There’s a fine line between exercise and torturing yourself.
Recently, I helped a friend of mine move into a new apartment. It was an all-day affair, with lots of lifting, lugging, dragging, and loading. Strangely, though, while I was certainly tired out during the moving process, I didn’t feel especially sore. Turns out all I needed was to wait a little while; once we were done for the day and I plopped down in my computer chair to relax, it suddenly felt as though my limbs were made of cardboard. Really cheap cardboard. I was sore as heck, and continued to be into the next day. I asked myself “should I work out today?” Then I attempted to take a few steps out of bed and my shins felt like they had been kicked repeatedly. It was then I decided “no, I don’t think I should work out today.”
Sometimes, working out when you’re sore isn’t a big deal. If you’re having aches in one part of your body, move to a different part. If, however, you’re completely sore all over, then it’s probably a better idea to just take a couple of days off. Muscle soreness is a result of numerous micro-tears in your muscle fibers. That’s totally normal; it’s how you build muscle mass. But those tears need time to heal properly. If you just keep tearing them over and over before they can heal, you’re just going to hurt yourself.
What you need to consider when deciding whether to work out while sore is exactly how sore you are. If you can still get up, walk around, and lift your limbs properly, then you should be okay for some light work. But if you’re too sore to get out of bed, then you need to rest. A little muscle stiffness in the morning is normal, but it’s supposed to go away with your morning stretch. If it’s still there, it’s probably going to be there all day, so you might as well take it easy.