Don't train when you're sick.

When it comes to recovering from ANYTHING - sleep will be your best tool.

If you're sick taking a nap in your usual training time will do you more good than a compromised training session with your CNS in the pits even if it's at reduced intensity.

Training while sick is silly because you're not recovering from your usual activity and now you want to overload that recovery capacity even further?

It's not beneficial and will only prolong the infection.