Leg pains at the start of a ride

So, for the past two seasons I have noticed at the start of my MTB rides that I have some annoying leg pains in my quads. I typically only notice this in MTB rides, but maybe that is because MTB terrain demands higher power output than a smooth surface road ride in order to get over things on the trail. I have not experienced this in the past and typically in the years before I could start my rides at higher effort levels without any pain. I have found that the pain does go away after about 45 minutes or if I just ignore it and push hard it will typically go away a bit faster and all is well for the rest of the ride.

My first thought is that for whatever reason my body has changed, and I now need a good warmup routine at the beginning of my rides. I am currently 52 years old, so this could just be the natural effects of aging.

I guess I would like to know if others have noticed this also. The thing that bothers me is that the pain is very noticeable and is something I have never felt on the bike in the past. The fact that it goes aways leads me to believe it is not an issue, but I do plan to bring this up with my doctor just to make sure.

Thanks for any feedback.

Just for the sake of a bump: it sounds like something is tight. Could be a tendon that you only use while on the mtn bike. Maybe due to a geometry or fit difference.

That makes sense. I can definitely check out my bike fit.