Sudden acute leg stiffness - why?

[Lycra Man]

On Sunday I went out for my usual Sunday ride, deciding to follow a longish 45 mile route I have done in the past, from Waddesdon to Thame to Postcombe, up to Stokenchurch, on to West Wycombe and then back home via Princes Risborough and Aylesbury. Mostly rolling with one big up following by a pleasant down in the middle.
I didn't try particularly hard, but when I got home, my upper leg/groin muscles were very stiff, and I have been walking down stairs with reducing stiffness/discomfort since.
Prior to the Sunday ride, I have commuted normally on 3-4 days a week, doing 30 miles in a round trip, from Waddesdon to Leighton Buzzard, so I am not out of practice.
I thoguht I was fit enough for such a ride at 'normal' intensity for me.
What would cause such stiffness, and can it be avoided by managing intensity of effort?
Lycra Man

[vorsprung]

There are a lot of viruses and that kind of thing about at the moment.  If your body is fighting one off you might feel ok but be short on one of the substances that the body needs to prevent muscles reacting poorly

Also although the weather is great at the moment we are moving into autumn/winter.  Just as there is a "spring effect" when we get a bit faster for no reason so also there is a slowing up factor this time of year. Maybe that has something to do with it?

[Lycra Man]

I did my commute ride Wednesday night/Thursday morning, and Thursday night/Friday morning (I leave my car at work) and that went OK. Gradual easing of the stiffness through the week.

My weekend ride was Saturday, and although I did consciously take it steady, I did not experience any similar after effects, so I have put this down to a random reaction to me probably trying harder than usual.

That'll teach me!

Lycra Man

[mrcharly-YHT]

I had problems last week. Rode 2 days, then my legs felt like they'd been beaten by rubber hoses.

I thought I was just being a wimp, then the kids got very ill over the weekend and the glands in my neck blew up.

Lots of Virii about.