Blood Lactate Steady State During High Intensity Interval Training Could Be Sustained Over Continuous Maximal Lactate Steady State

Abstract

BACKGROUND Several researches have described Maximal Lactate Steady State (MLSS) as a highest level of Blood Lactate (BLa) that a subject is able to sustain in steady state (SS) condition, with BLa variation no more than 1 mM, during 10 to 30 minutes of continuous prolonged exercise. However, there is little evidence of SS at high intensity interval training (HIIT), with previous studies showing higher BLa levels compared with continuous MLSS tests. Our previous work suggests that moderate SS levels (4-7 mM) can be sustained during Interval Training with passive rest (PR) of 60s. PURPOSE: Unlike to the previous design, the objective of this research is to observe BLa SS (during whole workout) at HIIT, using PR of 180 s. METHODS: Ten trained swimmers (19.0 ± 3.7 y) performed HIIT (BLa ~9 mM). The series was 6x100m freestyle with 180 s PR. BLa and heart rate (HR) were measured at 10s, 50s, 110 s and 170 s at the same time during PR every 2 reps. We applied Shapiro-Wilk test to analyze for normality. We compared BLa and HR applying Friedman test (p < 0.05) in reps 2, 4, and 6. For time performance, we applied repeated measures ANOVA (p < 0.05) in all reps. Also we determine Pearson (r) or Spearman (rs) correlation coefficient between BLa and HR. RESULTS: The mean BLa max/min were 10.01 and 8.21 mM, respectively. The time performance was 63.97 ± 3.42 sec. and non-significant differences were found between all reps. Also, we found no r/rs between BLa vs. HR at same times.CONCLUSION: Despite the significant differences between BLa during 180s PR, BLa is maintained within 8 to 10 mMol/l during whole workout. BLa did not increase more than 1.05 mM between 10 to 24 minutes from rep. 4 to 6. These SS BLa levels are larger than previously published continuous MLSS. In addition, time performance was not changed during the series. Finally, we found that HR is not valid variable to control metabolic stress during HIIT.