Explosive muscle power lasts for only a few, fleeting seconds at the beginning of each set or sprint. As the clock ticks, your muscles´ reaction time and power output slowly fade. With the completion of each set, your ability to recover and move on to another grueling exercise is greatly diminished. By the end of your workout, your muscles are spent–you just can´t shake the nagging feeling that although you wanted to push out a few more reps, your muscles just couldn´t muster the strength. Sounds like you could use some creatine.