Age limit for congressmen

Watching the hearings yesterday, it was painful to watch Grassley and Leahy go back and forth. They came off as slow and a bit feeble compared to the younger, more vibrant members. Grassley looked lost, and some guy (probably his aid) kept whispering in his air, seemingly telling him what to say. I have always liked Grassley...so it's painful to say. He is 85 years old and it shows. Leahy is 78 and is a little more with it, but still a shell of his former self. Anybody think there ought to be an age limit? The argument against, I suppose, would be that voters should recognize when their day is done, and shouldn't vote for them when they get to that point. But then again, voters continue to vote for Maxine and Pelosi....so....