The Galway Sea Swimmers Study

Study Overview
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Brief Summary
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Cardiovascular disease (CVD) is the leading cause of death worldwide. Hypertension is a well-established risk factor for the development of CVD. Lifestyle modifications, including exercise, remain the cornerstone of blood pressure (BP)-lowering strategy. Swimming has long been a popular recreational activity for exercise, and is recently gaining widespread recognition as an effective option in maintaining and improving cardiovascular health. Previous studies that involved pool swimming as an intervention (versus no pool swimming) demonstrated favorable benefits of the former on BP reduction. However, no studies to date have specifically investigated the effect of cold-water sea swimming on BP. Indeed, the naturally lower water temperature in the sea may engender a 'cold water immersion' experience in sea swimmers with subsequent stress physiology, which have been shown to exert unique effects on cardiovascular hemodynamics. This study primarily aims to determine the impact of cold-water sea swimming on BP in a group of habitual sea swimmers in Galway who will be randomly assigned to either continue or stop swimming for 4-6 weeks. Other objective and subjective health benefits to sea swimming will also be explored in this study. Given the ubiquitous nature of this activity in the Irish general public, particularly in Galway, this study has potential from a public health perspective, and would add to the literature base pertaining to the benefits of sea swimming on cardiovascular health.

Detailed Description
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Consenting participants will be randomly assigned, 1:1, to either continuation of sea swimming or discontinuation of sea swimming for 4-6 weeks, stratified by the type of swimmer (those who purely immerse in the water for a brief period of time versus those who actually swim [i.e., exercise] in the water) and use of blood pressure medication at the time of study commencement (yes or no), using a block size of four to maintain balance between intervention arms. In line with previous studies that assessed the impact of swimming intervention on BP, participants randomized to the swimming arm should pursue sea swimming 2 or more days/week.

Official Title
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The Galway Sea Swimmers Study: A Randomized Study of the Effect of Cold-Water Sea Swimming on Cardiovascular Risk Factors

Conditions
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Cardiovascular Diseases, Hypertension

Intervention / Treatment
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* Other: Cold-water sea swimming
* Other: No cold-water sea swimming


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: habitual swimmers (i.e., sea swimming at least 2 times/week for the past year) 18 years of age or older able to provide informed consent Exclusion Criteria: underlying cardiac (e.g., self-reported heart failure) or pulmonary diseases (e.g., self-reported chronic obstructive pulmonary disease) recent orthopedic procedures (e.g., joint replacement therapy) severe disabling comorbidity recent arm (both arms) or chest wall injury pregnant or breast feeding

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 100 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: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: No sea swimming<br>Stop sea swimming for 4-6 weeks | Other: No cold-water sea swimming<br>* Discontinue sea swimming for 4-6 weeks<br>|
| Active Comparator: Sea swimming<br>Continue sea swimming for 4-6 weeks | Other: Cold-water sea swimming<br>* Continue sea swimming for 4-6 weeks<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in mean systolic blood pressure | Systolic blood pressure recorded using a 24-hour ambulatory blood pressure monitor | Measured at baseline and again at 6 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Pulse Wave Velocity | Pulse wave velocity measured using Complior Device | Measured at baseline and 6 weeks | 
| Change in Augmentation index | Augmentation index measured using Complior device | Measured at baseline and 6 weeks | 
| Change in Heart rate variability | Measured using 24-hour ambulatory blood pressure monitor | Measured at baseline and 6 weeks | 
| Change in Health-related quality of life | Measure using EQ-VAS (visual analog scale) instrument. Values between 0 (worst imaginable health) and 100 (best imaginable health) | Administered at baseline and 6 weeks | 
| Change in mean diastolic blood pressure | Diastolic blood pressure recorded using a 24-hour ambulatory blood pressure monitor | Measured at baseline and again at 6 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Cardiovascular Diseases, Cardiac Disease, Heart Diseases, Hypertension, Blood Pressure, Swimming, Exercise, Vascular Stiffness, Pulse Wave Analysis, Health-Related Quality Of Life, Heart Rate Variability, Immersion