Abstract: In order to reduce the medical damage in case of accident in the aquatic 
environment, it is important to have a good assessment of the changes occurring in the human 
body and especially those in the body of the person providing assistance in case of a water or 
sea accident. The purpose of the present study is to analyse the information gathered from a 
modern measuring device – waterproof measuring bracelet during examination of lifeguards 
during working hours in the summer active period. During the months of July to August 2020 
and July to August 2021 in Varna were conducted few researches of the changes in the heart 
rate of working lifeguards. The measurements were carried out during a full 24-hour cycle at 
the rescuers’ workplaces. The analysis of the results shows stability of the lifeguards’ heart 
rate throughout the working day due to the good physical preparation, mental resilience and 
calmness of the rescuers. 
Keywords: waterproof measuring bracelet, lifeguards, pulse

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