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Lactic acid, often vilified for causing muscle fatigue and soreness after a workout, might actually be innocent, if experts and research are anything to go by.
“Muscles becoming sore during physical activity result from muscle fatigue and hypersensitization of nerve endings, which relates more to the nervous system,” says Christopher Pedra, consultant, sports and exercise medicine, Sir HN Reliance Foundation Hospital, Mumbai. “However, the soreness felt sometime after exercising, which usually peaks between 24 to 72 hours, is referred to as DOMS [delayed onset muscle soreness]. This typically results from microscopic muscle damage [small tears in the muscles] that occurs when you push them really hard. Subsequently, that part of your body gets stronger as it adapts and makes stronger muscle fibers.”
DOMS and lactic acid
Lactic acid — produced when muscles work hard without sufficient oxygen during intense exercise — was believed to be the reason behind DOMS or post-exercise muscle fatigue. However, various research studies have disproved this notion. Lactic acid is swiftly cleared out of your muscles and reintroduced into circulation; it can also be used as energy once you catch your breath.
“When you are active, your cells break down glucose for energy. However, lactate, the ‘waste product’ of that process, can also produce energy on its own,” says Pedra. “Certain tissues in your body, like your brain, liver, muscles and heart, can utilize those lactate molecules directly for energy. In addition, they can also get transported back to the liver, converted into pyruvate [byproduct of glucose metabolism] and then back to glucose for circulation. So, it is not something that needs to be cleared from your system,” he explains.
In a research paper published in the journal The Physician and Sportsmedicine, Schwane JA et al tested the veracity of the idea that DOMS after running is caused due to lactic acid build-up. Blood lactic acid levels of the participants were measured before, during and after running on a treadmill (both level and inclined). In addition, they were asked to rate the muscle soreness at different time intervals (24, 48 and 72 hours) after running. Results revealed that lactic concentrations did not increase in the runners despite the onset of soreness, indicating that it is not related to exercise-induced DOMS.
Massages and lactic acid
While massages can provide relaxation and temporary relief from muscle soreness by improving blood flow and reducing muscle tension, there’s little to no scientific evidence to support the notion that they effectively clear lactic acid from muscles.
“Your body maintains a state of homeostasis, retaining a specific level of lactate in your bloodstream. This can increase to many times its normal concentration in case of submaximal exercise,” says Pedra.
Lactic acid is typically cleared from the body through natural processes like blood circulation and metabolism. “People rely on massages and other random techniques to clear out lactic acid, as they believe that its presence in the body is not healthy. However, this is not true. Your body reduces the elevated lactate concentration back to its normal resting level by either using it as energy or clearing it out about an hour after your workout session,” says Pedra.
Takeaways
- According to experts and research, lactic acid is not responsible for causing muscle soreness and fatigue after exercise.
- Lactate can produce energy on its own, which can be used by several tissues like the brain, liver, muscles and heart.
- Lactic acid is typically cleared from the body through natural processes like blood circulation and metabolism; massages have little impact on it.
