Hey fellow was reading this book about weight training by Bill Pearl. Great book about how to exercise right by the way. According Pearl if you can't do a minimum of 12 reps on weight load you have on bar, that weight load is to heavy for you, so you need to reduce to a capacity where you could get comfortable to do at least or more 12 reps (Pearl 2001, page 24). So next time don't overkill yourself at the gym trying to lift more than you can't handle. Test yourself with the 12 reps requirement.