This research project aims to determine whether post exercise hot water immersion can improve vascular and cardiometabolic health to a greater extent than post exercise thermoneutral water immersion in healthy middle-aged adults. The study will take place over an 8 week period where participants will do a combination of aerobic exercise and water immersion 3 times per week. The study will be a randomised controlled trial comparing 8-weeks of post exercise hot water immersion (EX+HWI) to post exercise thermoneutral water immersion (EX+TNWI).
The exercise component of each intervention will be 30 minutes of moderate intensity aerobic exercise consisting of 10 minutes cycling, jogging and rowing, three times per week. Exercise intensity will be maintained at a heart rate equivalent of 65% of maximal heart rate. All exercise sessions will take the form of supervised group exercise sessions (\<4 participants) at Coventry University. After 30 minutes of exercise, participants will either complete 30 minutes of whole-body hot water immersion at 40°C or thermoneutral immersion at 34°C in the control condition (similar protocols are known to be well tolerated in older adults) (Akerman et al. 2019; Brunt et al. 2016). In order to ensure progression, exercise intensity will be increase to 75% of maximal heart rate according to the maximal exercise test at 4 weeks. Assessment sessions will take place before session 1 and \>48hrs after session 12 and 24. Prior to arriving at the lab participants will complete an overnight fast. Participants will also refrain from consuming alcoholic and caffeinated beverages, nitrate high sources and any form of strenuous exercise in the 24hr time period prior to testing. All testing laboratory visits will be completed in the morning and where possible at the same time of day to help standardise for any potential variations that the circadian rhythm may have on the measured variables. Assessments will be completed over two days. The outcome measures for this study comprise a range of physiological psychological measures which are known to inform the risk of cardiovascular disease. These measures fall into the following broad categories 1) vascular health; 2) cardiometabolic and inflammatory blood markers; 3) maximal exercise test and 4) cardiovascular disease risk prediction. In addition, measures of intervention acceptability and basic physiological heat acclimation measures will also be assessed.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
24
Light to moderate intensity aerobic exercise for 30 minutes, followed by 30 minutes of hot water immersion at 40°C.
Light to moderate intensity aerobic exercise for 30 minutes, followed by 30 minutes of thermoneutral water immersion at 34°C.
Coventry University
Coventry, West Midlands, United Kingdom
Change in resting systolic blood pressure (mmHg)
Measured using an automated blood pressure cuff
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in resting diastolic blood pressure (mmHg)
Measured using an automated blood pressure cuff
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in resting mean arterial blood pressure (mmHg)
Measured using an automated blood pressure cuff
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in flow mediated dilation (%)
Terason ultrasound recording after brachial artery occlusion
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in pulse wave velocity (ms-1)
SphygmoCor XCEL measuring carotid to femoral arterial stiffness
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in intima-media thickness (mm)
Terason ultrasound image to measure wall thickness from the lumen-intima interface to the media-adventitia interface of the brachial and femoral arteries
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in beta stifnness index
Calculated using systolic, diastolic blood pressure from automated blood pressure cuff and vessel diameter from Terason ultrasound image of brachial and femoral arteries
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in dynamic arterial compliance (mm2)
Calculated using pulse pressure from automated blood pressure cuff and vessel diameter from Terasol ultrasound image of brachial and femoral arteries
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in maximal oxygen uptake (ml/kg/min)
Maximal oxygen uptake
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in glucose tolerance (mmol/L)
Oral glucose tolerance test through fingertip capillary blood samples at 15 minute intervals for the first 1 hour and 30 minute intervals for the second hour
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating serum Interleukin-6 (pg/ml)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating serum TNF-α (pg/ml)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating serum Interleukin-8 (pg/ml)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating serum Interleukin-10 (pg/ml)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating serum Interleukin-1Ra (pg/ml)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating Endothelin-1 (pg/ml)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Circulating serum Monocyte chemoattractant protein-1 (pg/ml)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating serum Matrix metallopeptidase-2 (pg/ml)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating serum Matrix metallopeptidase-9 (pg/ml)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating total cholesterol (mmol/L)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating low density lipoproteins (mmol/L)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating high density lipoproteins (mmol/L)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating Triglycerides (mmol/L)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating glycated haemoglobin (%)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in circulating basal glucose (mmol/L)
Venous blood sample
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in Framingham risk score
Calculation based on age, gender, total cholesterol, HDL cholesterol, smoker, diabetes status and systolic blood pressure
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in rectal core temperature (°C)
Measured using a rectal probe attached to a squirrel data logger
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in resting heart rate (bpm)
Measured using a heart rate monitor
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Body mass index (kg/m²)
Calculated through height and weight
Time frame: Measurements taken the week before the study, >48hrs after 4 weeks and >48hrs after 8 weeks
Change in thermal comfort
Thermal comfort Likert scale from a positive score of +5 very comfortable (maximum) to a negative score of -5 very uncomfortable (minimum)
Time frame: Measurements taken pre and post visit 1, 12 (4 weeks) and 24 (8 weeks)
Change in thermal sensation
Thermal sensation Likert scale from a positive score of +5 hot (maximum) to a negative score of -5 cold (minimum)
Time frame: Measurements taken pre and post visit 1, 12 (4 weeks) and 24 (8 weeks)
Change in basic affect
Basic affect Likert scale from a positive score of +5 very good (maximum) to a negative score of -5 very bad (minimum)
Time frame: Measurements taken pre and post visit 1, 12 (4 weeks) and 24 (8 weeks)
Change in physical activity enjoyment
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Feelings about exercise and / or passive heating on a Likert scale from a positive score of 1 (maximum) to a negative score of 7 (minimum)
Time frame: Measurements taken pre and post visit 1, 12 (4 weeks) and 24 (8 weeks)