So I went to do my 5th parkrun yesterday, full of hope for a good experience and perhaps a pb, but I found it a real struggle and jogged my slowest time yet (34 minutes) even having to stop and walk a few times. Trying to analyse this after, and I think there may have been two potential factors. I've had a cold for the past week - nothing too bad, certainly hasn't kept me in bed, but still a virus nonetheless. Also, I've been having a go at the Michael Moseley Blood Sugar Diet since Tuesday, which is basically a low carb/nil sugar diet. I suppose either of these, or perhaps both, could have affected my performance, but I'm still surprised by how much. I had assumed that it would only be a "highly-tuned" athlete that would notice a performance decrease in these circumstances. Thoughts?