Lactate kinetics at the lactate threshold in trained and untrained men.
Level 4 - case-series / case-control
Cross-sectional comparative physiological study between trained and untrained cohorts.
PubMed 23558389 · doi:10.1152/japplphysiol.00043.2013
What was done
Six untrained and six trained men completed 60-min exercise bouts at power outputs eliciting the lactate threshold (LT) to assess lactate kinetics (rates of appearance and disposal, and metabolic clearance rate [MCR]). Trained subjects completed two additional exercise bouts at 10% below the LT power output (LT-10%), one of which incorporated an exogenous lactate clamp to match blood lactate concentration to that measured during the LT trial.
What was found
At LT, lactate rate of appearance (Ra) was higher in trained (24.1 ± 2.7 mg·kg⁻¹·min⁻¹) than untrained men (14.6 ± 2.4 mg·kg⁻¹·min⁻¹; P < 0.05), but did not differ at matched relative intensity (67% VO2max). At LT, MCR was 34% higher in trained (62.5 ± 5.0 ml·kg⁻¹·min⁻¹) than untrained subjects (46.5 ± 7.0 ml·kg⁻¹·min⁻¹; P < 0.05). Reducing power output (LT-10%) increased MCR by 46% in trained men (91.5 ± 14.9 ml·kg⁻¹·min⁻¹; P < 0.05). At matched relative intensity (67% VO2max), MCR in trained subjects was 97% higher than in untrained subjects (P < 0.05). In the lactate clamp trial, MCR in trained subjects was 64% higher than in untrained subjects (P < 0.05).
Why it matters
This study shows that the lactate threshold reflects a limitation in metabolic clearance rate, which peaks below threshold, and demonstrates that endurance training enhances capacities for lactate clearance and disposal.
Limits
The study had a very small sample size (n = 12 total), included only male participants, and used a cross-sectional comparative design rather than a prospective training intervention.
Cited by
- supports Trained athletes produce more lactate than untrained individuals, but clear and remove it more rapidly.