For this week’s blog post I am discussing the idea that lactic acid accumulation during muscle activity is advantageous. Many people believe that lactic acid accumulation is the cause of muscle fatigue but this is not true and is supported by the information in the Point:Counterpoint article as well as a further reason study that I found.
The Point:Counterpoint article explains how there are a few main causes of muscle fatigue, none of them being accumulation of lactate. The authors describe muscle fatigue as a “disturbance to any of the steps in excitation-contraction (EC) coupling” (1410). Based on this definition, they then explain the types of muscle fatigue, which include a buildup of K+ in the T-system and metabolic fatigue. A buildup of K+ in the T-system depolarizes the fiber, which then slows or prevents the Na+ channels from recovering, and ultimately results in failure of action potentials. On the other hand, metabolic fatigue refers to the effects of metabolites and decrease in substrates. They even add that the slightly lowered pH as a result of lactate ions and high intracellular H+ seems to slow the onset of fatigue.
A research article that further the supports the idea of lactate having a positive impact rather than a negative one, describes an experiment performed on mice. They investigated mouse skeletal muscle tissue under the conditions of control, injected lactate, injected cardio toxin, and injected lactate after injected cardio toxin. The injections were performed 5 days a week for 2 weeks. The results showed that in the lactate group and lactate after cardio toxin group, there was an increase in muscle weight, fiber cross-sectional area, and facilitation of the recovery process as a result of the damages caused by the cardio toxin. These findings suggest that lactate can potentially stimulate muscle hypertrophy and/or the generation of muscle tissue and therefore support the idea that lactate accumulation is positive. Applied to exercise in humans, maybe the lactate helps to regenerate our muscle cells that get damaged from exercise such as weight lifting.
Ohno, Y.; Ando, K.; Ito, T.; Suda, Y.; Matsui, Y.; Oyama, A.; Kaneko, H.; Yokoyama, S.; Egawa, T.; Goto, K. Lactate Stimulates a Potential for Hypertrophy and Regeneration of Mouse Skeletal Muscle. Nutrients 2019, 11, 869. https://www.mdpi.com/2072-6643/11/4/869.
