The No Pain No Gain Myth: Soreness Was Never the Receipt

A study actually tested the slogan. Half the group got sore. Half didn’t. Both groups gained exactly the same amount of muscle.

There’s a specific walk reserved for the day after leg day — a stiff-legged, slightly undignified shuffle down stairs that gym culture has turned into a badge of honor, complete with its own acronym and a small library of gym-poster slogans printed over stock photos of grimacing athletes. Can’t sit down without wincing? That’s proof it worked. Woke up unable to lift your arms above your shoulders? Beast mode, allegedly. The soreness itself has become the receipt, the thing you show as evidence that the workout counted.

Here is the myth: that pain and soreness are the mechanism of progress, that more discomfort means more gains, and that a workout without noticeable soreness the next day didn’t really work.

Here is the bust: researchers built an experiment specifically to test whether muscle damage and soreness are actually necessary for muscle growth and strength gains. They aren’t. Two groups did the identical total amount of training. One group got dramatically sorer than the other. Their results were, for practical purposes, indistinguishable.

The Study That Tested the Slogan Directly

In 2011, researchers at Northern Arizona University and the University of Utah published a study in the Journal of Experimental Biology with a title that got straight to the point: “Muscle damage and muscle remodeling: no pain, no gain?” They split participants into two groups. One group spent three weeks gradually ramping up into the training program, specifically to avoid triggering noticeable muscle damage. The other group jumped straight into a demanding bout of exercise with no ramp-up, the way most people actually start a new fitness kick.

Both groups then completed the same eight-week eccentric-cycling program, matched so the total amount of work performed was equal. The results were exactly what you’d predict for the soreness itself: the group that skipped the ramp-up showed more than five times higher levels of creatine kinase, a blood marker of muscle damage, along with much higher self-reported soreness and exertion. The ramp-up group showed almost none of that.

But the outcome that actually mattered — muscle size and strength — didn’t budge between the groups. Cross-sectional muscle area increased by the same significant amount in both. The growth-signaling factor IGF-1Ea rose by similar amounts in both. Strength improved by 25% in the low-damage group and 26% in the high-damage group, a difference well within normal noise. The soreness had no measurable relationship to how much the muscles actually grew or strengthened.

What Soreness (DOMS) Actually Is

The soreness that shows up a day or two after a hard workout has a name — delayed onset muscle soreness, or DOMS — and a fairly well-understood cause. It isn’t lactic acid, despite that explanation’s persistence in gym folklore since at least the mid-20th century; lactic acid clears from the bloodstream within about an hour of exercise, long before soreness even begins. DOMS instead comes from a combination of small-scale damage to muscle and connective tissue, plus the inflammatory response that follows as the body repairs it, along with temporary swelling and stiffness in the affected area. It shows up most after eccentric-heavy movement — the lengthening phase of a muscle contraction, like the downward part of a squat or the landing phase of a jump — especially when that movement is unfamiliar to the body performing it. Soreness typically builds over the first 24 hours, peaks somewhere between 24 and 72 hours, and fully resolves within about a week, regardless of how effective the underlying training actually was.

Why You Get Less Sore While Still Improving

Here’s the detail that should have killed the slogan decades ago: soreness reliably decreases the more familiar your body becomes with a given exercise, even as your training continues to work. It’s called the repeated bout effect — your body mounts a smaller damage and inflammatory response to a movement it has already adapted to, compared with the first time it encountered that stimulus. A lifter who was crippled with soreness after their first squat session will typically feel barely anything after their tenth, despite lifting more weight by then, not less. The effect is specific enough that changing exercises, adding new range of motion, or simply returning to training after months away can bring the soreness right back, even in someone who is otherwise well-trained — which is itself further evidence that soreness tracks novelty, not effort or effectiveness.

If soreness were actually the mechanism driving progress, that pattern would predict stalling gains as soreness fades. It doesn’t happen. Experienced lifters keep adding weight to the bar for years after their bodies stopped registering much soreness at all, because the thing driving their progress was never the ache — it was the gradually increasing demand placed on the muscle, something trainers call progressive overload.

The Pain That Actually Means Stop

None of this means all discomfort during exercise is fine to ignore. It means there are two different signals wearing the same word, and mixing them up is how people get hurt. Ordinary DOMS is diffuse, affects a muscle belly rather than a single point, feels roughly symmetric if you trained both sides, and tends to ease up once you start moving and warm the area. Injury pain behaves differently: it’s often sharp, localized to a specific spot rather than spread across a muscle, sometimes centers on a joint or tendon rather than muscle tissue, and tends to get worse rather than better as you keep moving. Runners who push through a sharp, localized ache in the shin or heel, for instance, are the population most commonly diagnosed with stress fractures and tendinopathy — overuse injuries that show up specifically in people who treated a warning signal as a discipline test. That second kind of pain is the body’s warning system working correctly, not a test of willpower to override.

Why the Slogan Stuck

None of this is really about muscles. “No pain, no gain” survives because visible suffering photographs better than the actual mechanism behind it. Progressive overload is a spreadsheet — a slowly rising line of weights and reps tracked over months. A grimace mid-set, or a stiff-legged walk down the office stairs the next day, is a story you can tell in one frame. Gym culture rewards the frame, not the spreadsheet.

It’s the same shape every myth on this site keeps finding: the visible, dramatic version of an idea out-competes the boring, accurate one, because the boring version doesn’t fit in a caption. Nobody’s gym selfie caption reads “increased my working weight by two and a half percent this week,” even though that sentence describes the entire mechanism of getting stronger far more precisely than “I can’t feel my legs” ever did.

What To Actually Do With This

None of this means training should feel effortless, or that a demanding workout is something to avoid. It means soreness is a side effect of novelty and eccentric load, not a receipt for effectiveness, and it stops being a useful measure the moment your body adapts to what you’re doing — which, if your training is working, happens fairly quickly.

• Stop using next-day soreness as your workout scorecard — the Flann study found identical gains with and without it.
• Track progressive overload instead: weight, reps, or volume trending upward over weeks, not how you feel the next morning.
• Expect soreness to fade as you adapt to a routine — that’s the repeated bout effect working, not regression.
• Learn to tell diffuse, symmetric muscle fatigue (normal) apart from sharp, localized, or joint pain (a stop signal).
• Ramp up new exercises gradually rather than starting with a maximal, damaging first session.
• If pain gets worse during the activity itself, rather than the day after, stop and assess before continuing.

Frequently Asked Questions

Related Myths We’ve Busted

Gear Mentioned in This Article

As an Amazon Associate, Sarcastic Motivators earns from qualifying purchases.