You can listen to this article. Use the player below, download the MP3, or use iTunes. I’ve been lifting weights long enough that I’m confident knowing when I have another rep or two, or three, left in me (i.e., “reps in reserve” or “reps in the tank,” as it’s known) when performing a set of an exercise. But I can still be wrong. Like that time a few months ago when I got stapled by my …