Interval training in the boundaries of severe domain: effects on aerobic parameters

Abstract

Purpose

Although time spent at $\dot{V}$O₂max (t@$\dot{V}$O₂max) has been suggested as an optimal stimulus for the promotion of greater $\dot{V}$O₂max improvements, scientific findings supporting this notion are surprisingly still lacking. To investigate this, the present study described t@$\dot{V}$O₂max in two different severe-intensity interval training regimens and compared its effects on aerobic indexes after a 4-week intervention.

Methods

Twenty-one recreational cyclists performed an incremental exercise test and six time-to-exhaustion tests on four different days to determine $\dot{V}$O₂max, lactate threshold (LT), critical power (CP) and the highest intensity (I _HIGH) and lowest exercise duration (T _LOW) at which $\dot{V}$O₂max was attained. Subjects were assigned to the lower (LO, n = 11, 4 × 5 min at 105 % CP, 1 min recovery) or the upper severe-intensity training groups (UP, n = 10, 8 × 60 % T _LOW at 100 % I _HIGH, 1:2 work:recovery ratio). t@$\dot{V}$O₂max was measured during the first and last training sessions.

Results

A significantly higher t@$\dot{V}$O₂max was elicited in the UP during training sessions in comparison with the LO group (P < 0.05), and superior improvements were observed in $\dot{V}$O₂max (change in measure ±95 % confidence interval) (6.3 ± 1.9 vs. 3.3 ± 1.8 %, P = 0.034 for interaction terms) and LT (54.8 ± 11.8 vs. 27.9 ± 11.3 %, P = 0.023 for interaction terms). The other aerobic indexes were similarly improved between the groups.

Conclusion

The present results demonstrated that UP training produced superior gains in $\dot{V}$O₂max and LT in comparison with LO training, which may be associated with the higher t@$\dot{V}$O₂max.