Is the high lactate release during arm exercise due to a low training status?

To determine whether arm lactate release during arm exercise is related to the training status of the arms, seven arm-trained athletes were studied during 30 min of continuous arm exercise (AE) or leg exercise (LE) of increasing intensities corresponding to 30%, 50%, and 80% of peak VO2 during AE and LE respectively. Blood vessels were catheterized for determination of regional blood flows and substrate exchanges. The respiratory exchange ratio was higher during AE than LE (P less than 0.01). The arteriovenous oxygen difference, (A-V)O2, for the leg during LE was 11-19% higher than the (A-V)O2 for the arm during AE (P less than 0.01). At the highest intensity the (A-V)O2 was 170 +/- 6 ml O2l-1 during LE, vs. 143 +/- 9 during AE (P less than 0.01). Arm blood flow in relation to limb volume was 56-95% higher during AE (P less than 0.05). Arterial lactate concentrations were 27-60% higher during AE (P less than 0.01) and lactate release from the exercising limb was 2-4 times higher (P less than 0.05) during AE compared to LE. Adrenaline and noradrenaline rose 6- and 21-fold, respectively, during AE and did not differ from corresponding LE values. During AE the (A-V)O2 difference across the arm, arterial lactate concentration, and arm lactate release were of the same magnitude in arm-trained and relatively less arm-trained subjects. Lactate release in relation to O2 uptake by the exercising limb was 7-37% lower during AE in arm-trained subjects compared to AE in arm-untrained subjects but was 3-6 times higher than the corresponding relation during LE (P less than 0.01). We conclude that AE is associated with a larger lactate release compared to LE. This difference is only to a minor extent influenced by intense training of the arms. The high arm vs. leg lactate release appears to be associated with differences in regional circulatory adaptation by the exercising limb.