Heart

I am 16 and I am very active. In the last year or so, I have noticed something interesting about my heart rhythm, and was wondering whether or not I should be concerned. Whenever I start an activity, rather quickly (ex. start sprinting, stand up quickly, or just start jogging) my heart rate increases rapidly and my heart beats really fast. My chest starts to hurt and usually I have to stop because it is such an issue. Should I be concerned at all? Thank you!
-Mac

[Jerry_NJ]

Concerns you have should always be discussed with you parents.  

Many people who have a low HR and/or low blood pressure may have a brief lightheaded  period, then as the heart speeds up, that goes away.  Of course, if this is new and different than what you have experienced in the past it would seem something has changed.

It is alway a good idea to "warm up" before starting any highly stressed physical activity, such as sprinting.  Try that and see if it helps.

You didn't state what you HR is at rest or what you mean by "really fast".  A person your age can have a HR approaching 200 when working really hard and not have that be a problem.  I am not recommending you work that hard, run your heart that fast, I'm just giving some number range examples.  If you HR at rest is below 50, that could be something needing to be check, especially if it is new and is causing new troubling symptoms.

Good luck, and talk with your parents or guardians,