I'm a junior in highschool and I really need help with speed, more specifically using it during races. I'm mostly a 3200 guy , I do around 60 miles a week. When I do 100m strides barefoot our football field after I run I usually run around 14-15 seconds. The fastest one i've ever done was 13.6. I never really can shift gears in a race. I had really weak hips, hamstrings and glutes that caused me to get injured, up until around last month I couldn't even do 1 bodysquat. I'm a little stronger now but I still feel tight in my hamstrings alot and I don't have alot of backkick. My coach noticed that when I do strides I stay pretty level and hardly bounce at all.
Anyways, is there anything that I should do so I can start getting better speed/using it in a race? And does flexibility have anything to do with it? I'm our teams #1 guy for the 3200 and I'd really like to run well this year.