The purpose of this study was to confirm that blood lactate concentrations can be maintained at moderate to high steady state values during an entire interval training (IT) session (repetitions + rest). Forty-eight trained swimmers and track athletes performed four IT protocols consisting of 6-10 bouts between 1 and 3-min at ~5-10 mmol/L blood lactate concentrations with a passive recovery of 60 to 180-sec. Performance times were measured at every bout, while blood lactate concentrations and heart rate during recovery every other bout. One-way ANOVA was performed for comparisons and r-squared for the effect size (ES). Performance times were stable throughout each IT protocol (75 ± 8 and 77 ± 5-sec [swimmers and track athletes]; 67 ± 3-sec [swimmers]; 64 ± 3-sec [swimmers]; and 135 ± 6-sec [swimmers]). Despite some minor differences (p<0.05; ES, 0.28 to 0.37, large), blood lactate concentrations were maintained stable at moderate to high values during each IT protocol (5.85 ± 1.47 mmol/L; 5.64 ± 1.03 mmol/L; 9.29 ± 1.07 mmol/L; and 9.44 ± 1.12 mmol/L). HR decreased significantly from the beginning to the end of recovery (p<0.05; ES, 0.93 to 0.96, large). In conclusion, moderate to high blood lactate steady state concentrations can be sustained for ~20 to 60-min during an entire IT session (repetitions + rest) at a stable performance. This approach can optimize performance by stimulating the metabolic demands and the pace strategy during the middle section of endurance competitive events.
Keywords: Interval exercise; endurance exercise; endurance performance; maximal lactate steady state.