Was planning a ride today, but am definitely a bit sick. Just a slight cold at this stage, so I'll take another rest day in the hope that it doesn't get any worse. Resting heart rate is still at 41 - if it were elevated by at least 10 beats that would put my true resting pulse at 30, which is certainly not true. However, I definitely know I am too sick to be training, so I will not trust that test any more. Maybe it is only an "if" rule and not "if and only if".
This is my first cold for over a year, so I will not complain! (much)