Title Comparison of the loading rate during swimming with the load of various upthrust. Objective Comparison of physical intensity during swimming with the load of high upthrust and low upthrust. Methods The Method used in this work was quantitativ research in the pool with counterflow (Flum, FTVS UK). There were 7 people tested. The loading rate was observed by heart rate monitor with chest strap. It is randomized study with crossed design and the method of data eleboration was comparative analysis. Results The results compare physical intensity during swimming with high upthrust load and very low upthrust load. It shows the differences in intensity between swimming with various types of load. It was found, that swimming with the load of high upthrust causes lower physical intensity than swimming with the load of very low upthrust. Swimming with the load by pulling is just a bit preferable than pushing. The heart rate by pulling is lower about 2 - 7 bpm than pushing. Keywords Military swimming, upthrust of the load, heart rate, swimming with load.