Oxidative removal of lactate after strenuous exercise.
Level 5 - mechanism / opinion, no new human data
Animal research (rats and mice)
PubMed 2400462 · doi:10.2114/ahs1983.9.213
What was done
Metabolic fate of lactate following 2-3 minutes of strenuous exercise was investigated in rats and mice. 14C-labeled lactate or glucose was injected into the aorta of rats via catheter. 14C-glucose was injected intraperitoneally into mice after supramaximal exercise. Mice ran twice with a 4-hour interval to evaluate muscle 14C-lactate metabolism derived from muscle 14C-glycogen.
What was found
No numerical values, percentages, or statistical tests are reported in the abstract. A large amount of blood and muscle 14C-lactate was expired as 14CO2, indicating that oxidative removal is the major metabolic fate of lactate after strenuous exercise. Blood glucose served as the major substrate for muscle glycogen resynthesis. Intramuscular gluconeogenesis from lactate to glycogen was not a major pathway, though high-intensity training activated it. Light-intensity exercise after strenuous exercise (active recovery) enhanced oxidative removal of blood and muscle lactate.
Why it matters
This study provides mechanistic tracer evidence in rodents that lactate is primarily oxidized rather than converted directly back into muscle glycogen after intense exertion, supporting the physiological rationale for active recovery.
Limits
Conducted exclusively in animal models (rats and mice), limiting direct translation to human athletes or clinical populations. The abstract omits sample size, numerical clearance rates, kinetic measurements, and variance.
Cited by
- partial Carbohydrates converted to lactate or pyruvate during anaerobic exercise are ultimately fully metabolized in the mitochondria through oxidation.