Effects of heated water-based exercise on blood pressure: a systematic review

Systemic arterial hypertension is one of the main cardiovascular risk factors affecting several population. In this context, heated water-based exercise has emerged as a potential alternative to land- based physical exercise to reduce blood pressure (BP) in hypertensive patients.

Objective:

To systematically synthesize evidence for the lowering effects of heated water-based exercise on BP in a non-specific population.

Methods:

Scielo, Pubmed and Scopus electronic databases were searched for studies from 2005 to 2016, with the following descriptors in English: “blood pressure, exercise, immersion, blood pressure and hydrotherapy”. A total of 10,461 articles were found and, after applying the inclusion and exclusion criteria, 13 articles were selected and included in the final analysis. All included articles evaluated individuals from different populations and age groups, submitted to a heated water-based exercise session and/or program.

Results:

The results suggest that both an acute single session and chronic training period (12 to 24 weeks) of heated water-based exercise may reduce BP in different populations (normotensive, hypertensive, postmenopausal women, and heart transplant populations). The magnitude and duration of acute and chronic hypotensive effect of exercise ranged substantially, which was probably due to the variety of exercise frequency, duration and intensity, as well as due to the studied population.

Conclusion:

These results suggest that heated water-based exercise may promote acute and chronic hypotensive effects in different populations. However, there is no homogeneity in the protocols used, which may have led to the heterogeneity in magnitude and duration of BP reductions.

Keywords:
Blood Pressure; Exercise; Hydrotherapy; Hypertension; Immersion

First author (Country) / Design	Population assessed	HEx intervention	LEx intervention	Control intervention	Water temperature	BP and secondary outcomes assessment
Studies assessing acute response to HEx
Cunha et al. (Brazil) / cross-over ²⁸28. 28. Cunha RM, Arsa G, Neves EB, Lopes LC, Santana F, Noleto MV, et al. Water aerobics is followed by short- time and immediate systolic blood pressure reduction in overweight and obese hypertensive women. J Am Soc Hypertens. 2016;10(7):570-7.	18 overweight (mean age 54.4 ± 7.9 yrs.) and obese hypertensive women (mean age 56.4±6.6 yrs.) were randomly assigned to HEx and CON intervention.	The water aerobics exercise session consisted of a 45-minute training at the intensity of 70%-75% of maximum heart rate adjusted for the aquatic environment.	NR	Control intervention	Water temperature	BP and secondary outcomes assessment	The control group did not enter the pool and did not perform any exercise.	28.5 ºC	Systolic and diastolic BP was measured before, immediately after, and every 10 min up to 30 min after HEx and CON intervention, using a semiautomatic device (Omron 705-CP).
Castro et al. (Brazil) / cross-over ⁶6. Castro RE, Guimarães GV, Silva JM, Bocchi EA, Ciolac EG. Postexercise Hypotension after Heart Transplant: Water-versus Land-Based Exercise. Med Sci Sports Exerc. 2016;48(5):804-10.	18 heart transplant patients (12 male/6 female, mean age 45.7 ± 2.7 yrs.) were randomly assigned to HEx, LEx and CON.	30 min moderate-intensity (11-13 in the 6-20 RPE) aerobic exercise (walking inside the pool immersed up to the xiphoid process).	30 min moderate-intensity (11-13 in the 6-20 RPE) aerobic exercise (walking on a motorized treadmill).	30 min of resting quietly in the seated position.	30-32 ºC	Ambulatory BP (systolic and diastolic) was measured during 24h after HEx, LEx and CON intervention, using an automatic device (Dyna-Mapa ABP monitor).
Garzon et al. (Canada) / cross-over ²³23. Garzon M, Juneau M, Dupuy O, Nigam A, Bosquet L, Comtois A, et al. Cardiovascular and hemodynamic responses on dryland vs. immersed cycling. J Sci Med Sport. 2015;18(5):619-23.	20 healthy normotensive (18 male/2 female, mean age (32 ± 7 yrs.) were randomly assigned to HEx and LEx.	Pedaling immersed on immersible ergocycle (Hydrorider®)-(immersion to the chest level). External power output on immersible ergocycle was controlled by pedaling rate (rpm). Initial rpm was set at 40 rpm and was increased by 10 rpm until 70 rpm and thereafter by 5 rpm until exhaustion.	Pedaling on dryland ergocycle (Ergoline 800S; Bitz, Germany). Initial external power output of dryland ergocycle protocol was set at 25W and increased by 25W every minute until exhaustion.	NR	30 ºC	Central hemodynamic parameters were measured continuously during exercise and a 5-min recovery period using a sphygmomanometer (WelchAllyn, USA). Central hemodynamic was measured continuously at rest, during exercise and after exercise cessation using impedance cardiography.
Luza et al. (Brazil) / cross-over ²⁶26. Luza M, Siqueira LO, Paqualotti A, Reolão JBC, Schmidt R, Calegari L. Efeitos do repouso e do exercício no solo e na água em hipertensos e normotensos. Fisioter Pesqui. 2011;18(4):346-52.	8 sedentary normotensive (1 male/7 female, mean age 62 ± 3.7 yrs.) and 12 sedentary hypertensive (3 male/9 female, mean age 59 ± 2.6 yrs.) were randomly assigned to HEx, LEx and CON intervention.	Heating; aerobic exercises; fortification; And stretching and relaxation, lasting 45 minutes [moderate- intensity (83-85% of HRMAX)].	The exercise was performed in athletics track, where the subjects were instructed to walk for 45 minutes in the heart rate intensity measured at the intensity corresponding to the anaerobic threshold [moderate- intensity (83-85% of HRMAX)].	In the ground rest protocol, the participants remained sitting for 45 minutes. In the rest protocol in the water, participants were immersed for 45 minutes in the pool. (The immersion occurred up to shoulder height.)	30-32 ºC	Systolic and diastolic BP (standard mercury sphygmomanometer Sankey), and Heart Rate were measured before and after (30, 60 and 90 min) each intervention.
Pugh et al. (Australia) / cross-over ²⁷27. Pugh CJ, Sprung VS, Ono K, Spence AL, Thijssen DH, Carter HH, et al. The effect of water immersion during exercise on cerebral blood flow. Med Sci Sports Exerc. 2015;47(2):299-306.	15 recreationally active healthy normotensive (8 male/7 female, mean age 26 ± 4 yrs.) were randomly assigned to HEx and LEx intervention.	Once immersed in water, participants remained in the resting upright position for 5 min, which was followed by a 20- min bout of low- intensity exercise consisting of a repetitive stepping protocol (approximately 100 bpm). Upon completion of the exercise bout, participants remained in the resting upright position for a further 5 min, after which, the pumps were reversed to empty the tank-30 min low- intensity (HR = 100 bpm).	Participants remained in the upright standing position and avoided movement for 5 min. This was followed by a 20- min bout of low- intensity exercise consisting of a repetitive stepping protocol (approximately 100 bpm). Upon completion of the exercise bout, participants remained in the resting upright position for a further 5 min.	NR	30 ºC	Finometer PRO (Finapres Medical Systems, Amsterdam, the Netherlands) was used to monitor relative changes in mean BP, cardiac output, and stroke volume, before, during, and 20 min after HEx and LEx intervention.
Sosner et al. (Canada) / cross-over ²¹21. Sosner P, Gayda M, Dupuy O, Garzon M, Lemasson C, Gremeaux V, et al. Ambulatory blood pressure reduction following high-intensity interval exercise performed in water or dryland condition. J Am Soc Hypertens. 2016;10(5):420-8.	42 hypertensive adults (22 male/20 female, mean age 65 ± 7 yrs.) were randomly assigned to HEx, LEx and CON intervention.	30 min High- intensity interval exercise in up-to-the-chest immersed condition was performed on a mechanically- braked cycle ergometer (Hydrorider, DIESSE, San Lazzaro di Savena, Italia). Each exercise session was preceded by a 5-min warm-up consisting in pedaling at 40 rpm and followed by a 5-min passive recovery period in a sitting position that began immediately after exercise cessation.	Moderate- intensity continuous exercise in dry land were performed on a stationary bicycle ergometer -- 24- min at 50% peak power output.	NR	30 ºC	The 24h Ambulatory BP (Systolic and Diastolic) was measured with a brachial cuff-based oscillometric device Mobil-O-Graph PWA Monitor (I.E.M. GmbH, Stolberg, Germany)- The monitor was programmed to measure BP every 20 min during the overall 24h.
			High-intensity interval exercise in dry land were performed on a stationary bicycle ergometer-- two sets of 10-min with phases of 15-sec 100% peak power output interspersed by 15-sec of passive recovery.	NR	30 ºC	Arterial stiffness was automatically assessed, using the same oscillometric device Mobil-O-Graph PWA Monitor (I.E.M. GmbH, Stolberg, Germany), at rest with the patient in supine position in a quiet atmosphere for the first measurement, and every 20 min during the following 24h.
Studies assessing chronic adaptation to HEx
Arca et al. (Brazil) / Parallel ²⁹29. Arca EA, Martinelli B, Martin LC, Waisberg CB, Franco RJ. Aquatic exercise is as effective as dry land training to blood pressure reduction in postmenopausal hypertensive women. Physiother Res Int. 2014;19(2):93-8.	52 hypertensive women (mean age 64 ± 7 yrs.) randomly assigned to HEx (n = 19), LEx (n = 19) or CON (n = 14) groups.	50-minute sessions on a three-time per week basis during 12 weeks. The heart rate was maintained around 50% to 60% of heart rate reserve.	50-minute sessions on a three-time per week basis during 12 weeks. Dry land exercise was performed in stationary bikes. In the land dry exercise program, the heart rate was maintained around 50% to 60% of heart rate reserve.	Did not change his eating habits and remained withou practicing physical activity in the period	33-33.5 ºC	BP measurements were performed with a mercury sphygmomanometer Premium G-tech®, adequately calibrated. In every one of the 12 weeks of intervention in aquatic and land, BP and heart rate were measured before subjects begun exercising, so respectively before immersion in water or before they had a walk on land.
Colado et al. (Spain) / Parallel ³³33. Colado JC, Triplett NT, Tella V, Saucedo P, Abellán J. Effects of aquatic resistance training on health and fitness in postmenopausal women. Eur J Appl Physiol. 2009;106(1):113-22.	46 postmenopausal women randomly assigned to HEx (n = 15, mean age 54.7 ± 2 yrs.), LEx (n = 21, mean age 54 ± 2.8 yrs.) or CON (n = 10, mean age 52.9 ± 1.9 yrs.) groups.	Training was performed twice per week in the first 12 weeks and three times per week for weeks 13-24. The total duration of the training session ranged from 35 to 60 min depending on the phase of periodization of the training program.	Training was performed twice per week in the first 12 weeks and three times per week for weeks 13-24. The total duration of the training session ranged from 35 to 60 min depending on the phase of periodization of the training program.	Did not change his eating habits and remained without practicing physical activity in the period.	NR	BP were taken at the same physician’s office within 1 week prior to and after the physical pre and post-testing, respectively. A resting BP measurement was taken after 10 min of quiet sitting. The BP measurement was repeated in the same manner after 48 h to ensure reliability.
Farahani et al. (Iran)/ Parallel ³⁴34. Farahani AV, Mansournia MA, Asheri H, Fotouhi A, Yunesian M, Jamali M, et al. The effects of a 10-week water aerobic exercise on the resting blood pressure in patients with essential hypertension. Asian J Sports Med. 2010;1(3):159-67.	40 men with stage 1 or 2 essential hypertension were assigned to HEx (n=12, mean age 48.33 ± 10.74 yrs.) or CON (n = 28, mean age 46.96 ± 11.58 yrs.) groups.	Subjects in the intervention group participated in a supervised 10-week water aerobic training program of 55 min sessions, 3 days per week on alternate days. The exercise intensity was set at 60-65% of the maximal heart rate and increased gradually up to 70-75% during the program.	NR	The control group were not involved in any regular training program during this period.	31-32 °C	Blood pressures were measured using mercury sphygmomanometers (Richter, Germany). Blood pressure was measured at baseline and 48 hours after the last exercise session to avoid the acute effects of a single bout of exercise.
Guimarães et al. (Brazil) / Parallel ¹⁸18. Guimaraes GV, Cruz LGB, Fernandes-Silva MM, Dorea EL, Bocchi EA. Heated water-based exercise training reduces 24-hour ambulatory blood pressure levels in resistant hypertensive patients: a randomized controlled trial (HEx trial). Int J Cardiol. 2014;172(2):434-41.	32 patients with resistant hypertension (15 male/17 female, mean age 53.7 ± 6 yrs.) randomly assigned to HEx (n = 16, 8 male/8 female, mean age 55±5,9 yrs.) or CON (n = 16.6 male/10f emale, mean age 52.4 ± 5.9 yrs.) groups.	60 min of moderate-intensity (11-13 in the 6-20 RPE) aerobic (walking inside the pool immersed up to the xiphoid process) and callisthenic exercise (immersed up to the xiphoid process) performed 3 times a week.	NR	The control group was asked to maintain habitual activities.	32 ºC	Systolic and diastolic BP were measured before, and after 2 and 12 weeks of HEx and CON intervention, using a standard mercury sphygmomanometer. Ambulatory BP (systolic and diastolic) was measured during 24 h before, and after 2 and 12 weeks of HEx and CON intervention, using an automatic device (Spacelabs model).
Lambert et al. (USA) / Parallel ³⁰30. Lambert BS, Greene NP, Carradine AT, Joubert DP, Fluckey JD, Riechman SE, et al. Aquatic treadmill training reduces blood pressure reactivity to physical stress. Med Sci Sports Exerc. 2014;46(4):809-16.	60 normotensive subjects (30 male/30 female) randomly assigned to HEx (n = 36.19 male/17 female, mean age 41 ± 2 yrs.) or LEx (n = 24.11 male/13 female, mean age 42 ±2 yrs.) groups.	Exercise training included three sessions per week for 12 weeks with sessions progressively increasing from 250 kcal per session, 60% V˙ O₂max during the first week, to 500 kcal per session, 85% V˙ O₂max during weeks 6-12.	Exercise training included three sessions per week for 12 weeks with sessions progressively increasing from 250 kcal per session, 60% V˙ O₂max during the first week, to 500 kcal per session, 85% V˙ O₂max during weeks 6-12.	NR	33 ºC	BP measured before, at the end of each stage, and for 5 min after exercise testing. Serial BP measurements were obtained using standard sphygmomanometric procedures with subjects resting in the supine position during the last 30 s of each 3-min stage of the graded exercise stress tests and at 1, 3, and 5 min during recovery.
Silva et al. (Brazil) / Parallel ³¹31. Silva J, Geraldes A, Natali A, Pereira J, Vale R, Dantas E. Acute Effects of Swimming on the Arterial Pressure of Hypertensive Adults. Maced J Med Sci. 2009;2(4):330-4.	26 hypertensive subjects (11 male/15 female) randomly assigned to HEx (n = 13.4 male/9 female, mean age 38.40 ± 8.24 yrs.) or CON (n = 13.7 male/6 female, mean age 38.36 ± 8.96 yrs.) groups.	Regular swimming program consisting of three weekly fifty-minute sessions of training for 10 weeks. The initial sessions had an intensity of around 40% of HRmax.	NR	Did not change his eating habits and remained without practicing physical activity in the period.	27-28 ºC	BP was measured with a digital arterial pressure monitor (Omrom® HEM-741C model, Japan). The measurements were taken always at the same time of day. Before training, the subjects were at rest for at least 10 minutes prior to the measurement of BP. Soon after the training session, the subjects remained at rest again for about 10 minutes before measurement.
Silva et al. (Portugal) / Parallel ³²32. Silva JE, Teixeira AMB, Dantas EHM, Rama LMPL. Comportamento da pressão arterial em homens pré- hipertensos participantes em um programa regular de natação. Rev Bras Med Esporte. 2015;21(3):178-81.	36 pre-hypertensive men randomly assigned to HEx (n = 24, mean age 40.60 ± 9.36 yrs.) or CON (n = 12, mean age 40.57 ± 8.05 yrs.) groups.	A regular swimming program was conducted, with three weekly sessions of 45 minutes for 12 weeks. The initial sessions had an intensity of around 40% to 50% of HR max.	NR	Did not change his eating habits and remained without practicing physical activity in the period.	27-29 °C	BP was measured according to the recommendations of the ACSM hypertension diagnosis, and was measured using an oscillometric device (Omrom, model HEM-741C, Japan).

First Author, Year	Criteria PEDro
First Author, Year	Eligibility	Subjects were randomly allocated	Allocation was concealed	Similar groups	Blinding of all subjects	Blinding of all therapists	Blinding of all assessors	Key outcome in more than 85% of the subjects	Intention to treat	Between-group statistical comparison	Point measure	Total
Arca, 2013 ²⁹29. Arca EA, Martinelli B, Martin LC, Waisberg CB, Franco RJ. Aquatic exercise is as effective as dry land training to blood pressure reduction in postmenopausal hypertensive women. Physiother Res Int. 2014;19(2):93-8.	Y	Y	Y	Y	N	N	N	Y	Y	Y	Y	7/10
Castro, 2016 ⁶6. Castro RE, Guimarães GV, Silva JM, Bocchi EA, Ciolac EG. Postexercise Hypotension after Heart Transplant: Water-versus Land-Based Exercise. Med Sci Sports Exerc. 2016;48(5):804-10.	Y	Y	Y	Y	N	N	Y	Y	Y	Y	Y	8/10
Colado, 2009 ³³33. Colado JC, Triplett NT, Tella V, Saucedo P, Abellán J. Effects of aquatic resistance training on health and fitness in postmenopausal women. Eur J Appl Physiol. 2009;106(1):113-22.	Y	Y	Y	Y	Y	N	N	N	Y	Y	Y	7/10
Cunha, 2016 ²⁸28. 28. Cunha RM, Arsa G, Neves EB, Lopes LC, Santana F, Noleto MV, et al. Water aerobics is followed by short- time and immediate systolic blood pressure reduction in overweight and obese hypertensive women. J Am Soc Hypertens. 2016;10(7):570-7.	Y	Y	Y	Y	Y	N	N	N	Y	Y	Y	7/10
Farahani, 2010 ³⁴34. Farahani AV, Mansournia MA, Asheri H, Fotouhi A, Yunesian M, Jamali M, et al. The effects of a 10-week water aerobic exercise on the resting blood pressure in patients with essential hypertension. Asian J Sports Med. 2010;1(3):159-67.	Y	N	N	Y	N	N	N	N	Y	Y	Y	4/10
Guimarães, 2014 ¹⁸18. Guimaraes GV, Cruz LGB, Fernandes-Silva MM, Dorea EL, Bocchi EA. Heated water-based exercise training reduces 24-hour ambulatory blood pressure levels in resistant hypertensive patients: a randomized controlled trial (HEx trial). Int J Cardiol. 2014;172(2):434-41.	Y	Y	Y	Y	N	N	Y	N	Y	Y	Y	7/10
Garzon, 2014 ²³23. Garzon M, Juneau M, Dupuy O, Nigam A, Bosquet L, Comtois A, et al. Cardiovascular and hemodynamic responses on dryland vs. immersed cycling. J Sci Med Sport. 2015;18(5):619-23.	Y	Y	Y	N	N	N	N	Y	Y	Y	Y	6/10
Lambert, 2014 ³⁰30. Lambert BS, Greene NP, Carradine AT, Joubert DP, Fluckey JD, Riechman SE, et al. Aquatic treadmill training reduces blood pressure reactivity to physical stress. Med Sci Sports Exerc. 2014;46(4):809-16.	Y	Y	Y	Y	Y	N	Y	Y	Y	Y	Y	9/10
Luza, 2011 ²⁶26. Luza M, Siqueira LO, Paqualotti A, Reolão JBC, Schmidt R, Calegari L. Efeitos do repouso e do exercício no solo e na água em hipertensos e normotensos. Fisioter Pesqui. 2011;18(4):346-52.	Y	Y	N	Y	Y	N	N	N	Y	Y	Y	6/10
Pugh, 2014 ²⁷27. Pugh CJ, Sprung VS, Ono K, Spence AL, Thijssen DH, Carter HH, et al. The effect of water immersion during exercise on cerebral blood flow. Med Sci Sports Exerc. 2015;47(2):299-306.	Y	Y	N	N	N	N	N	N	N	Y	Y	3/10
Silva, 2009 ³¹31. Silva J, Geraldes A, Natali A, Pereira J, Vale R, Dantas E. Acute Effects of Swimming on the Arterial Pressure of Hypertensive Adults. Maced J Med Sci. 2009;2(4):330-4.	Y	Y	Y	N	N	N	N	N	Y	Y	Y	5/10
Silva, 2015 ³²32. Silva JE, Teixeira AMB, Dantas EHM, Rama LMPL. Comportamento da pressão arterial em homens pré- hipertensos participantes em um programa regular de natação. Rev Bras Med Esporte. 2015;21(3):178-81.	Y	Y	N	Y	N	N	N	Y	Y	Y	Y	6/10
Sosner, 2016 ²¹21. Sosner P, Gayda M, Dupuy O, Garzon M, Lemasson C, Gremeaux V, et al. Ambulatory blood pressure reduction following high-intensity interval exercise performed in water or dryland condition. J Am Soc Hypertens. 2016;10(5):420-8.	Y	Y	N	Y	N	Y	Y	Y	Y	Y	Y	8/10

Studies assessing the acute response to heated water- based exercise
Luza et al. ²⁶26. Luza M, Siqueira LO, Paqualotti A, Reolão JBC, Schmidt R, Calegari L. Efeitos do repouso e do exercício no solo e na água em hipertensos e normotensos. Fisioter Pesqui. 2011;18(4):346-52.	In the hypertensive group, the exercise protocol on the ground caused an average reduction of 16.5 ± 3.7 mmHg (P = 0.01) in SBP at 90 minutes post-exercise. In the normotensive group, the protocol of rest in the water caused an average reduction of 14 bpm (P < 0.01) in HR.	The volume of diuresis was increased when compared with the protocols accomplished on the ground (P < 0.01).	The results suggest that when a physical exercise lasts 45 minutes, at submaximal intensity, it causes reduction of SBP in hypertensive individuals.
Pugh et al. ²⁷27. Pugh CJ, Sprung VS, Ono K, Spence AL, Thijssen DH, Carter HH, et al. The effect of water immersion during exercise on cerebral blood flow. Med Sci Sports Exerc. 2015;47(2):299-306.⁾	The HEx and LEx bouts were closely matched for mean arterial BP in 106 mmHg (95% CI) vs 101 mmHg (95% CI), and heart rate (95 bpm (95% CI, 90-101) vs 96 bpm (95% CI, 91-102, P = 0.65).	The oxygen consumption was similar between the groups (13.3 mL.kg.min (95% CI, 12.2-14.6) vs 13.5 mL.kg. min (95% CI , 12.1-14.8), P = 0.89). Compared with land-based exercise, water-based exercise induced an increase in middle cerebral artery blood flow velocity 74 cm⁄s (95% confidence interval, 66-81) vs 67 cm⁄s (95% CI , P = 0.001), posterior cerebral artery blood flow velocity 47 cm⁄s (95% CI ) vs 43 cm⁄s (95% CI , P = 0.001), and partial pressure of expired CO₂ (P = 0.001).	Water based exercise induces greater increase in cerebral blood flow velocity than land-based exercise of matched intensity. The water immersion may enhance the recurrent episodic increases in cerebral blood flow and shear stress that occur during exercise and, subsequently, amplify cerebrovascular health benefits associated with exercise training.
Cunha et al. ²⁸28. 28. Cunha RM, Arsa G, Neves EB, Lopes LC, Santana F, Noleto MV, et al. Water aerobics is followed by short- time and immediate systolic blood pressure reduction in overweight and obese hypertensive women. J Am Soc Hypertens. 2016;10(7):570-7.⁾	Overall (n = 18), DBP did not change after the HEx and CON, and SBP decreased at 10 and 20 min post exercise compared to the CON. Among overweight women, SBP decreased at 10 and 20 minutes post exercise. In contrast, among obese women, SBP decreased only at 10 minutes post exercise. SBP variation was 2.68 mmHg in overweight and 2.4 mmHg in obese women.	NA	The HEx session leads to a reduction in SBP, but not in DBP, during 10 and 20 minutes post exercise recovery.
Castro et al. ⁶6. Castro RE, Guimarães GV, Silva JM, Bocchi EA, Ciolac EG. Postexercise Hypotension after Heart Transplant: Water-versus Land-Based Exercise. Med Sci Sports Exerc. 2016;48(5):804-10.	No significant differences between interventions were found in 24h and nighttime BP. However, daytime DBP was significantly lower after HEx than CON (-4 ± 1.6 mmHg, P = 0.03), and daytime DBP tended to be lower after LEx than CON (-2.3 ± 1.1 mmHg, P = 0.052). Hourly analysis showed that SBP and DBP values were lower after HEx (average reductions of 6.6 to 12.3 mmHg, P < 0.01) and LEx (average reductions of 5 to 8.3 mmHg, P < 0.05) than after CON in several hours. No significant differences between HEx and LEx were found in any ambulatory BP data.	NA	HEx and LEx promoted similar reductions in ambulatory BP of heart transplant recipients. This post exercise hypotension occurred even though the heart transplant recipient patients had lower control ambulatory BP levels (average 24h of 122/81 mmHg), which does not occur in non-heart transplant recipient populations. These results suggest that both exercises may be tools to counteract hypertension in this high-risk population.
Garzon et al. ²³23. Garzon M, Juneau M, Dupuy O, Nigam A, Bosquet L, Comtois A, et al. Cardiovascular and hemodynamic responses on dryland vs. immersed cycling. J Sci Med Sport. 2015;18(5):619-23.⁾	BP and systemic vascular resistance were not different in exercise on HEx and LEx in ergocycle. The stroke volume and cardiac output were significantly higher during exercise on immersible ergocycle (P < 0.05, g = 0.59 and 0.20 respectively). The stroke volume, ejection fraction and contractility index were higher (P < 0.05, g = 0.64, 0.71 and 0.19 respectively).	Both oxygen uptake and arteriovenous difference were significantly lower during exercise on immersible ergocycle (P < 0.001, g = −0.25 and −0.87 respectively). During recovery, oxygen uptake and arteriovenous difference were significantly reduced in water (P < 0.001, g = −0.41 and −0.67).	During exercise and recovery in immersion, arteriovenous differences were reduced in healthy young participants, while stroke volume and cardiac output were increased for the same external power output. During the recovery, central hemodynamic responses remained higher in immersible ergocycle. BP and systemic vascular resistance were not different between the two conditions.
Sosner et al. ²¹21. Sosner P, Gayda M, Dupuy O, Garzon M, Lemasson C, Gremeaux V, et al. Ambulatory blood pressure reduction following high-intensity interval exercise performed in water or dryland condition. J Am Soc Hypertens. 2016;10(5):420-8.	Dryland high intensity interval exercise induced a significant decrease in both SBP and DBP measures during the 24h period (SBP: -3.6 ± 5.7 mmHg, P = .04; DBP: -2.8 ± 3.0 mmHg, P = .00) and the daytime period (SBP: -4.4 ± 7.5 mmHg, P = .046; DBP: -2.9 ± 4.0 mmHg, P =.02) but not during the nighttime period. High intensity interval exercise immersed resulted in a greater decrease from baseline in systolic measures during the 24h period SBP: -6.8 ± 9.5 mmHg, P = .02) and the daytime period (SBP: -7.5 ± 11.2 mmHg, P = .03). There was also a decrease in diastolic measures during the 24h period (DBP: -3.0 ± 4.5 mmHg, P = .03) and the daytime period (DBP: -3.9 ± 4.5 mmHg, P = .006).	NA	In individuals with a baseline office BP ≥ 130/85 mmHg, the 24h BP load decreased significantly following a bout of high intensity interval exercise performed on a stationary cycle in immersed condition.
Studies assessing the chronic response to heated water-based exercise
Guimarães et al. ¹⁸18. Guimaraes GV, Cruz LGB, Fernandes-Silva MM, Dorea EL, Bocchi EA. Heated water-based exercise training reduces 24-hour ambulatory blood pressure levels in resistant hypertensive patients: a randomized controlled trial (HEx trial). Int J Cardiol. 2014;172(2):434-41.	12 weeks of HEx significantly decreased SBP and DBP in the 24-hour period (19.5 ± 11.0 and 11.1 ± 3.1 mmHg), daytime (22.3 ± 12.6 and 13.0 ± 3.6 mmHg) and nighttime (17.4 ± 9.1 and 8.5 ± 2.1 mmHg). SBP office was reduced from 162 to 144 mmHg (P < 0.004) after HEx. After Hex, during 24-h ambulatory BP, SBP decreased from 135 to 123 mmHg (P = 0.02), DBP decreased from 83 to 74 mmHg (P = 0.001), daytime SBP decreased from 141 to 125 mmHg (P = 0.02), DBP decreased from 87 to 77 mmHg (P = 0.009), night-time SBP decreased from 128 to 118 mmHg (P = 0.06) and DBP decreased from 77 to 69 mmHg (P = 0.01). In addition, BP cardiovascular load was reduced significantly during the 24-h daytime and night-time period after the HEx. HEx reduced office BP and 24-h daytime and night-time ambulatory BP levels.	NA	HEx induced beneficial effects on BP in patients with resistant hypertension, and there were no signs of adverse reactions. These effects suggest that HEx may have a potential as a new therapeutic approach to resistant hypertensive patients.
Arca et al. ²⁹29. Arca EA, Martinelli B, Martin LC, Waisberg CB, Franco RJ. Aquatic exercise is as effective as dry land training to blood pressure reduction in postmenopausal hypertensive women. Physiother Res Int. 2014;19(2):93-8.	Reduction on SBP in water group from 136 ± 16 mmHg at week zero to 124 ± 15 mmHg at week 12. In LEx, there was a reduction from 138 ± 15 mmHg at week zero to 126 ± 9 mmHg at week 12. SBP has no changes in CON.	NA	The lowering of BP in hypertensive women submitted to HEx was similar to the one obtained with LEx and more intense than in the inactive CON. This controlled study addresses the antihypertensive effect of HEx in post-menopausal women.
Lambert et al. ³⁰30. Lambert BS, Greene NP, Carradine AT, Joubert DP, Fluckey JD, Riechman SE, et al. Aquatic treadmill training reduces blood pressure reactivity to physical stress. Med Sci Sports Exerc. 2014;46(4):809-16.	HEx decreased resting DBP (-3.2 mmHg, P< 0.05) significantly when compared to LEx, SBP (-9.0 to 18.2 mmHg, P < 0.05), mean arterial pressure (-4.8 to 8.3 mmHg, P < 0.05), pulse pressure (-7.5 to 15 mmHg, P < 0.05), and rate pressure product (-1.8 to 3.9 bpm.mmHg.103, P < 0.05). Under exercise stress, HEx, but not LEx, demonstrated reductions in HR (range 6.5-7.9 bpm lower for each stage, P < 0.05).	NA	The HEx preferentially ameliorates blood pressure reactivity to exercise stress, which would then be predicted to prevent or delay the onset of chronic diseases such as essential hypertension.
Silva et al. ³²32. Silva JE, Teixeira AMB, Dantas EHM, Rama LMPL. Comportamento da pressão arterial em homens pré- hipertensos participantes em um programa regular de natação. Rev Bras Med Esporte. 2015;21(3):178-81.	The SBP and DBP significantly reduced only in HEx (5.89 mmHg for SBP and 5.15mmHg for DBP).	NA	The results show that regular HEx causes significant decreases in systolic and diastolic pressures in prehypertensive men.
Silva et al. ³¹31. Silva J, Geraldes A, Natali A, Pereira J, Vale R, Dantas E. Acute Effects of Swimming on the Arterial Pressure of Hypertensive Adults. Maced J Med Sci. 2009;2(4):330-4.	Comparisons of the BP levels observed before and after the intervention revealed no statistically significant differences.	NA	Despite evidence demonstrating the benefits of swimming for arterial pressure, it is necessary to emphasize the need for further studies to determine the optimal parameters for the prescription of physical activity for hypertensive individuals. Thus, the activities or forms of exercise can be selected to meet the personal characteristics of each individual in order to enhance the prevention, treatment, and control of hypertension.
Colado et al. ³³33. Colado JC, Triplett NT, Tella V, Saucedo P, Abellán J. Effects of aquatic resistance training on health and fitness in postmenopausal women. Eur J Appl Physiol. 2009;106(1):113-22.⁾	The DBP significantly reduced (P ≤ 0.01) in both exercise groups (6.8 mmHg in HEx group and 4.8 mmHg in the elastic band group).	NA	Training with aquatic resistance exercises is a viable alternative to traditional resistance with elastic bands, and may provide more benefits to individuals who would be more sensitive to heavier loads or to impact, which may occur when training on LEx with certain devices and exercises.
Farahani et al. ³⁴34. Farahani AV, Mansournia MA, Asheri H, Fotouhi A, Yunesian M, Jamali M, et al. The effects of a 10-week water aerobic exercise on the resting blood pressure in patients with essential hypertension. Asian J Sports Med. 2010;1(3):159-67.	Exercise lowered SBP and mean arterial pressure by 11.71 (95% confidence interval: 5.07 to 18.35) and 5.90 (95% confidence interval: 1.17 to 10.63) mmHg respectively. The lowering effect of exercise on DBP was neither statistically significant nor clinically important (0.55 mmHg; P = 0.8).	There was no significant effect of age, baseline body mass index and stage of hypertension on the exercise-induced changes in BP.	A 10-week course of HEx markedly reduced the systolic and mean arterial BP of patients with essential hypertension and is especially recommended for the obese and the elderly who have orthopedic problems or bronchospasm.

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[1] * Master’s student, e-mail: awassiyn@gmail.com