In reply to IOAN D:
> just wandering how long would it take to lose climbing fitness if not climbing for an amount of time.
Not long to be noticable on boulder problems or stamina routes, especially indoors. However, the good news is that I've never found that layoffs in the order of months have actually adversely affected my trad lead grade.
I've had a couple of three to six month lay-offs and I've certainly lost some strength and stamina. However, properly developed engrams (muscle memory; i.e. technique) are not affected over that sort of timescale, if ever. When it comes to normal trad climbing (i.e. not pure bouldering) I've never noticed much of a difference when I've started up again. In fact, I often seem to much climb better as I tend to apply more technique and thought rather than just try to power through moves.
This goes back to the fact that technique counts for (nearly) everything in climbing. Unfortuantely the process of gaining that technique is rather slow and if you don't have it, a disproportional amount of 'fitness' seems to be required to compensate.
It's taken me 11 years to get to the stage of leading English 6a moves consistently. However, given my job and general level of fitness, I'm now sure that even if I took a year off I'd be back leading 5c straight away and climbing a few times a week I'd be back to my current trad standard in a month or so.
When it comes to sport climbing I think it's a bit different as you climb much nearer your physical (rather than pyschological) limit. I'd guess I drop about 1/2 a sport grade after 3 months off and possibly 1-2 after 6+ months. After a year off I might drop 2-3 sport grades but I think my base level of fitness and muscle memory would ensure that my climbing standard wouldn't deteriorate much further than that.
HTH