The Effects of High vs. Low Time Spent Near VO2max During Two Work-matched High Intensity Interval Training.

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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The Effects of High vs. Low Time Spent Near VO2max During Two Work-matched High Intensity Interval Training.

Conditions
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VO2max

Intervention / Treatment
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* Other: Exercise training


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male ≥ 18 years; No known musculoskeletal disorders; Apparently healthy Physically active according to American College of Sports Medicine standards and recommendations (Garber et al., 2011; RIEBE et al., 2015). Exclusion Criteria: Taking any medication that could affect aerobic parameters; Smokers; Involved in an aerobic training program at the start of the study.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: The order of training protocols was randomized and the training programs had a washout period of at least one month.
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: High intensity interval training with high time spent near VO2max<br>Participants performed high intensity interval training with high time spent near VO2max three times a week for two weeks. All training sessions consisted of five times 2 minutes of work and 1 minute of passive recovery. 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. The training sessions were performed using cycle ergometer. Findings were compared to high intensity interval training with low time spent near VO2max, which followed the same exercise frequency, intensity and total duration. | Other: Exercise training<br>* Two weeks of high intensity interval training with high or low time spent near VO2max.<br>|
| Experimental: High intensity interval training with low time spent near VO2max<br>Participants performed high intensity interval training with low time spent near VO2max three times a week for two weeks. All training sessions consisted of ten times 1 minutes of work and 30 seconds of passive recovery. 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. The training sessions were performed using cycle ergometer. Findings were compared to high intensity interval training with high time spent near VO2max, which followed the same exercise frequency, intensity and total duration. | Other: Exercise training<br>* Two weeks of high intensity interval training with high or low time spent near VO2max.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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. | Change at Maximal oxygen uptake after two weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Lactate threshold | The work intensity at which blood lactate concentration increased 1 mmol.L-1 above baseline. | 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. | 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). | 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). | 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. | Change at Wingate anaerobic test after two weeks | 
| Time spent near VO2max | Time spent at or above 90% or 95% of VO2max. | First to the last day of test or training, an average of 4 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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VO2max, Exercise, Aerobic, Performance, Training