2023, Vol. 27 ›› Issue (2): 322-328

Exercise regulates lactic acid metabolism

Zhu Miaomiao1, 2, Kong Fanming1, Zhao Qian3   

Abstract: BACKGROUND: Blood lactic acid is one of the longest used and most widely used indicators in the field of sports science. It plays an important role in formulating training programs, controlling load intensity, and evaluating training effects.
OBJECTIVE: To re-examine the function and role of lactic acid, systematically review the latest developments in lactic acid metabolism in the field of sports science, summarize the biological mechanism of exercise regulating lipid oxidation, and look forward to the future research directions in this field.
METHODS: We searched for relevant literature in Bailian Cloud Library, PubMed and EBSCO Sports Science Full Text and Researcher and ResearchGate academic social platforms. The search terms included “exercise; lactic acid; lactic acid threshold; lactic acid metabolism; gluconeogenesis” in Chinese and English. Included documents were classified, summarized, and refined.
RESULTS AND CONCLUSION: Exercise-regulated lactic acid metabolism is a complex nonlinear process with the characteristics of stages. Exercise style, exercise intensity, exercise time, exercise level, age, sex, muscle fiber type, nutritional status, and environmental temperature are interrelated and mutually restricted. In essence, lactic acid is actually a biomarker of metabolic stress response, rather than an indicator of hypoxia in the body. It can be used as an important signaling molecule. Meanwhile, lactic acid is also an indispensable energy source and plays an important role in the process of gluconeogenesis. Lactic acid indicators have good effects on guiding and monitoring endurance training, but its validity is weak in monitoring strength qualities such as explosive power. Therefore, the use of lactic acid indicator should be individualized in sports practice combined with several indicators such as anaerobic threshold, heart rate, maximal oxygen uptake, creatine kinase, urine protein and creatinine whenever possible, so as to improve its scientificity and validity. There are many reasons for the production of lactic acid. Oxygen is not a necessary condition for the production of lactic acid, but changes in lactic acid are affected by oxygen supply in the body. The important reasons for the production of lactic acid include the increased rate of glycolysis, imbalance of lactic acid production and clearance, and large recruitment of fast-twitch fibers during exercise, which may be related to the ability of the respiratory system to take up oxygen, the ability of the heart to pump blood, the ability of the blood circulatory system to transport oxygen, and the ability of skeletal muscle to utilize oxygen. Regulation of lactic acid metabolism by exercise is a physiological and biochemical process involving multiple organs and nervous, exercise, circulatory, respiratory, digestive and endocrine systems.
Key words: exercise, lactic acid, lactic acid threshold, lactic acid metabolism, gluconeogenesis, review