Myth Busters: Does Massage Really "Flush Lactic Acid" From Muscles?

The Claim

Few phrases are repeated as often in gyms and treatment rooms as the idea that a post-exercise massage "flushes out the lactic acid" that has built up in tired, sore muscles — as though lactate were a kind of metabolic sludge that pools in tissue and must be physically pushed along by manual pressure before the muscle can recover.

What Lactate Actually Is

Lactate is produced continuously during glycolysis, the process by which muscle converts glucose into usable energy, and its production rises sharply during high-intensity exercise as the demand for ATP outstrips the rate at which oxidative metabolism alone can supply it. Far from being a waste product, lactate is now understood to be an important fuel: it is shuttled between tissues — and back to the liver for conversion to glucose via the Cori cycle — and can be taken up directly by the heart, brain and other skeletal muscle fibres as an energy substrate (Brooks, 2018, in the broader lactate shuttle literature this site's research draws on).

Critically, lactate clearance from the blood after exercise is fast. Blood lactate concentrations typically return to near-resting levels within 30 to 60 minutes of cessation of intense exercise, largely through ongoing oxidative metabolism, well before a client is likely to be lying on a treatment table.

What the Trials Actually Show

This leaves very little physiological work for massage to do with respect to lactate specifically — and the research bears this out. A 2023 systematic review of 114 studies on massage and exercise performance concluded plainly that massage "did not change blood lactate clearance, muscle blood flow, muscle temperature, or activation" (Dakić et al., 2023). An earlier controlled trial examining leg massage after repeated high-intensity cycling bouts found no measurable effect of massage on blood lactate concentration compared with passive recovery, though it did find a modest improvement in a subsequent fatigue index (Robertson, Watt & Galloway, 2004) — a benefit the authors attributed to factors other than lactate removal.

So Why Does Soreness Happen, Then?

If lactate isn't lingering in sore tissue, what explains delayed onset muscle soreness (DOMS)? The dominant explanation involves microscopic structural disruption of muscle fibres — particularly from unaccustomed eccentric loading — followed by a local inflammatory response involving calcium influx, protease activity and sensitisation of local nociceptors. This process unfolds over 24 to 72 hours, which is precisely why soreness is delayed rather than immediate: a lactate-based explanation would predict soreness peaking during or immediately after exercise, when lactate concentration is highest, not two days later when it has long since returned to baseline.

The Verdict