Issue link: https://www.massageandbodyworkdigital.com/i/77400
SOMATIC RESEARCH twice—once when presented as a poster at a conference, and secondly after publication in a journal. Ouch. WHAT IS LACTIC ACID? The search for the cause of muscle soreness and fatigue began more than a century ago. In the late 19th century, fermentation chemists realized that juice left to ferment without adequate oxygen resulted in acid products. In the early 20th century, when physiologists stimulated isolated frog muscles to contract until exhaustion, they found that the tissues had accumulated high amounts of lactic acid. Since then, the idea that lactic acid accumulation causes muscle fatigue has persisted.4 More recently, the lactic acid paradigm has shifted. Lactic acid is understood to be more than just a waste product of exercise. Lactic acid is the result of the glycolytic energy production system. In other words, muscles make lactic acid to fuel cells not only in the muscle that produced the lactate, but also as an energy source that can be shuttled off to adjacent muscle cells for fuel. Lactic acid has also been found to fuel fibers in the heart and cells in the brain. The liver prefers to use lactic acid to make glucose for the blood when exercise is prolonged. The production of lactic acid is stimulated, in part, by circulating adrenalin; the combination of adrenalin and lactic acid helps protect against the electrolyte imbalance across muscle membranes brought on by the loss of potassium.5 Lactic acid is not simply the end result of an oxygen-deprived muscle, accumulating and resulting in muscle fatigue and soreness. Rather, it is an important intermediary in numerous metabolic processes and pathways within and between cells. It is a central player in cellular, regional, and whole body metabolism. The original cell- to-cell lactate shuttle explaining muscle and exercise metabolism has escalated to include lactic acid as a key contributor of energy supporting nearly every metabolic function in the body.6 Another group of scientists explain the link between oxygen-based aerobic metabolism and oxygen-free anaerobic metabolism. Muscle cells use carbohydrates anaerobically for energy, producing lactate as a byproduct, but then burn the lactate with oxygen to create far more energy. During normal exertion, the lactate seeps out of the muscle cells into the blood to be used elsewhere. During intense exercise, the rapidly accumulating lactate is burned more rapidly to create more energy. Endurance training teaches the body to efficiently use lactic acid as a source of fuel on par with carbohydrates stored in muscle tissue and sugar in blood. Efficient use of lactic acid not only prevents lactate buildup, but ekes out more energy from the body's fuel.7 Physicist and massage therapist Keith Eric Grant, PhD, offered an interesting analogy for lactic acid in the email exchange mentioned earlier: "The picture of lactate that emerges is much like that of charcoal to wood. Lactate is not a waste product but a further metabolic participant and source of fuel to muscles. As charcoal is partially oxidized wood, lactate is partially burnt fuel." THE ROLE OF MASSAGE IN MUSCLE RECOVERY Now that we understand that lactic acid is not waste to be flushed out of the muscles, what is the cause of muscle soreness and fatigue and what role do we have in relieving those post-exercise symptoms? We know that training helps people burn lactic acid more efficiently by growing the mitochondria in muscle cells. The mitochondria are where the lactate is burned for energy. Intense exercise, particularly interval training, generates big lactate loads, and the body adapts by building up mitochondria to clear lactic acid quickly. Overtraining, on the other hand, can kill muscle cells.8 We know that delayed onset muscle soreness (DOMS) is the pain or discomfort often felt 24–72 hours after eccentric contraction exercise or exertion accompanied by unaccustomed training levels—once thought to be caused by lactic acid buildup but now attributed to inflammation and micro-tears in the muscle fibers, fascia, and nociceptors.9 The research says massage reduces soreness and swelling in athletes post-exercise, and significantly reduces pain in people experiencing DOMS by as much as 25–50 percent.10 The research literature to date is insufficient to conclude whether massage facilitates recovery from a fatiguing effort. Both tissue healing and a psychological effect of massage are areas that may prove promising with further research. Results from published literature support a positive trend for massage to benefit athletic recovery and performance, and a need for further study is warranted.11 REFORM OUR CLAIM While we do not yet understand the mechanisms involved in the reduction of soreness and decreased swelling through the application of massage therapy, we can confidently say those are benefits of massage, not just for athletes but for anyone suffering from pain or inflammatory conditions. Resist the urge to explain the statement "massage can significantly reduce pain and swelling" and simply and confidently assert the truth. In the meantime, encourage researchers to continue to explore how massage works, and what effects massage might have on fatigue and tissue healing. 120 massage & bodywork march/april 2011