42 bpm is not profusing your brain or major organs. Yes, it is normal for athletes to have lower pulse rates. Regardless of who you are 42 is too low. You can start CPR at 30bpm, anything below 60 is considered bradycardia
which is a cardiac issue to be taken up with your physician.
How are you counting it? Counting for 15 seconds and multiplying by 4? Counting for 30 seconds and multiplying by 2 or counting for a full min? These are the proper ways of doing it, if this is how you are comming up with your number than be evaluated in the ER tonight.