The potential maximum oxygen consumption as an indicator of maximum cardiac output

 Translated from Russian

Gavrilov VB, Shcherbakov, VA, and VN Seluyanov
Research Institute of Sports RGUFKe

Introduction

The test with stepwise increasing capacity is central to the definition of physical fitness of athletes of many sports. According to the changes in heart rate (HR), pulmonary ventilation (Ve), power (W), oxygen consumption (VO 2 ), carbon dioxide (V CO2 ) and the concentration of blood lactate (La) determine the values ​​corresponding to the thresholds of aerobic and anaerobic metabolism and IPC.
The test rate of pedaling is supported by 60 or 75 rev / min. In this case, when the resistance of the athlete must recruit more and more muscle fibers. While he recruits oxidative muscle fibers in heart rate and LV vary in a linear relationship. Since the beginning of the recruitment of glycolytic muscle fibers, there is lactate, hydrogen ions, and hence the excess carbon dioxide. Excess CO 2 causes an additional activation of the heart and respiratory muscles. The kinks in the curve 'lung ventilation - power (oxygen consumption) "allow us to determine parameters of capacity, oxygen consumption for ventilation aerobic and anaerobic thresholds.

Hypothesis

It has long been observed that when tested with a low rate quickly begins to attack the local muscle fatigue, so cyclists are tested at a rate of 90 rev / min. Local fatigue is associated with the accumulation of lactic acid, which is formed in the muscle fibers recruited. Glycolytic muscle fibers are recruited only at a certain external resistance (internal work intensity), so with a lower resistance when only oxidizing recruited muscle fibers, increasing the rate of pedaling can be made to produce high mechanical and metabolic capacity of oxidative muscle fibers, since the metabolic capacity of mitochondria in them should match the power of ANP. Consequently, when pedaling with a high rate of aerobic and anaerobic thresholds have to approach each other or coincide, and the real maximum oxygen consumption has substantially increased, since a reduction of blood acidification will reduce the degree of activation of the SSA and the DS.

Methodology

In the experiment, took part in nine athletes (skiers and athletes) from the second level to the masters of sports of international class. All athletes have measured the mass and body length. Each subject participated in three experiments:

  • 1) Test stepwise at a rate of 75 rev / min, the duration of stage 2 min., The load was varied from 5 h (0.5 Cr).
  • 2) After 30-60 minutes. then the second step rate test with 120 rev / min, 2 min duration of the step, the load is changed to 2.5 N (0.25 Cd).
3) In the third experiment measured the maximum alaktatnuyu power output was measured in a sprint on the cycle ergometer with an external resistor ( power = 0,8 × body weight, H).In the course of experiments on the bicycle "Monark" heart rate were measured using pulstestora POLAR-810 lung ventilation using the "VOLID-900".

Results

In Table. 1 presents estimates of the physical development of the subjects. It is seen that an increase in the rate of 120 rev / min in these figures AEP subjects 120 and API 120, as well as the INCD 75 and 120 MPKr coincide.
Table 1. Indicators of physical development and physical fitness of subjects (sample size 9).


Indicators The average Environments. square. Off
Age, y 18.8 4.0
Body weight, kg 68.1 8.2
Length of body, cm 177 7.0
MAM, W / kg 11.8 1.0
AEP 75 W / kg 2.2 0.4
ANP 75, W / kg 3.8 0.8
AEP 120 W / kg 4.4 0.6
ANP 120 W / kg 4.4 0.6
IPC real 75 ml / min / kg 54.7 8.2
P 75 of the IPC, W / kg 4.07 0.7
IPC potential 75 ml / min / kg 69.0 11.2
IPC n 75, W / kg 5.17 0.95
IPC real 120 ml / min / kg 69.0 11.2
P 120 IPC, W / kg 5.17 0.95

The reason for such a close match can be understood from the experimental data presented in Figure 1. It is seen that the curve "in heart rate - external power (Wex)» for the rate of 75 rev / min there is a fracture, which corresponds to the aerobic threshold, then there is a second turning point and he is identified as the anaerobic threshold by the method of Vasermana (Waserman, 1984). The line "HR - external power" for the rate of 120 rev / min is higher, but part of the energy expended to move the legs (Win). Calculate this capacity can be according to Seluyanova VN Saveliev and IA (1982), but you can experiment, if we compare the power developed at a pulse rate at 75 and 120 rev / min. In this case, the power to move the legs was 120 watts. With this amendment, the line was built, "HR - (Wex + Win)", which just laid down on the continuation of the initial section dependence, "HR - Win» for the rate of 75 rev / min. In this case, we have the coincidence of power on the pulse of 190 beats / min, as in the case of a test with 75 rev / min, and for the rate of 120 rev / min. If these indicators are defined as the potential for 75 of the IPC r / min and the MIC for the real rate of 120 rev / min, we can assume that in the test with 75 rev / min can not determine a real opportunity to deliver oxygen to the muscles of the cardiovascular system in terms of the potential of the IPC . IPC River averaged 79% of the INCD. One can also note that at the level of ANP in the rate of 120 rev / min was fixed power greater than the level of ANP in testing at a rate of 75 rev / min, and the magnitude of the pulmonary ventilation of us chosen to be in both cases. This power was on average higher than the actual IPC.

Figure 1. Experimental data survey athlete 16 years in step with the rate of 75 tests and 120 rev / min.

Output

When comparing the relationships between heart rate and power of the tests of step with the rate of 75 and 120 rev / min, it was shown that the lines are superimposed on each other until the onset of anaerobic threshold. According to the schedule of this line, you can define the potential of the IPC, which should be in relatively pure form, characterized by the potential of the cardiovascular system to deliver oxygen to the muscles.

Literature

Seluyanov VN Savel'ev, IA Internal mechanical work of pedaling on the cycle ergometer. Human Physiology, 1982, 8, 2. S. 235 240.
Wasserman K. The anaerobic threshold measurement to evaluate exercise performance. / / Am. Rev. Respir. Dis. Suppl. - 1984. - 129. - P. 35 - 40.

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