Effects of Training on Lactate Kinetics Parameters and their Influence on Short High-Intensity Exercise Performance

Abstract The purpose of the present study was to relate the training-induced alterations in lactate kinetics parameters to the concomitant changes in time to exhaustion (T lim ) at a work rate corresponding to maximal oxygen uptake (Pa peak ). Eight subjects performed before and after training i) an incremental exercise up to exhaustion to determine Pa peak , ii) a 5-min 90 % Pa peak exercise followed by a 90-min passive recovery to determine an individual blood lactate recovery curve fitted to the bi-exponential time function: La(t) = La(0) + A 1 (1 - e -γ1 · t ) + A 2 (1 - e -γ2 · t ), and iii) a time to exhaustion at Pa peak to determine T lim . A biopsy of the vastus lateralis muscle was made before and after training. The training programme consisted in pedalling on a cycle ergometer 2 h a day, 6 days a week, for 4 weeks. Training-induced increases (p < 0.05) in Pa peak , muscle capillary density, citrate synthase activity, γ 2 that denotes the lactate removal ability (from 0.0547 ± 0.0038 to 0.0822 ± 0.0071 min -1 ) and T lim (from 299 ± 23 to 486 ± 63 s), decreases (p < 0.05) in activities of lactate dehydrogenase (LDH) and muscle type of LDH, the phosphofructokinase/citrate synthase activities ratio and the estimated net amount of lactate released (NALR) during exercise recovery (from 66.5 ± 8.6 to 47.2 ± 11.1 mmol) were also observed. The improvement of T lim with training was related to the increase in γ 2 (r = 0.74, p = 0.0367) and to the decrease in NALR (r = 0.77, p = 0.0250). These results suggest that the post-training greater ability to remove lactate from the organism and reduced muscle lactate accumulation during exercise account for the concomitant improvement of the time to exhaustion during high-intensity exercise performed at the same relative work rate.