Back in the day, every bodybuilding expert and would be "Mr..." something recommended working the hamstrings for all the wrong reasons. Because in my humble opinion, too many of those experts looked at the hamstrings as being analogous to the biceps of the upper arm. And who could blame them, or the neophytes among us?
The hamstrings are medically identified as biceps femoris. The front portion of the upper arm is called biceps. Ah ha - the same name must mean they are the same, hence, let's all train them the same.
But it's not the same. Let's be clear that I am not a medical doctor nor am I a licensed fitness guru nor to do I play either of them on TV. Still, I think the main function of the hamstrings is to keep us upright. It is to assist the hips, glutes, and lower back in picking things up. It is to keep our upper body stable as we walk, run, or move forward.
Weak and/or tight hams open us up to lower back injury.
It fights gravity.
As we get older, too many of us tend to stoop. It's as though the weight of the ages are on our shoulders. The young are tall and straight. The sphinx's riddle tells of "walking on all four's in the morning, on two's in afternoon, and on three's in the evening." The elder walk on three's because of the cane.
Yet it need not be so.
And a key to this is having strong, flexible hamstrings.
A great exercise that strengthen and stretches your hamstrings, along with working the glutes, hips, and lower back, is the stiff-legged deadlift. This is not the straight leg variety that locks your legs ramrod straight. A stiff-legged deadlift keeps a bend in your knees that puts your lower back in a stronger position.
This exercise can be done with barbells, dumbbells, or resistance bands. Regardless of what you use, you must remember to keep you back straight and your knees slightly bent throughout the whole movement. Unlike powerlifters, you also do not want to excessively lean back at the top of the movement.
And your hands should not descend more than a few inches past your knees on the downward, end movement. If you keep your back straight and shoulders square, you will not be able to go lower, regardless. The end movement is not to touch your toes but to get a great stretch in your hamstrings and glutes. Keeping your shoulders square and back straight is critical to this.
As for how and when to do them, I would suggest about twice a week along with an overall quad movement like the lunge.
Although I am a big fan of squats, I think as we get older; it may not be the most productive exercise out there. If it works for you, then by all means; you should continue to do them.
But at this point, I think pairing stiff-legged deadlifts with dumbbell lunges make more sense. And, I recommend twice a week. Your objective should be 3 to 4 sets with the repetition range between 12 to 15 reps.
I have always recommended doing squats, lunges, and deadlifts as being the best combination of exercises for legs. For those of us over 50, I think dropping the squats makes some sense. Lunges and deadlifts will get the job done while keeping us out of the injury zone.