I have always wanted to look at the physical effects that a cold can have on performance. We see over 100 athletes every day in our facility, and during the winter months it seems like half of them are either getting a cold, have a cold or just getting over a cold. We try to make adjustments in the training for these players, but I have always wondered exactly how much they are affected by a cold.
Last week I came down with a cold. So as I felt I was reaching the peak of my symptoms, I put on a heart rate monitor and ran our 4 mile interval test on the treadmill. I was not trying to break any records, but I was giving it just about everything I had at the time. My heart rate was very high and I finished in just under 39 minutes. My speeds in the sprint intervals were between 13.5 and 14.8 mph. Five days later I felt as if I was almost over my cold and I decided to run it again and compare the two graphs. This time, my heart rate was much lower and I finished in 34 minutes. My speeds in the sprint intervals were between 15.6 and 16.4 mph.
Here are the two graphs (top graph is with a cold).
What was most interesting to me is how I felt during the sprints. With a cold, my heart rate would not come down and seemed to jump up fast, even though I was not running very hard. Without a cold, my heart rate never got very high, I sprinted 2 mph faster and seemed to be much more focused. So focused in fact that I held my sprint speed on the last sprint all the way to the 4 mile mark (thus the HR spike at the end of the workout).
I think we as coaches need to be more sensitive to the effects that illness can have on the cardiovascular system. If players are sick and still trying to play at a high level, their HR may be higher than normal which would cause not only fatigue, but also a lack of focus. High HR, fatigue and lack of focus can create the perfect storm of injury risk factors. I know this was not a publishable research study (and it was not intended to be), but it does give us some insight into how the common cold can affect performance.