Is there a way of toughening up your thighs?

I did my long slow run this morning; 22 miles; and I felt pretty good till I hit mile 11 and then my thighs started hurting.  There's lots of hills around here and I think my legs were still tired from my mid-week running, but going downhill was a nighmare.

Every step going downhill really hurt my thighs and I tried all sorts of slightly different running forms to find what was best.

But I was wondering, is there a way of toughening up my thighs so I can chuck myself down these hills, rather than going down them gingerly 'cos they hurt badly?

Or is it a case of being patient and keep training?

if your mileage is good like cougie said ive always found squats helped me massively (used to do body pump classes)

if thats not to your liking then theres also leg raises or leg extensions 

I'm inclined to agree with cougie. You shouldn't be feeling any pain at 11 miles if your long run distance is 22, even if there are hills.

You maybe running up the hill too fast, you should try to maintain an easy effort, you should also not be wanting to 'chuck yourself' downhill either. Keep that for short sprints.

Personally I would not expect to feel pain on a long hilly run. if I was doing hill reps or hill undulations or similar speed work then I would expect to feel discomfort while I was pushing, that's why you have a period of rest between efforts.

If you want to xtrain then squats, lunges, jumping squats, jumping lunges, skipping core exercises all help. But will only help if your legs are rested and free from injury and you are not over training.

Thanks all; I don't think it was the distance (by itself) that wrecked my legs today, I've already done 2 x 20 mile runs and a 17 mile run prior to those, and quite a few 10 to 14 mile runs; but I did beast myself on Wednesday and I thought two days rest would be sufficient for todays 22 miles.  Obviously not.

I'll take on board your 'overtraining' points. 

My legs are sore, my left heel is cracked, and my groin hurts!  Poor me, eh? 

My first marathon, Cougie.  If it sounds like I'm doing too much for my first marathon, it may help if I explained that I'm an alcoholic (recovered), and we generally wring the life out of anything that we enjoy; that's my excuse anyway.

 The plan is to do a long run every-two-weeks till my last one three weeks prior to the marathon (Glos - 20 Jan) and then taper.  So I've another two to go.

I did start following a Hal Higdon training program, but it seemed a little bit too tame, but they say you can always tell a drunk, but you can't tell a drunk anything.

The legs, groin, and heel are feeling a bit better today; and I'm having a rest day (ish; just an easy half hour on the exercise bike).