Complex sentence: He holds the national high school football record for career rushing yards, and on December 5,2015 he broke Herschel Walker's single season rushing yards record in the SEC in two more games but about 40 fewer carries than Walker.
Split into simpler sentences: He holds the national high school football record for career rushing yards. On December 5,2015 he broke Herschel Walker's single season college rushing yards record in the SEC in two more games but about 40 fewer carries than Walker.