I'm 41, and I find I need more warm-up than I used to. Although, truthfully, I always have needed a good warm-up. I am NOT a sprinter. Not in any way, shape or form. I seem to take awhile to get really going, but then, when I do, I might not go fast, but I can go long.

I find that if I don't get a really good warm-up, and I try a hard effort too soon, I never really do hit my stride for a ride nearly as well as when I warm up more slowly.

That said, I am finding that now, in July, my HR does not go nearly as high (nor do I gasp for air in the same way), as it did in February on the same early hills in any given ride.

I don't have asthma. For me, I think it is a combination of fitness level and age.