Endurance training affects lactate clearance, not lactate production.
Level 5 - mechanism / opinion, no new human data
Animal physiological experiment
PubMed 6401405 · doi:10.1152/ajpendo.1983.244.1.E83
What was done
Primed-continuous infusions of [2-3H]- and [U-14C]lactate were used to measure lactate kinetics in endurance-trained rats (running 2 h/day at 29.4 m/min up a 15% gradient) and untrained controls. Measurements were taken at rest, during easy exercise (13.4 m/min, 1% gradient), and during hard exercise (26.8 m/min, 1% gradient). Blood lactate concentration, lactate turnover rates, and metabolic clearance rates were determined.
What was found
Blood lactate in trained rats was 1.0 +/- 0.09 mM at rest, 1.64 +/- 0.21 mM during easy exercise, and 2.66 +/- 0.38 mM during hard exercise, compared with control values of 1.93 +/- 0.21 mM (easy) and 4.62 +/- 0.57 mM (hard). Lactate turnover with [U-14C]lactate rose from 214.0 +/- 17.0 mumol.kg-1.min-1 at rest to 390.3 +/- 31.6 at easy exercise and 518.1 +/- 56.4 at hard exercise, with no significant differences between trained and control animals across any condition. [2-3H]lactate turnover followed identical patterns but yielded values 90% higher than [U-14C]lactate. Metabolic clearance rate did not differ at rest (180.6 +/- 27.7 ml.kg-1.min-1), but trained rats showed 37% and 107% greater clearance rates than controls during easy and hard exercise, respectively.
Why it matters
This study showed that endurance training attenuates circulating lactate accumulation during exercise by enhancing its metabolic clearance from the blood rather than reducing its rate of production.
Limits
The study was conducted in a rodent model, limiting direct translation to human exercise physiology. Sample size (n) was not reported in the abstract, resting baseline lactate for control animals was omitted, and the specific tissues responsible for the increased clearance were not quantified.
Cited by
- supports Endurance training leads to lower blood lactate at any given power output because trained individuals have superior lactate clearance and utilization.