It's definitely a faster game now, the game has evolved so much in past couple of decades.

More impact as in overall the players run faster, jump higher, have greater stamina. With better nutrition , sports science analysis and increases muscle mass the 22 players that start a game are far superior physical specimens to their predecessors. Plus sports men and women of all types are evolving and getting physically better not a surprise when you see world records being continually broken and times reducing in athletics.

Players run further, more sprints etc

Like I said email a strength and conditioning coach or sports scientist and you will get the answer you need. Or try and find a piece done by Gary Neville on the subject which explained it from a footballers view in laymen terms.