Proper running technique is critical for injury prevention, especially for the hamstrings. One of the key aspects to understand is that, “joint position determines muscle recruitment patterns.” For example, compare the difference if you were to perform a chin-up with your palms facing up (supinated), compared to a pull-up with your palms facing down (pronated). The muscle recruitment patterns throughout the arm and back are different with the change of the wrist/hand positions. Most people are stronger and can do more reps performing a pull-up, with the palms up in the supinated position.
The same holds true for sprinting. The ankle, knee and hip joints must be positioned at the proper angles, and at the right times throughout the stride cycle, to reduce the chance of injury and to optimize force production into the ground for speed. For example, if you extend out too far in front of your hip when you take a stride, you put added stress on the hamstrings. Also, if you push off too much during hip extension (drive phase) with the ankle, and point your toe down as you recover when cycling the leg forward for the next stride, this puts extra stress on the hamstring as well. So learning proper mechanics on how to run is crucial. Your muscles must work harmonically to reduce the chance of injury and optimize performance.
Another important element of keeping your higher level athletes safe of hamstring injuries is to have them stay relaxed when they sprint. For these higher level athletes the mental cue for this is to give 95%-99% intensity during all-out efforts. In other words, keep them one very small step below an all-out effort. The reason for this is when athletes think about giving that extra effort when sprinting, they tend to tighten up too much. This does not allow for a smooth harmonic reoccurring stride cycle sequence. All the muscles used for sprinting have opposing muscle groups that balance one another. These opposing muscles need to relax and contract within thousandths of a second.
For example, when the hip flexor muscle group fires to flex the hip forward to recover the leg, the opposing muscle group (hamstrings and glutes) should be less active to allow the hip to flex. Knowing how to fire and relax muscles quickly is a learned motor skill similar to hitting a golf ball or hitting a baseball. Optimal performance in these events are performed when the athlete is relaxed, not grinding their teeth with the feeling they are maxing out. This relaxed performance philosophy holds true for maximum sprinting speeds similar to many other sport skills.