For a lot of bodybuilders, competitive athletes, and guys who just like to work out, sore muscles are the marker for a “good” workout.

If you’re muscles aren’t sore the next day or the day after that, then you probably didn’t work out hard enough—that’s what a lot of us have been taught to believe anyway.

But is that really true? Is it necessary for us to train hard enough so that every time we work out, our muscles are sore? Let’s find out.

Debunking the Lactic Acid Myth

For years, fitness and medical experts thought that sore muscles were the result of lactic acid building up after intense training sessions.

Lactic acid is produced when you exercise or lift really intensely—when the muscles are screaming for more oxygen than the blood can possibly deliver at that moment.

Because the body can’t deliver the oxygen the muscles want, it compensates by beginning another process—one that works in the absence of oxygen.

Lactic acid is a by-product of this process. And since it is an acid, it causes us to “feel the burn.”

So while, on the surface, it seems to make sense that lactic acid could be the culprit in causing sore muscles after an intense training session, it’s just not so.

In reality, the lactic acid gets washed away from the muscles pretty quickly; it doesn’t hang around for hours or days.

But the muscle soreness we’re talking about here doesn’t show up for anywhere from as little as 8 to up to 36 hours after we train. So if it can’t be lactic acid causing the soreness, what is it?

Modern science points to micro-traumas as the real perpetrators that cause post-training muscle soreness. Micro-traumas are just what they sound like: small abrasions, tears, or otherwise localized damage to muscle fibers—specifically, the membranes and contractile elements.

Researchers have taken biopsies of muscles suffering from training-induced micro-traumas and discovered that the z-bands were bleeding, causing their function to be disrupted.

The z-bands are filaments that hold the muscle fibers together as they slide over one another while contracting. When they’re damaged and bleeding—even though it’s microscopic—the muscle fibers become swollen and, of course, sore.

They’ve even found a way to evaluate just how badly the muscles have been damaged by measuring the level of creatine phosphokinase (CPK) in the bloodstream. CPK is normally found inside the muscle fibers but when the fibers are damaged, CPK is released into the bloodstream.

The higher the level of CPK in the bloodstream, the greater the damage to the muscles, which means more soreness.

Some people say that stretching after you train can alleviate the severity of delayed onset muscle soreness (DOMS), which is what it’s being called these days. However, knowing what we now know about what causes the soreness, we realize that this just isn’t true.

While stretching—before and after a workout—is always a good idea, it won’t do much to reduce or eliminate sore muscles the following day because micro-traumas are the real source of the pain, not lactic acid.

So is muscle soreness necessary? The answer is that, to some degree, yes, it is needed.

It’s the stress or trauma that comes from lifting hard and heavy that causes our muscles to grow and become stronger. If you never train to the point where your muscles are sore the next day, then the truth is, you’re not training hard enough, and you’re not seeing the results you’d probably like to see.

On the other hand, ignoring the soreness and forging blindly ahead, training “through the pain,” is not the answer either. If you don’t pay attention to what your body is saying, you’ll pay the price sooner or later and wind up injuring yourself—possibly very seriously.

Secrets to Managing Soreness

1) Increase your workload gradually. Don’t try and show off by making huge leaps in the amount of weight you’re lifting; give your muscles time to adapt.

2) Allow your body plenty of time to rest and recover between training sessions. Remember, the rest and recovery part of bodybuilding is equally as important as the lifting weights part. It’s during this process that you’re muscles are actually growing—not when you’re working out.

So while it shouldn’t really be your goal to completely eliminate training-induced muscle soreness, it is important to know that you can manage it and minimize its impact on your body and your training routine.

For me personally, whenever I bench press heavily, my muscles always get sore and I kind of like it that way.