** Updated heart rate data **
I recorded my heart rate data last weekend while racing at AutoClub Speedway. Looks like my racing heart rate is quite a bit higher than my practicing heart rate - 116bpm racing vs 85bpm practice or 36% increase!
You can see at one point during the race (annotated) my heart rate goes to 125 whereas it never got close to that in practice.
Overall, racing is about equal to fast hiking or jogging - in terms of physical exertion.
Mental exertion level is "extremely intense" to say the least.
