The Nordic curl

Hamstring injuries are a common occurrence in high intensity running, and the risk appears to rise with age.  Any muscle can be injured with overuse (too much volume/ insufficient rest) and overload (too much intensity or incorrectly used) but age creates an additional issue, which is tightness.  A tight muscle that is also weak is much more likely to be injured than one that is simply weak or overused.  My strong advice to anyone with tight and weak hamstrings is to regularly 'stretch-stress' the muscle to improve working length.  Exercises that stretch-stress the hamstrings include inchworms, reverse inchworms, and aeroplanes (single leg Romanian deadlifts).  The good news is that stretch-stress doe not require external load - body weight is sufficient.  Stretch-stress exercises are ideal warm-up exercises for gym and sport.
Sprinting is a special case for hamstring injuries because the muscles are loaded through a large range of motion, and a high volume of high intensity work is performed.  Even a comparatively short, 50m, sprint involves ~20 repetitions per leg.  That's a lot of work under maximal power conditions!
Fortunately, the risks can be easily improved and there is one exercise, in particular, that displays excellent efficacy for reducing hamstring injuries: the Nordic curl.  Clips are available below for inchworms and single leg inchworms, which we use with other variations to stretch and strengthen the hamstrings, as well as the Nordic curl.

inchworm

reverse inchworm

nordic curl - no partner needed

nordic curl - partner assisted