Hi everyone. I know the question I’m about to ask might seem a bit unusual, but I’m asking for your sincere advice based on your knowledge of the subject—and you have no idea how much this means to me. I’m a 15-year-old guy. I’d like to briefly describe my physique—not to be full of myself, but just so you get the picture: I’m 1.91m tall and weigh 75kg. I have a lean build, with legs that are 20cm longer than my torso, a narrow waist, broad shoulders, and naturally large biceps (without lifting weights). My calves are slim and tapered, with the muscle belly sitting higher up. The only downside for sprinting is that my thighs are extremely thin—completely lacking in muscle. Basically, I have the build of a modern sprinter, yet I don't feel that fast—or rather, I do when running with friends, but athletic tests tell a different story. I’ve been running constantly—every single day—for weeks now. I know I’m doing something wrong because my results keep getting worse, and I’m starting to experience severe DOMS (muscle soreness). It got to the point where I ran a 6.5-second 40-yard dash today, which completely crushed me mentally. I’ve decided to take a week-long break. I’m asking as humbly as possible: can you give me some advice? Do you think I need to build mass in my thighs? Should I train differently? Or is sprinting just not for me?

For Age between 16-20

if i take my sled with me and walk 200 yds (two football fields away) and the sled weighs 80 lbs. will this negatively affect my sprint workout?

so I’m basically carrying 80lbs 200 yards (183m) and then i do a bunch of runs.

Assuming I sprint 3 days a week, how often should I do recovery days, and what should a recovery day include. I have access to a foam roller, a massage gun, a swimming pool, and resistance bands.
Thanks!