As wisely stated in an editorial by Dr. George Brooks, UC Berkeley (2001), “Nature is smarter, and things are more complex than we mortals imagine.” Sure lactate is produced during exercise and is often blamed for causing muscles to fatigue, but there is much more to the story. In fact, research has shown that lactate plays many important physiological roles in the body such as serving as a metabolic fuel and aiding in communication between cells. A study by Nielson et al. (2001) also showed that the acidic effects of lactate actually help to counteract the increase in extracellular potassium ions that also happen during exercise and are attributed with causing muscle fatigue.  

Lactate can also control what fuels tissues use by inhibiting the breakdown of lipids in mammalian adipose and muscle tissues as well as increasing the breakdown of lipids in the liver to ultimately form new glucose molecules. In contrast, a new study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, showed that lactate does not appear have the same effects in rainbow trout. The research team discovered that instead of reducing the breakdown of lipids, lactate appears to reduce glucose production in the liver. To compensate for the reduction in glucose production, these fish use lactate as a fuel in most tissues, with the exception of white muscle tissue which has a limited ability to take up lactate.  

Sorry lactate, for all of the bad things we’ve said about you.

Sources:

GA Brooks. Lactate doesn’t necessarily cause fatigue: Why are we surprised? Journal of Physiology. 536(Pt 1): 1, 2001.

OB Nielsen, F de Paoli, K Overgaard. Protective effects of lactic acid on force production in rat skeletal muscle. Journal of Physiology. 536(Pt 1): 161-166, 2001.

GGM Talarico, E Thoral, E Farhat, L Teulier, JA Mennigen, JM Weber. Lactate signaling and fuel selection in rainbow trout: Mobilization of energy reserves. American Journal of Physiology – Regulatory, Integrative and Comparative Physiology. 325(5): R556-R567, 2023.

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Categories: Comparative Physiology, Diet and Exercise, Exercise, Nature's Solutions

Tags: American Journal of Physiology, American Physiological Society, fatigue, fitness, health, lactate, lactic acid, metabolism, performance, science, supplements, trout