Hello and thank you very much for using HCM. I carefully read your question and I understand your concern.But you have nothing to worry. Ill try to explain you something.
As you already know we expect that the heart beat when you exercise might go up to 220 minus your age. So this high frequencies are quite normal when exercising. This is not a bad thing. This tells that your heart has a very good chronotropic activity.The chronotrop activity is the ability of the heart for changing its frequency according to bodies necessity. When a person begins to train all the body needs more energies, more blood and so the heart needs to beat faster to fulfill this necessity. When a person trains a lot, every day and for a very long time, gradually the body and the heart gets adapted with this activity and the heart begins to beats with lower frequencies during efforts. This is the reasons why it is quite known in cardiology that athletes or sportiest has low frequencies, because they have adapted hearts. But this comes slowly after training for long times, passing through a normal process when the heart beats fast at the beginning and gradually adapts.
So, you should not worry, your heart is strong and able to fulfill the body necessity and efforts. So it is ready for the military. Gradually you will see that you will not have this high frequencies when you will do the same exercises, ruining or swimming.
I hope i was helpful. Wish you good health and good luck to your new experience. Best regard from Dr. Ervina