getting stronger

Had a decent run last night. When I woke up yesterday morning though, I didn't think I'd be doing any workouts. Since last Friday, I've been fighting off the crud. Haven't come down with anything full on yet, but it's been trying to overtake me. Yesterday morning, I felt the worst I have so far with fever and coughing with junk in my sinuses and chest. Did a hot shower and some Zycam with EmergenC and hot Green Ginger Tea and felt somewhat better. Time has not been on my side with training so after work, I decided to head out to the park to get in a short ride before the run. I didn't have to knock over any newbies on the trail this week and I was able to get in a good short loop in which helped loosen up the legs a little. Some of the sounds my bike is making tells me it needs a LOT of maintenance. Got back in time to stow the bike and meet the trail nerds for our Tuesday night ritual. 8 others showed up (including 2 newbies) and Bad Ben lead the pace as usual. The first loop went smoothly with a slightly faster than normal first loop pace. Finished that one in 42 mins. One new guy headed back to his car and the rest of us soon continued on the second one. Some of us were still talking at the trailhead when Bad Ben quietly took off on the second loop. Caleb jumped on his heels and I followed in line and the rest got the hint quickly. We smoked through the first three quarters of a rocky mile before settling into a more regular fast pace. The last 2 miles, I felt my energy draining fast and I knew it was the germs in my body gobbling up all my reserves. I was able to hold on and finish strong for that 34 minute lap. Within 120 seconds of finishing, as my breathing subsided and my heartrate returned to normal, I started feeling terrible. The coughing (which was absent during the run) returned as did an immediate headache and I started shivering uncontrollably. Couldn't get warm even though I drove home with the heat cranked up all the way and it was only 43 degrees outside. Once home, I sat in the shower until the water heater had given me all it had. Then downed some Nyquil and went to sleep a little earlier than normal. Today I feel a little better, but am still hitting the Zycam and EmergenC in the hopes of mitigating this crap before it gets worse.
In summary, I'm not sure if running while sick is good for the muscles or not. I felt great during most of the run and I know my legs needed the workout. Can you really make progress in training if your body is fighting off sickness?