Isometrics on trainer to raise HR
 

I have been doing some isometrics with my arms(pushing/pulling on handlebars) while on the trainer and I watch my HR go up. Sometimes as much as +10 beats at a steady cadence. I first did iso's after shoulder surgery and thought it might be good to do while on trainer just for upper body/arm exercises. Didn't expect the HR to go up...just an observation:thumb:

I've noted my HR increasing as much as 50 bpm while doing planks (which continues to be an extremely difficult exercise for me) and have been wondering if this is normal.

Anyone here have as similar experience or know if this is a routine occurrence?