined both by the contractility level of the left ventricle of the heart [1, 9, 10] and the state of its vascular load [4, 5, 8, 9], as well as by the baroreflectory regulation properties of the circulatory system [3, 4] which together form the central haemodynamics and cardiac cycle phase structure indices.

The study objective was to reveal the dependence of the elastic resistance of the arterial system on the peripheral resistance and the level of fatigue before and after caffeine intake at a dose of 4 mg/kg, 7 mg/kg and 10 mg/kg.

Research methods and structure. Blood pressure was measured auscultatory. The rheogram of the central pulse was continuously recorded using the tetrapolar rheography method [6]. The measurements for each subject were made sequentially in the sitting, standing and sitting positions immediately after entering the blood pressure measurement results into the computer. Measurements of central haemodynamics indices in the athletes (n=23) were performed while at rest.

The study data archived in REODIN-504 System included HR data, stroke volume, heart cycle phases and blood pressure. These input data were applied to compute the elastic (Ea) and peripheral (R) resistance of the arterial system [8, 9].

A new parameter F [4] was also used in the study, calculated for each subject based on the set of vascular resistance values. It can be characterized either as athlete's fatigue rate or as a possible positive effect of a training session.   

The effect of different caffeine doses on the haemodynamic response in the athletes during recovery after exercises was considered.

Results and discussion. Athletes' cardiac hemodynamic data obtained before caffeine intake and 20-30 minutes after it at the dose of 4 mg/kg show that HR, Еа and F significantly decrease after the caffeine intake, and the values of Ps, Pd, R, SV and MV significantly increase.

Figure 1 shows the dependence of the elastic resistance (Еа) of the arterial system on the peripheral resistance (R) before caffeine intake and 20-30 minutes after it (Figure 1).

 

Figure 1. Relationship between elastic resistance (Еа) of the arterial system and peripheral resistance (R) before caffeine intake (○) and after it (∆) at a dose of 4 mg/kg

The abscissa – peripheral resistance (R), dyn·s·cm−5

The ordinate – elastic resistance (Еа), dyn·s·cm−5

The bulk of the data before the caffeine intake is located strictly above the Ea data measured after the intake. At the same time the slope coefficient F of the regression relationship between Ea and R is 1.95 before the intake, and after the intake the coefficient becomes significantly lower: 1.196, which indicates a certain decrease of fatigue in athletes after the caffeine intake at a dose of 4 mg/kg.

Before the caffeine intake the peripheral resistance varied from 830 to 1,370 dyn·s·cm−5, and elastic one – from 700 to 1,620 dyn·s·cm−5.

After the caffeine intake the peripheral resistance varied from 700 to 1,400 dyn·s·cm−5, and elastic one – from 700 to 1,350 dyn·s·cm−5.

The coefficients of correlation between R and Ea both before and after the intake shown in Figure 1 are positive (the increase in R is accompanied by an increase in Ea) and also statistically significant (p < 0.001).

Cardiac hemodynamic data of athletes obtained before the caffeine intake and 20-30 minutes after it at the dose of 7 mg/kg show that HR, Ps, Еа, R and F significantly decrease after the caffeine intake, and the values of Pd, SV and MV significantly increase.

Figure 2 shows the relationship between the elastic resistance (Еа) of the arterial system and the peripheral resistance (R) before the caffeine intake and 20-30 minutes after it (Figure 2).

 

Figure 2. Relationship between elastic resistance (Еа) of the arterial system and peripheral resistance (R) before caffeine intake (○) and after it (∆) at a dose of 7 mg/kg

The abscissa – peripheral resistance (R), dyn·s·cm−5

The ordinate – elastic resistance (Еа), dyn·s·cm−5

The bulk of the data before the caffeine intake is located strictly above the Ea data measured after the intake. At the same time (Table 2) the slope coefficient F of the regression relationship between Ea and R is 1.31 before the intake, and after the intake the coefficient becomes significantly lower: 0.7698, which indicates a certain decrease of fatigue in athletes after the caffeine intake at a dose of 7 mg/kg.

Before the caffeine intake the peripheral resistance varied from 1,230 to 2,180 dyn·s·cm−5, and elastic one – from 1,250 to 2,600 dyn·s·cm−5.

After the caffeine intake the peripheral resistance varied from 1,150 to 2,140 dyn·s·cm−5, and elastic one – from 1,000 to 2,000 dyn·s·cm−5.

The coefficients of correlation between R and Ea both before and after the intake shown in Figure 2 are positive (the increase in R is accompanied by an increase in Ea) and statistically significant (p < 0.001).

Cardiac hemodynamic data of athletes obtained before the caffeine intake and 20-30 minutes after it at the dose of 10 mg/kg show that HR, Еа, MV and F significantly decrease after the caffeine intake, and Ps, Pd, R and SV values significantly increase.

Figure 3 shows the relationship between elastic resistance (Еа) of the arterial system and peripheral resistance (R) before the caffeine intake and 20-30 minutes after it (Figure 3).

 

Figure 3. Relationship between elastic resistance (Еа) of the arterial system and peripheral resistance (R) before caffeine intake (○) and after it (∆) at a dose of 10 mg/kg

The abscissa – peripheral resistance (R), dyn·s·cm−5

The ordinate – elastic resistance (Еа), dyn·s·cm−5

The bulk of the data before the caffeine intake is located strictly above the Ea data measured after the intake. At the same time the slope coefficient F of the regression dependence of Ea on R is 1.365 before the intake, and after the intake the coefficient becomes significantly lower: 0.218, which indicates a certain decrease of fatigue in athletes after the caffeine intake at a dose of 10 mg/kg.

Before the caffeine intake the peripheral resistance varied from 610 to 1,080 dyn·s·cm−5, and elastic one – from 620 to 1,260 dyn·s·cm−5.

After the caffeine intake the peripheral resistance varied from 750 to 1,240 dyn·s·cm−5, and elastic one – from 650 to 1,080 dyn·s·cm−5.

The coefficients of correlation between R and Ea both before and after the intake shown in Figure 3 are positive (the increase in R is accompanied by an increase in Ea) and also statistically significant (p < 0.001).

It is characteristic that in all the three tables almost all the differences between the haemodynamics indices in the columns “before the caffeine intake” and “after the caffeine intake” are statistically significant, since the number of cardio cycles  processed while calculating the mean values presented in the tables is at least 200.

At the same time, in Table 2 the absolute value differences between the mean values of HR, systolic blood pressure and diastolic blood pressure are rather small, and the differences between the other indices in different tables change their direction. 

The decrease in the baroreflectory sensitivity coefficient F between the peripheral and elastic resistance of the arterial system remains unchanged in all cases.

Conclusions:

  • In all cases of caffeine intake a statistically significant HR reduction takes place 20-30 minutes after it. 
  • In all cases of caffeine intake a statistically significant growth of the stroke volume (SV) takes place 20-30 minutes after it.
  • In all cases of caffeine intake a statistically significant reduction of the baroreflectory sensitivity coefficient F for the peripheral versus elastic resistance rates of the arterial system takes place 20-30 minutes after it.  

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Corresponding author: ritta7@mail.ru

Abstract

Objective of the study was to profile the haemodynamic response rates in the athletes taking varying doses of caffeine in recovery periods following physical loads. Subject to the experiment were 23 highly skilled athletes from different sport disciplines. The study data archived in REODIN-504 System included HR data, stroke volume, heart cycle phases and blood pressure. These input data were applied to compute the elastic (Ea) and peripheral (R) resistance of the arterial system. The study data and analyses showed statistically significant changes 20-30 minutes after the caffeine intake including the following: significant HR reduction; significant growth of the stroke volume (SV); and significant reduction of the baroreflectory sensitivity for the peripheral versus elastic resistance rates of the arterial system.