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Updated: Mar 16, 2026
A Real-World High-Intensity Interval Training Protocol for Cardiorespiratory Fitness Improvement
Published on: February 22, 2022
Short-term interval training at both lower and higher intensities in the severe exercise domain result in
Tiago Turnes1, Rafael Alves de Aguiar2, Rogério Santos de Oliveira Cruz2
1Human Performance Research Group, Center for Health and Sport Science (CEFID), Santa Catarina State University (UDESC), Pascoal Simone, 358, Coqueiros, Florianópolis, SC, CEP 88080-350, Brazil. tiagoturnes89@gmail.com.
Purpose:
Although high-intensity interval training (HIT) seems to promote greater improvements in aerobic parameters than continuous training, the influence of exercise intensity on [Formula: see text] on-kinetics remains under investigation.
Methods:
After an incremental test, twenty-one recreationally trained cyclists performed several time-to-exhaustion tests to determine critical power (CP), and the highest intensity (I HIGH), and the lowest exercise duration (T LOW) at which [Formula: see text] is attained during constant exercise. Subjects also completed a series of step transitions to moderate- and heavy-intensity work rates to determine pulmonary [Formula: see text] on-kinetics. Surface electromyography (EMG) of vastus lateralis muscle and blood lactate accumulation (∆BLC) was measured during heavy exercise. Subjects were assigned to one of two 4-week work-matched training groups: the lower [105 % CP: n = 11; 4 × 5 min at 105 % CP (218 ± 39 W), 1 min recovery] or the upper [I HIGH: n = 10; 8 × 100 % I HIGH (355 ± 60 W), 1:2 work:recovery ratio] intensity of the severe exercise domain.
Results:
The two interventions were similarly effective in reducing the phase II [Formula: see text] time constant during moderate (105 % CP: 34 ± 13 to 25 ± 8 s; I HIGH: 31 ± 9 to 23 ± 6 s) and heavy exercise (105 % CP: 25 ± 7 to 18 ± 5 s; I HIGH: 27 ± 7 to 16 ± 5 s) and in reducing the amplitude of [Formula: see text] slow component, EMG amplitude, and ∆BLC during heavy exercise.
Conclusion:
In conclusion, the short-term adjustments in response to step transitions to moderate and heavy exercise were independent of training intensity within the severe exercise domain.
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