Heart Rate and a few more points.
Tony's correct.
I'll add a few things I've learned over the decades.
50 is quite typical for someone's who's very fit.
The under exercised American has a heart rate on the average of 80 plus.
So the more fit a person becomes, the lower their HR should become. 50 to 45 seems to be the lowest limit for most.
Heart rates can tell you a few other things as well.
If your HR is still above your average 24 hours after exercising, it means your body hasn't recovered yet from the exercise.
If you eat and your HR jumps 6 beats and higher, you may be allergic to one of the food items.
A slightly lower than daily average HR may mean you need to eat.
So always eat prior to donating blood. As they may force you to eat cookies and OJ before donating (been there done that.....;-)
If your heart rate is 8 beats and higher first thing in the morning (assuming you didn't over exercise) you may be coming down with something. So lay off the exercise for the day and drink extra liquids, go to bed early.
Healthy people may encounter low level infections because of their health. The body can easily "handle" it, but doesn't git rid of it.
They may actually need to exercise intensely, which suppresses the immune system for 4 hours.
This allows the low level infection to blossom to a level the body sees as unacceptable.
And the last, be careful getting up from sitting, you've acclimated your body to high volumes of blood flow, you may become prone to getting slightly dizzy coming from a sitting position.
This is common for very fit people.
To Your Great Health,
Gracefully Savage