Many programs have been pitching this idea for years, some take it to the extreme and tell you that a single rep should last 20 seconds, (10 up, 10 down). One

Many programs have been pitching this idea for years, some take it to the extreme and tell you that a single rep should last 20 seconds, (10 up, 10 down). One thing to keep in mind is that you have 2 types of muscle, twitch and power. Sprinters overdevelop their power muscles, long distance runners overdevelop their twitch muscles. Your best bet is to try to find workout strategies to find a good balance between those two.