Effects of High Intensity Interval Training (HIIT) vs. Inspiratory Muscle Training on the Recovery After a Maximal Apnea.

Study Overview
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Brief Summary
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The aim of this randomized cross-over controlled study was to assess the effects of an 4-week exercise program on the recovery capacity after a voluntary maximal apnea. Participants will be randomly allocated to receive either a high intensity interval training (HIIT), or an inspiratory muscle training (IMT) using an inspiratory resistance device.

Detailed Description
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It is a multi-center study. 3 different Spanish Freedivers Centres are included in the study (Madrid, Zaragoza, and Barcelona). For each participant, exercise program started with one or the other program. Hence, both interventions were applied once with the participant randomly allocated to receive the same intervention. The trial included four study visits. Each exercise training program will be applied sessions per week during 4 weeks. Participants received baseline assessments at the beginning of nay intervention, and post-intervention assessments at the end of the fourth week. The wash-out period will be two weeks. After these two weeks participants switched intervention.

Official Title
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Effects of Inspiratory Muscle Training vs. High Intensity Interval Training Program on the Recovery Capacity After a Maximal Dynamic Apnea in Breath-hold Divers. A Randomized Crossover Trial

Conditions
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Exercise Training, Respiratory Muscle Training, High-Intensity Interval Training, Apnea

Intervention / Treatment
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* Other: High intensity interval training
* Other: Inspiratory muscle training


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Absence of pain or illness No changes in cognitive ability Over 18 years old. Member of the Spanish Federation of Underwater Activities. Positive medical examination that allows the diver to practice voluntary apnea. Exclusion Criteria: People with systemic diseases, tumors, infections, pacemakers, history of epilepsy, hydrophobia, pregnancy women, pharmacological treatment. To be participating in other physical activities during the experimental research

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

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: Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: High intensity interval training<br>It will apply a HIIT program for 4 weeks, with 3 sessions per week of 30 min per session, including warm-up, recovery between intervals and return to calm. | Other: High intensity interval training<br>* Participants will perform 3 HIIT sessions per week, involving 10 min of intense exercise within a time commitment of 30 min per session, including warm-up, recovery between intervals and cool down.<br>|
| Active Comparator: Inspiratory muscle training<br>It will apply an inspiratory muscle training for 4 weeks, with 3 sessions per week of 30 min per session, including warm-up, recovery between intervals and return to calm. | Other: Inspiratory muscle training<br>* Participants will perform 3 inspiratory resistance training sessions per week, involving 30 min per session, including warm-up, recovery between intervals<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Oxygen Saturation recovery | Oxygen Saturation recovery will be record by the experimenters every 5 seconds by a handheld pulse-oximeter during the 1 min recovery time after a maximal dynamic apnea. The outcome represents the time it takes to get a 95% of saturation during these 1 minute. | Before and after training intervention (after 4 weeks) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Lung function (forced spirometry) | The Spirometry will be perform according to American Thoracic Society criteria and was measured in litres. The maneuver will be perform 3 times and recording the best one. | Before and after training intervention (after 4 weeks) | 
| Maximum Respiratory Pressures | The maximum respiratory pressures (MIP and MEP) will be measure with a device. This device applies an inspiratory/expiratory load which provides a resistance. The maneuver will be perform in a sitting position. Measuring a minimum of 3 times will be perform, recording the highest value. | Before and after training intervention (after 4 weeks) | 
| Lactic acid recovery | The level of lactic acid in the blood will be measure by a device that used a blood lactic acid measurement that you've gotten by the finger-stick method. It will be record by the experimenters 3 times: immediately after the maximal dynamic apnea, after 3 min and after 10 min of the maximal dynamic apnea. | Before and after training intervention (after 4 weeks) | 
| Heart Rate recovery | Heart Rate will be record by the experimenters every 5 seconds by a handheld pulse-oximeter during the 1 min recovery time after a maximal dynamic apnea. The outcome represents how long does it take before the participant periodic Heart Rate is stabilized during these 1 minute. | Before and after training intervention (after 4 weeks) |