Hamstrings - the V12 engine

 If I had to pick only one muscle group which I believe is the most beneficial for athletes (strength athletes, track athletes, fighters, players, etc.) I would not pick "core" as many people would; I'd pick hamstrings.

Hamstrings are absolutely essential for power production when sprinting, running, jumping, skating, football, rugby, basketball, and pretty much any other sport. 

Hamstrings have two functions: they assist in hip extension and in knee flexion. Strong hamstrings ensure knee stability because they are attached below the knee. They can become insanely strong, powerful and muscular with proper training.

I recommend people train hamstrings twice a week, heavy with low or moderate reps.

Here are my TOP 5 Go To exercises for strong and powerful hams:

1/ Sprinting

Yes. Sprinting. There is no other movement for powerful contraction of hamstrings. They can produce fantastic results. If you look at elite sprinters - they all have muscular and powerful hamstrings. I like to do 8-10 sets of 130-150m uphill after some light running warm-up.

2/ Glute-Ham Raises

Lower yourself slowly with anchored ankles and then with a slight push with your hands reverse into concentric motion. You can do them with staight hips, bent hips, trunk rotation.

3/ Single-Leg Hip Raise

With one heel firmly against the bench fire the hamstring and push your body upwards using hamstring and glutes strength. It looks easy but it is not. I feel this exercise in the glute/ham tie-in. Go for higher reps.

4/ Power Kettlebell Swings

With only slight bend in the knees, let the KB swing far between the legs they contract the hamstrings powerfully to swing the kettlebell forcefully forward. Don't use your hands, they only hold the weight. The power comes from hamstring contraction. I like doing these for time of for many sets of 20-30 reps.

5/ Deficit Stiff-Leg Deadlift

People often confuse Romanian deadlift and Stiff-leg deadlift. RDLs are a glute exercise and SLDLs are a hamstring exercise. Sure, they overlap but the focus is clear. You can stand on a small block to increase the range of motion and thus the stress on hamstrings.

Good luck