How much will my 5k time fall because of injury or illness

Muscle cells
Muscle cells (Photo credit: TheJCB)

Let’s say you are a 20:00 minute 5k runner so, depending on how old you are, you are at least half decent and generally ‘in a good place’. The dread of an illness or injury knocking chunks from your hard fought5k time is evident to many.

2:22 marathoner, Jeff Gaudette, gives these estimates:

Days of not runningReduction in fitnessWhat this means for a 20 minute 5k runner
1-7 daysNegligible reduction in VO2 max and muscle powerNow running 20:10
10-14 days6% reduction in VO2 max and minimal reductions in muscle powerNow in 21:05 shape
14-30 daysEstimated 12% reduction in VO2 max and decrease in muscle powerNow in 23:00 shape
30-63 days19% reduction in VO2 max and significant decrease in muscle powerNow in 24:00 shape
63 days or more25.7% reduction in V02 max and significant decrease in muscle powerNow in 25:30 shape

So, he’s done some research into the science and then extrapolated from that. So it’s not his fault but I would suggest the falls he suggests are greater than what would happen reality.

I just can’t see how anyone who can do 20:00 would fall to 23:00 after 2-4 weeks. I just don’t see that.

And after 2 months of inactivity falling to 25:30 I just can’t see it. That’s a quantum change.

Still, for those of you worrying about Christmas over indulgence then you’ve probably only lost 10 seconds. I’ll buy that.

Certainly cross training (eg swimming, cycling) or mild aerobic activity (if possible) WILL halt the decline. I’ve found that myself.

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