Maximal Power Output Estimates the MLSS Intensity in Cycle Ergometer Before and After Aerobic Training

Abstract

The maximal blood lactate steady-state intensity (MLSS) is considered the gold standard method for determining lactate threshold, aerobic capacity evaluation and training prescription. However, the method is expensive and demands practice and knowledge to data collection and blood handling. PURPOSE: To establish an equation to predict MLSS intensity through a validated VO2max incremental test protocol in cycle ergometer. METHOD: Twenty-six physically active men (age 24 ± 3y, body mass 73.4±6.7kg, VO2max 49,3 ± 6,1 mL.kg-1.min-1) were randomly divided into two groups (G1 and G2). All subjects performed an incremental test until fatigue to determine the maximum power output (WMAX) and VO2MAX (25W.2min-1) cycling at 50rpm and two to five constant intensity tests lasting 30 minutes (CT) to determine MLSS. In CT, MLSS was considered the greater intensity of 30min cycling without blood lactate increase (Δ<1mM) during the last 20 min of exercise. All the tests were performed in a mild environment (22°C and 50% RH). Then subjects in the G2 underwent six weeks of aerobic training at the MLSS intensity, and after the training period the subjects repeated all the pre training tests. A regression equation was established from the G1 volunteers WMAX and WMFEL to estimate the MLSS, for a significant level of p<0.05. This equation was used to estimate the MLSS intensity before and after the aerobic training for G2. RESULTS: The established equation was: WMFEL-EST = 0.866xWMAX+41.73. A high correlation between WMAX and WMFEL was found for G1(r=0.95, p<0.05). WMAX (219±29 pre and 252±28 W post; p<0.01) and WMFEL (150±27 pre and 171±26W post; p<0.01) in G2 were higher after the training period compared to pre training. Besides, no differences and significant correlations were found between the measured and the estimated WMFEL values before (measured 150±27 and estimated 148±27W; p>0.05) (r=0.70; p<0.05) and after the training period (measured 171±26 and estimated 177±24 W; p>0.05) (r=0.79; p<0.05). CONCLUSION: The proposed equation (WMFEL-EST = 0.866xWMAX+41.73) was able to estimate the MLSS power output before and after six weeks of aerobic training. Therefore it would be possible to use only one test to obtain both measured VO2max and estimated WMFEL in young, physically active individuals before and after an aerobic training period.