I live to move, so when I get sick its always hard to decide the best course of action. Do you fully rest, or does your body need movement? If you train will that set yourself back?
In the past I have trained while sick and noticed the sickeness seemed to stick around longer afterwards or even get worse again, I have had other sessions were the movement seemed to help my body burn out whatever remained of the illness, the problem was how to predict whether I was hurting or helping my cause by training through my sickness.
Being a dad has given me a new lense on this, my daughter does not stop playing because she is sick, but she does play differently. She takes longer breaks, asks for more cuddle time, plays quieter games and sustains intense activity for much shorter periods of time. The sickest she has gotten ended up being a day spent sitting in my lap but that was a total outlier the next day she was back to moving.
Watching this I realized that movement is great, we are not meant to be sedentary creatures except in the worst circumstances, however the ethic of training is not the best for recovery. Our bodies do not need another deep physiological inroad when they are already dealing with an infection, but they can benefit from the circulation, endorphin high, kinaesthetic feedback, and positive socialization involved in play.
Play is inherently autoregulating when its not fun you slow down or redirect, training is generally much less so if the program calls for some many lifts or jumps at such a weight or distance we try to execute that and that is when we can easily over stress our body.
So my personal answer to the question of what do when sick is to let go of your goals and your ego in your movement and trust your sense of play in guiding what your body needs.
I am recovering from a cold and followed this course on friday, I felt much better afterwards, I did not move with much speed, nor engage in high power or endurance efforts i just explored some interesting movement patterns and enjoyed the sun and the trees.
I hope you remember this inspiration the next time your body isn’t up for training but would benefit from some good movement play.