The cozy fire in a fireplace is a common example of oxidation to produce heat. There is an oxidative system in the human body which also produces heat, though without any colorful flames. That oxidative system is put into action during warmup activity and other gentle movement of the muscles.
Today’s workout time consisted of rowing in the morning and SkiErg in the afternoon. You can see on the graphs that heart rate was a bit whacky/abnormal until 10 or 20 minutes was spent warming up for the sessions.
Any workout sessions for any day can be seen in detail via this: link to the online logbook. To see a session’s data and interactive graph click the “+” sign in “Action” column for that session.
Happy rowing to you!