Maximal oxygen uptake (VO2max) is used to define cardiorespiratory fitness, which is important to health and sport performance in humans. Although different types of training can improve VO2max, the high intensity interval training is recognized as one of the best ways to do it. Furthermore, it has long been speculated that high intensity interval training that elicits a high time spent near VO2max could be the best way to improve VO2max. However, this theory has not been verified. Thus, the investigators performed a randomized controlled trial with crossover in healthy individuals who underwent two high intensity interval training protocols of two weeks, being a workout with longer and other with shorter time spent near VO2max.
Fifteen participants were enrolled in a randomized trial with crossover to perform two weeks of high intensity interval training with high (i.e., five times 2 minutes of work and 1 minute of recovery; T-2min:1min) or low (i.e., ten times 1 minutes of work and 30 seconds of recovery; T-1min:30seg) time spent near VO2max. The work intensity was adjusted at 85% and 87% of power output achieved at the end of incremental test for the first and second week, respectively. Before and after the T-2min:1min and T-1min:30seg, the participants performed tests to determine VO2max, lactate threshold, muscle oxidative capacity, pulmonary oxygen uptake kinetics, power output achieved at the end of incremental test, and power output related to Wingate anaerobic test. The training programs had a washout period of at least one month.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
15
Two weeks of high intensity interval training with high or low time spent near VO2max.
University of the State of Santa Catarina
Florianópolis, Santa Catarina, Brazil
Maximal oxygen uptake
The highest 15 seconds VO2 average determined from rolling averages of 5 seconds samples measured during incremental test or confirmation test of VO2max.
Time frame: Change at Maximal oxygen uptake after two weeks
Lactate threshold
The work intensity at which blood lactate concentration increased 1 mmol.L-1 above baseline.
Time frame: Change at Lactate threshold after two weeks
Muscle oxidative capacity
Rate recovery of muscle oxygen consumption (k-mV̇O2) of the vastus lateralis, with the k-mV̇O2 indicating muscle oxidative capacity.
Time frame: Change at Muscle oxidative capacity after two weeks
Pulmonary oxygen uptake kinetics
The on-transient response for V̇O2 was fitted using a mono-exponential model, which the rate constant (k-pV̇O2) for the kinetics of V̇O2 was calculated as 1/tau (expressed in min-1).
Time frame: Change at Pulmonary oxygen uptake kinetics after two weeks
Power output achieved at the end of incremental test
Power output achieved at the end of ramp incremental test (20 W.min-1).
Time frame: Change at Power output achieved at the end of incremental test after two weeks
Wingate anaerobic test
Peak power, mean power, and minimum power were defined as the highest mechanical power output, the average power sustained throughout the 30-s period, and the power output attained before the end of the test, respectively.
Time frame: Change at Wingate anaerobic test after two weeks
Time spent near VO2max
Time spent at or above 90% or 95% of VO2max.
Time frame: First to the last day of test or training, an average of 4 weeks
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