I have a 2018 that's been working really hard with strength and speed the past few months. In particular the 60 for the past six weeks. Our speed guy started with an assessment to find areas of tightness or if there was anything out of alignment.
Result: backside of hips were really raised and out of alignment causing a lot of glute/hamstring tightness. Hip flexors and IT bands were also really tight making the glute/hamstrings even more tight. He couldn't drive his legs, he couldn't activate the primary driver - the glutes. Absolute zero knee drive. Also, he wasn't breathing, totally taught in upper body with the grimace in the face. Ugly looking runner for an extremely athletic kid. I was perplexed. He had been bummed going from a reputation as a quick kid to now one with avg speed.
My son was shown a lot of stretches to be done on Styrofoam roller, he was shown a way to use a lacrosse ball to grind into the hip flexor and IT bands twice daily. After two weeks his glutes and hamstrings were more flexible.
Running wise: improving technique at start, but the emphasis was to get a forward lean over his hips in the direction of his run and stay low as long as he could without popping up out of his running posture. He was popping up too quick at the 5 yd mark, losing momentum. HIs 10yd split was 1.7. He's now after 6 weeks staying low thru almost 15 yds then getting more vertical. His 10yd split now 1.48. We haven't tested 60yd in last two weeks, but the 10,20, and 30yd splits have been dropping nicely.
Not trying to be the expert here. Ex athlete, very interested in mechanical processes, but more focused on finding a coach that can engage my son and find progress to help him. Out of breath with my run on sentences. Oh, he is now breathing and relaxed when he runs.
His goal of 6.7 in next few months is reachable.
Just a story..