My son said today his pulse when resting is between 110 -120 bpm.  It used to be around 60.  He is 19 and pretty fit, slim, doesn't smoke or drink.  I'm worried about cardiomyopathy or something awful like that.  Can you please advise, RLR?  I don't want to get him worried about his heart, I know what that is like - but it doesn't sound right to me.   He is doing a triathlon in 4 weeks, is it dangerous?  I felt his pulse and it really was very fast - he used a pulse counter a few times during the evening, and it came up at 110 each time. Earlier today it was 78.  I really don't want to make him constantly aware of his heart, I've suffered enough with that - but if something is wrong, we need to get it sorted.  Any advice, please?

Thank you, I hope you are right.  I'm not sure how long this has been going on for, I don't want to over question him and get him concerned.  He is seeing a doctor on Thursday about something else and said he will ask about it.  He has only just decided to take part in this race, so hasn't been doing training until the other day.  He does take  a good amount of fluids - way more than I do.  I'm just trying to get my own palpitations under control, and I know it probably looks like I'm transferring worry to something else - But  my son mentioned this without any sort of prompting and he doesn't know about the palpitations I have problems with.

Okay, the readings provided would suggest mild sinus tachycardia and it's important to realize that this is benign in nature and not of the order of magnitude that places him at risk, particularly at such a young age. There are many factors which may be increasing sympathetic tone to generate this sort of phenomenon and the fact that resting pulses of 78 are interspersed would be further evidence that nothing serious is wrong here.

It's important to realize that factors as simple as dehydration can produce sinus tachycardia in this range, or even exposure to high humidity wherein the body has difficulty cooling the skin through sweat evaporation.

Regardless of state of health, all athletes must become aware of their maximum heart rate performance based upon a formula and target the proper percentage of that maximum during any athletic event and in any climate conditions of high humidity, extra care must be taken to stay well-hydrated and conscious of one's heart rate as it relates to the maximum target.

It's also important to realize that focused attention to one's heart rate, coupled by concerns that something serious might be wrong, will in of itself produce elevated rates as a consequence of apprehension and up-regulation of the sympathetic nervous system.

Best regards,

Rutheford Rane, MD (ret.)