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Revista Brasileira de Medicina do Esporte
Print version ISSN 1517-8692
LUCAS, Ricardo Dantas de; ROCHA, Renato; BURINI, Roberto Carlos and DENADAI, Benedito Sérgio. Comparison of the exercise intensity at lactate minimum, lactate threshold, and anaerobic threshold during bicycle exercise with endurance athletes. Rev Bras Med Esporte [online]. 2000, vol.6, n.5, pp.172-179. ISSN 1517-8692. http://dx.doi.org/10.1590/S1517-86922000000500002.
The objective of this study was to compare the exercise intensity at lactate minimum (LACmin), with the intensity corresponding to lactate threshold (LT) and anaerobic threshold (AT). Eleven male athletes (age, 22.5 + 3.17 yr.; height, 172.3 + 8.2 cm; weight, 66.9 + 8.2 kg; and body fat, 9.8 + 3.4 %), participated in this study. The individuals performed two tests in an electromagnetic cycle (Quinton - Corival 400): 1) progressive load test - initial load of 100 W, with increments of 25 W to volitional fatigue; and 2) lactate minimum test - initially the individuals performed two supramaximal boats (+ 120% max) for 30 seconds, with 1-min. rest interval between boats to induce hyperlactemia. After 8 min. of passive recovery, individuals began a progressive load test, identical to that previously described. LT and AT were identified as the smallest values among the ratio - blood lactate (mM) : exercise intensity (W), and the intensity corresponding to 3.5 mM of blood lactate, respectively. The LACmin intensity (the intensity corresponding to the nadir on the blood lactate versus intensity plot) was determined from the zero gradient tangent to a spline function fitting the blood lactate data derived from the incremental part of the test. No significant difference was observed among the power at the LT (197.7 + 20.7 W) and LACmin (201.6 + 13.0 W), being both significantly lower than AT (256.7 + 33.3 W). There were no significant differences for the (ml.kg-1.min-1) and HR (bpm) obtained at the LT (43.2 + 5.01; 152.0 + 13.0) and LACmin (42.1 + 3.9; 159.0 + 10.0), being however significantly lower than that obtained at the AT (52.2 + 8.2; 174.0 + 13.0, respectively). It can be concluded that the LACmin test, under the condition of this investigation, can underestimate the intensity of MSSLAC (indirectly assessed by AT), which is consistent with other studies that determined MSSLAC directly. Thus, more studies are necessary to access the possible time-dependant component (initial intensity) that may exist in the LACmin test.
Keywords : Lactate minimum; Lactate threshold; Anaerobic threshold; Cycling.