Soreness is not a measure of a good session

Try three sets of walking lunges after six months away from them, at loads that would embarrass you on any other exercise, and you will spend two days taking stairs one at a time. The session achieved close to nothing. The soreness is spectacular.

Run it the other way. Week eight of a squat program, five kilos heavier than a fortnight ago, and you wake the next morning feeling like you did not train. That session moved you forward and left no trace.

The signal

Soreness tracks unfamiliarity. Hand a muscle a movement or a range it has not seen for a while and it complains for a day or two. Hand it the same demand next week and the complaint shrinks, then disappears, while the weight keeps climbing.

The effect has a name in the research, the repeated bout effect: the first exposure to a movement blunts the damage from the second. The protection arrives within a session or two, and it says nothing about whether the training is building anything.

DOMS explained

The formal name is Delayed Onset Muscle Soreness. It peaks 24 to 48 hours after training, which is why the day after a hard session can feel fine and the day after that is worse. The delay is the reason for the name and the reason people confuse it with injury.

The soreness comes from micro-damage to muscle fibres during the eccentric, or lowering, portion of a movement. The bottom of a squat, the descent on a bench press, the stretch at the bottom of a Romanian deadlift. Fibres lengthen under load, small structural damage occurs, and the body repairs the damage over the following days. The repair process is the adaptation. The soreness is a side effect of the repair, not a signal that something useful happened.

Two people can do the same session and experience different levels of DOMS. Genetics, hydration, sleep, training history and how much eccentric work the movement involves all change the response. A heavy set of leg curls might leave one person sore for a day and another sore for three, with no difference in the training effect. Using soreness to compare sessions, or to compare yourself to someone else, measures the wrong variable.

Why soreness fades over a block

The repeated bout effect protects the muscle within one to two exposures to the same movement. The first week of a new program produces the most soreness. By week two, the same exercises at the same or higher loads produce less. By week three or four, you stop getting sore from those movements at all, even as the weight on the bar continues to rise.

This protection is specific to the movement and the range of motion. Swap from a high-bar squat to a front squat and the soreness returns for a session or two, because the range and the muscle emphasis shifted. Go back to the high-bar squat a month later and it will produce soreness again, though less than the first time.

The protection lasts two to three weeks after you stop performing the movement. A two-week holiday from training is enough to reset part of the repeated bout effect, which is why the first session back from a break is often the sorest week of the year. The training effect from those previous months is still there. The protection against soreness is not.

Soreness fading is a feature of the design, not a flaw. The body has reinforced the tissue against that specific demand. The muscle is better prepared for the work. The load can increase. The fact that the mornings stop hurting is the adaptation doing its job.

When soreness means something

Sharp pain during a movement is not DOMS. DOMS is diffuse, spread across the belly of the muscle, and shows up a day or two later. A sharp or localised pain during a rep, in or around a joint, at the moment of exertion, is a different signal. Stop the exercise. If it reproduces on the next set, stop the movement for the session and note it in the log.

Soreness lasting more than four to five days after a session suggests the volume or the load was too high for what the muscle was prepared to handle. This is most common in the first week of a program, or after a long break, when enthusiasm exceeds conditioning. The fix is a lighter first week. Start with loads below what you expect to use, let the repeated bout effect establish itself, and push the numbers from week two onward.

Persistent soreness on one side, in the same spot, session after session, is an injury signal. Bilateral DOMS from squats hits both legs. If the left knee aches after every squat session and the right does not, the left knee is telling you something the right knee is not. Track it in the log. If it persists for more than two weeks, get it looked at before adding load.

The useful summary: DOMS is normal, fades on its own, and says nothing about session quality. Pain during a lift, soreness beyond five days, or one-sided complaints that do not resolve are worth attention. The logbook is where you track the difference.

The trap

Judge sessions by how sore they leave you and you will start picking whatever hurts. The thing that hurts most is the thing you have not done before: a new exercise this month, a new program the next.

Chase novelty and you stay sore while the bar stays where it started. Muscle grows when a familiar demand comes back heavier, and a familiar demand is the one thing a soreness-chaser refuses to serve twice.

The better ledger

Your log measures the session. It records the weight and the reps, and whether the pair beat last fortnight. Soreness measures how strange the session felt, and strange is cheap to manufacture.

An off day does less damage on paper too. A flat session at the planned loads still counts, sore or otherwise, and the page proves it a month later when the memory has gone soft.

By week eight of a good program the movements are familiar and the loads are the heaviest they have been. The mornings after feel unremarkable. That combination is the program working as written.

If you want a number to chase, chase the one in the log. It can climb for years. Soreness peaks in week one and has nothing left to say by week three.

Related reading: How hard is a hard set and Month one.

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