How quickly does cardiovascular fitness dissipate?

[Blarg]

This is just my experience from playing soccer, running, and from martial arts, which I used to do as a teenager and young adult, at various stages of my life, pretty full-out, daily or near there for years. My friends all noticed the same thing and agreed; we could tell a marked difference in how winded we would get if we hadn't done any hard running or heavily aerobic work-outs for 2 to 3 days. Your mileage my vary, but this was pretty consistent with us when we were at the peak of our abilities. I think if we were at less than our peak, it probably wouldn't have been so easy to notice how quickly we could drop down from our usual performance. But the standard you set when you're at your best is very unforgiving.

I'm not saying we were suddenly in bad shape, or anything, by far. But there was no getting around our disappointment at how quickly we could come off our peak.