期刊
JOURNAL OF APPLIED PHYSIOLOGY
卷 114, 期 11, 页码 1593-1602出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/japplphysiol.00043.2013
关键词
exercise; maximal lactate steady state (MLSS); exertion; endurance training; lactate oxidation; gluconeogenesis from lactate; intermediary metabolism
资金
- France-Berkeley Fund
To understand the meaning of the lactate threshold (LT) and to test the hypothesis that endurance training augments lactate kinetics [i.e., rates of appearance and disposal (R-a and R-d, respectively, mg.kg(-1).min(-1)) and metabolic clearance rate (MCR, ml.kg(-).min(-1))], we studied six untrained (UT) and six trained (T) subjects during 60-min exercise bouts at power outputs (PO) eliciting the LT. Trained subjects performed two additional exercise bouts at a PO 10% lower (LT-10%), one of which involved a lactate clamp (LC) to match blood lactate concentration ([lactate](b)) to that achieved during the LT trial. At LT, lactate R-a was higher in T (24.1 +/- 2.7) than in UT (14.6 +/- 2.4; P < 0.05) subjects, but R-a was not different between UT and T when relative exercise intensities were matched (UT-LT vs. T-LT-10%, 67% V. O-2max). At LT, MCR in T (62.5 +/- 5.0) subjects was 34% higher than in UT (46.5 +/- 7.0; P < 0.05), and a reduction in PO resulted in a significant increase in MCR by 46% (LT-10%, 91.5 +/- 14.9, P < 0.05). At matched relative exercise intensities (67% VO2max), MCR in T subjects was 97% higher than in UT (P < 0.05). During the LC trial, MCR in T subjects was 64% higher than in UT (P < 0.05), in whom % VO2max and [lactate](b) were similar. We conclude that 1) lactate MCR reaches an apex below the LT, 2) LT corresponds to a limitation in MCR, and 3) endurance training augments capacities for lactate production, disposal and clearance.
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