Cardiovascular Adjustments during Graded Exercise Stress

Abstract

Research background and hypothesis. Cardiac function provides an adequate blood supply to all organs thus
changes in the performance and functional state of cardiac muscles during exercising are very important.
Research aim. The aim of the study was to find out the peculiarities in adjustment of cardiovascular system in
dependence on the type of adaptation to physical loads during graded stress.
Research  methods.  The  study  participants,  17  non-athletes,  23  endurance,  19  sprint  and    21  combat  sport
athletes, underwent a bicycle ergometry of incremental increase in provocative workload (graded stress). A 12-lead
ECG was reordered and a computerized program allowed to measure ECG parameter, the ratio of JT/RR intervals
and the velocity of adaptation of cardiovascular system to exercising (V Ad ), by calculating the difference between the
relative changes of JT interval and RR interval as a difference: V Ad . = (JTi/JT0) 100% – (RRi/RR0) 100%.
Research results. No significant functional ischemia was found in endurance cohort during the graded stress
while it was expressed in non-athletes’ cohort and slightly smaller in sprint and combat cohorts. Maximal values of
other ECG or ABP parameters registered during graded stress did not reveal significant differences between cohorts.
Discussion  and  conclusions.  Functional  ischemia  is  an  important  factor  limiting  muscular  and  cardiac
performance during the graded exercise stress. The exercise type plays a significant role in developing the velocity of
adaptation of cardiovascular system at onset of exercising. Faster adaptation at onset of exercise is more characteristic
of sprint and combat sports than representatives of endurance or non-athletes.

Keywords: cardiovascular system, adaptation, functional ischemia.