Blood lactate accumulation during exercise in older endurance runners

To delineate the possible age-related differences in blood lactate response during exercise and its relations to endurance performance, 34 male runners (aged 21 to 69 years) performed an incremental treadmill running test. There were no significant differences in training distance and relative body fat among younger runners (YR), middle-aged runners (MR), and older runners (OR). The 5-km run time slowed with age, but was ranked at relatively the same level in each age group. OR had a 23% (P < 0.001) and 12% (P < 0.01) lower maximal oxygen uptake (V̇O₂max) and a 22% (P < 0.001) and 11% (P < 0.001) slower 5-km run time than YR and MR, respectively. However, mean V̇O₂ corresponding to a 4 mM of blood lactate (OBLA V̇O₂) was the same among the groups when expressed as %V̇O₂max (YR; 84.3%, MR; 85.9%, OR; 85.9%). Significant correlations were found between OBLA V̇O₂(ml·kg^-1·min^-1) and 5-km run time in each group (YR; r = -0.648, P < 0.05; MR; r = -0.658, P < 0.01; OR; r = -0.680, P < 0.05). These results suggest that OR attain a given blood lactate level at almost similar %V̇O₂max to YR and MR and that OBLA V̇O₂ in OR is useful for evaluating an endurance performance as well as in YR and MR.