Do you need to have sore muscles after a workout to know you trained well? The idea that “the more sore you are, the better the training” is a common belief. But is it really true?
During a workout, tiny muscle tears occur in the muscles you’re training. The combination of these micro-tears and the breakdown of muscle proteins triggers an inflammatory response. This process produces substances like free radicals (which can damage cells and tissues) and histamine (released during inflammation or heavy exertion). The buildup of histamine causes swelling near the muscle fibers, which activates nerves. These nerves then send pain signals to the brain — resulting in sore, stiff muscles. This means your body is in recovery mode — a natural and beneficial process.
It’s probably familiar to you that you experience less soreness after the next workout. That’s thanks to your immune system, which starts responding more quickly to the training stimulus. This means it activates the recovery processes sooner.
But muscle soreness, or muscle damage that feels like soreness, is not necessary for building muscle. In fact, there’s an ongoing debate among scientists about whether muscle damage is required at all for gaining muscle mass and strength. Your body may simply become more efficient in responding to training — causing less soreness — yet important processes are still taking place.
Muscle soreness also doesn’t automatically mean your workout was effective. For example, running can cause soreness, but it contributes little to muscle growth. In fact, soreness that lasts several days could even hinder muscle development, because it might cause you to train less frequently.
So, muscle soreness is not necessary for muscle growth. Still, it has an important role: it acts as a signal to protect your muscles from being overloaded again before they’ve fully recovered. Your body wants to recover properly in order to handle the next session. Once it’s rested and recovered, you can push your muscles harder in the next training — and that’s how progress is made.