Then why doesnt this maturation lead to increaese in speed in all the other sprinters in high school? I mean why is there only one exception? In ontario, canada, there are a huge number of sprinters, and this dude was a exception, there must be something more to it than physical maturation.
This maturation leads to increases in speed all the time. I was the same way in hs from my jr to sr year i went 12.3 – 11.4, didnt grow very much but the body was still maturing. Another time I took a semester off of school when i was 19 and did a meet after not training at all and got a high jump PR of over three inches. I would say most high school sprinters increase in performance is due to maturation because in my experience there are not a ton of great hs track coaches and even less in the strength department.