Abstract des Autors

The aim of the article is to present an overview of scientific research concerning
changes of heart rate during stay in the aquatic environment and to analyze causes of these changes. A literature search was performed using SportDiscus, Medline and Web of Science using the key words heart rate, water temperature, water immersion, bradycardia. The individual heart rate during immersion and exercise in water is affected by water temperature, depth of the water, buoyancy, posture of the body in the water, the dive reflex and the heart rate in rest. Marked changes occur in the body`s circulatory system and temperature regulating mechanisms, which subsequently influence other bodily functions. The effect of the water environment begins immediately upon immersion, so physiological changes occur quickly.
The mechanism responsible for the lower heart rate during immersion is the
redistribution of blood volume from the periphery to the central region. The increased hydrostatic pressure of the water, concomitant with peripheral vasoconstriction to reduce heat loss forces peripheral blood into the thorax. For determining target heart rate zone for water activities we recommend to use Kruel`s protocol and Karvonen`s formula. The most accurate way of measuring maximal heart rate (HRmax) is via a cardiac stress test. However measuring HRmax in this manner is not available for general population, therefore we recommend to use Inbar`s equation: HRmax = 205,8 – (0,685 x age). Verf.-Referat