Aquatic High Intensity Interval Training for Cardiometabolic Health: Benefits and Training Design

Effects of aquatic high intensity interval training on parameters of functional autonomy, mental health, and oxidative dysfunction in elderly subjects with type 2 diabetes

The present study investigated the effects of aquatic exercise on parameters of functional autonomy, mental health, and oxidative dysfunction in elderly patients with DM2. A total of 130 elderly were included in the longitudinal clinical study and were attributed to the non-diabetic group (n = 27) and diabetes the group (n = 22). Both groups participated in 24 sessions of Hydro-HIIT, 48 h before and after Hydro-HIIT, the GDLAM index, depression, and anxiety scores and markers of oxidative dysfunction were quantified. After intervention, GI decreased in both groups (non-diabetes group = -24%; diabetes group = -22%) (p < 0.05), markers of depression (-46%), anxiety (-60%), DCFH-DA (-55%), SOD (+59%), TNF-α (-37%) and IL-1 (-48%) in diabetes group (p < 0.05). The intervention with Hydro-HIIT improves aspects related to functional autonomy, mental health, and exerts consequently, a modulating effect on oxidative stress and inflammatory response in elderly people diagnosed with DM2.

Aquatic high-intensity interval training (HIIT) may be similarly effective to land-based HIIT in improving exercise capacity in people with chronic conditions: a systematic review and meta-analysis

Objective

To investigate the effect of aquatic high-intensity interval training (AHIIT) on exercise capacity in people with chronic conditions.

Design

Systematic review and meta-analysis.

Participants

Adults (age ≥18 years) with any chronic conditions (long duration, continuing health problems).

Data sources

The databases Medline, EMBASE, CINAHL, SPORTSDiscus, PEDro and The Cochrane Library were searched from inception to 11 August 2023.

Eligibility criteria

Randomised or non-randomised controlled trials of adults reporting one or more chronic conditions were included, comparing the effect of AHIIT with a non-exercising control group, land-based high-intensity interval training (LBHIIT) or aquatic moderate-intensity continuous training (AMICT).

Results

Eighteen trials with 868 participants with chronic musculoskeletal, respiratory, cardiovascular, metabolic or neurological conditions were included. Adherence to AHIIT was high, ranging from 84% to 100%. There was moderate certainty in evidence according to the Grading of Recommendations Assessment, Development and Evaluation system for a moderate beneficial effect on exercise capacity standardised mean differences (SMD) 0.78 (95% CI 0.48 to 1.08), p<0.00001) of AHIIT compared with a non-exercising control group. There was moderate certainty in evidence for no difference of effects on exercise capacity (SMD 0.28 (95% CI -0.04 to 0.60), p=0.08) of AHIIT compared with LBHIIT. There was moderate certainty in evidence for small effect on exercise capacity (SMD 0.45 (95% CI 0.10 to 0.80), p=0.01) of AHIIT compared with AMICT.

Conclusion

There are beneficial effects of AHIIT on exercise capacity in people with a range of chronic conditions. AHIIT has similar effects on exercise capacity as LBHIIT and may represent an alternative for people unable to perform LBHIIT.

PROSPERO registration number

CRD42022289001.

The Effects of 6-Month Aqua Aerobics Training on Cardiometabolic Parameters in Perimenopausal Women-A Randomized Controlled Trial

BACKGROUND

Menopause is a time when women experience a number of physiological and anatomical changes resulting from a decline in ovarian function. It can be concluded that cardiovascular disease increases in perimenopausal and postmenopausal women, irrespective of age-related changes. Engaging in the amount of moderate physical activity recommended by the World Health Organization helps reduce the risk of death and adverse health events. The aim of the present study was to assess the effect of a 6-month aqua aerobics programme on cardiometabolic (anthropometric and biochemical) parameters in perimenopausal women.

METHODS

In this study, 30 women (control group-16, study group-14) participated in the 6-month aqua aerobics training programme. The mean age of women was 47.67 ± 6.79 year and BMI 26.33 ± 3.64 kg/m2. At the beginning and at the end of the study, anthropometric and blood samples analysis were performed. In the blood, lipid profile, morphotic elements were determined. Body composition, waist-hip ratio (WHR), visceral adiposity index (VAI), blood pressure (BP) were measured.

RESULTS

The aqua aerobics programme resulted in a significant decrease in the WHR (p < 0.05; ES: 2.143), diastolic blood pressure (DBP) (p < 0.05; ES: 1.005), and platelet-to-lymphocyte ratio (PRL) (p < 0.05; ES: 0.460) and an increase in haemoglobin (HGB) concentration (p < 0.05; ES: 0.643).

CONCLUSIONS

The type of physical activity described in the present study is a great way for perimenopausal women to take care of their overall well-being. The reduction in selected cardiometabolic parameters is important from the point of view of the protection of women's health.

Effects of Aquatic versus Land High-Intensity Interval Training on Acute Cardiometabolic and Perceptive Responses in Healthy Young Women

The effects of aquatic high-intensity interval training (AHIIT) on cardiometabolic and perceptive responses when compared to similar land-based exercise (LHIIT) remain unknown. Here, we aimed to (1) establish a matched intensity between mediums and (2) compare the acute cardiometabolic and perceptive responses to the two interventions in healthy young women. Twenty healthy young women performed a stationary running exercise at a matched exercise intensity. The incremental stages, in terms of percentage of heart rate (HR), maximal oxygen uptake (%VO₂max), percentage of oxygen uptake reserve (%VO₂R), percentage of heart rate reserve (%HRR), and rate of perceived exertion (RPE), were examined and acute cardiometabolic and perceptive responses were evaluated. The results showed that HR was significantly reduced (AHIIT: W 150 ± 19, R 140 ± 18, LHIIT: W 167 ± 16, R 158 ± 16 p < 0.01) and oxygen pulse (AHIIT: W 12 ± 2, R 10 ± 2, LHIIT: W 11 ± 2, R 9 ± 2 p < 0.05) was significantly increased with AHIIT compared to LHIIT. No significant group differences were observed for the perceptive responses. The comparable results demonstrated by the aquatic and land incremental tests allow precise AHIIT and LHIIT prescriptions. AHIIT had distinct differences in HR and oxygen pulse, despite having no distinct difference from LHIIT for some cardiometabolic and affective responses.

Effectiveness of Deep Water Running on Improving Cardiorespiratory Fitness, Physical Function and Quality of Life: A Systematic Review

Deep Water Running (DWR) is a form of aquatic aerobic exercise simulating the running patterns adopted on dry land. Little is known on the effectiveness of DWR despite gaining popularity. The objective of this study is to systematically review the effects of DWR on cardiorespiratory fitness, physical function, and quality of life in healthy and clinical populations. A systematic search was completed using six databases, including SPORTDiscus, MEDLINE, CINAHL, AMED, Embase, and The Cochrane Library, up to February 2022. Eleven studies evaluating the effectiveness of DWR on cardiorespiratory fitness (CRF), physical function, or quality of life (QoL), compared with no interventions (or standard treatment) or land-based trainings were identified. Data relevant to the review questions were extracted by two independent reviewers when means and standard deviations were reported, and standardized mean differences were calculated. A quality assessment was conducted using selected items from the Downs and Black checklist. A total of 11 clinical trials (7 randomized controlled trials) with a total of 287 participants were included. Meta-analyses were not completed due to the high level of clinical and statistical heterogeneity between studies. Compared with land-based training, DWR showed similar effects on CRF with limited studies reporting outcomes of physical function and QoL compared with the no-exercise control group. DWR appears to be comparable to land-based training for improving CRF. The aquatic environment may provide some advantages for off-loaded exercise at high intensity in populations that are weak, injured or in pain, but more studies are required.

Effects of aquatic high-intensity interval training and moderate-intensity continuous training on central hemodynamic parameters, endothelial function and aerobic fitness in inactive adults

Objective

The effects of land-based high-intensity interval training (HIIT) on the cardiovascular system have already been demonstrated. However, the water environment is different from that on land. Therefore, we investigated the effects of 6-week aquatic HIIT and moderate-intensity continuous training (MICT) on central hemodynamic parameters, endothelial function, and aerobic fitness in inactive adults.

Methods

Thirty-one inactive adults were randomly assigned to HIIT or MICT group. HIIT group performed twelve 30-s swimming exercise bouts with the intensity of 95% HR_max and 15-18/20 RPE with a 60-s rest period between each bout. MICT group performed a 30-min uninterrupted swimming exercise with the intensity of 70%-75% HR_max and 12-14/20 RPE. Training frequency for both groups was three times a week. The pulse wave analysis and flow-mediated dilation (FMD) were measured by non-invasive equipments.

Results

The aerobic fitness significantly increased after HIIT, but no change was seen after MICT. Augmentation pressure (AP) and augmentation index normalized at 75 bpm (AIx@HR75) significantly decreased after HIIT but not MICT, whereas MICT rather than HIIT improved subendocardial viability ratio (SEVR), central and peripheral blood pressure, and resting HR. Only HIIT significantly increased brachial endothelial function.

Conclusion

A six-week aquatic HIIT and MICT had no differences in hemodynamic parameters, endothelial function, and aerobic fitness, however 6 weeks of aquatic HIIT reduced arterial stiffness, increased endothelial function and aerobic fitness, while 6 weeks of aquatic MICT reduced arterial blood pressure and resting HR and increased the coronary blood flow reserve.

Effects of High-Intensity Aquatic or Bicycling Training in Athletes with Unilateral Patellofemoral Pain Syndrome

Patellofemoral pain syndrome (PFPS) is one of the most common overuse injuries experienced by athletes. It is characterized by pain and functional deficits that lead to decreased performance, thereby limiting sports activity. Therefore, optimal training interventions are required to improve physical fitness and function while minimizing pain due to PFPS. This study aimed to compare and analyze the effects of high-intensity aquatic training (AT) and bicycling training (BT) in male athletes with PFPS. Fifty-four athletes with PFPS were divided into AT and BT intervention groups. Intervention training was conducted three times per week for 8 weeks. Cardiorespiratory fitness was evaluated using the graded exercise test (GXT) based on peak oxygen uptake (VO₂ peak), and anaerobic threshold. For the knee strength test, extension and flexion were performed and measured using isokinetic equipment. One-leg hop tests and the Y-balance test (YBT) were performed to evaluate dynamic balance, and the International Knee Documentation Committee (IKDC) scoring system was used for subjective knee evaluation. The GXT, YBT, and IKDC scores were reported according to the group and duration of the intervention. After training, VO₂ peak, YBT, knee extension strength, and IKDC score improved significantly in both the AT and BT groups compared with the pre-training values. Furthermore, the AT group exhibited significant improvement compared with the BT group. We demonstrated that AT and BT effectively improved the symptoms and muscle strength of athletes with PFPS who were only able to engage in limited high-intensity field training. AT produced a modestly better effect than BT.

The effect of aquatic High Intensity Interval Training on cardiometabolic and physical health markers in women: A systematic review and meta-analysis

Background

We performed a meta-analysis of randomized controlled trials (RCTs) assessing the effect of Aquatic High Intensity Interval Training (AHIIT) on cardiometabolic and physical health markers in women.

Methods

Systematic search used 7 databases (MEDLINE, PubMed, SPORTDiscus, Cochrane, Embase, CINAL complete, PsycINFO). The Physiotherapy Evidence Database (PEDro) score was used to evaluate the methodological quality of the studies. Clinical trials compared AHIIT with a control group that receive no exercise training. We integrated randomized controlled trials published in English, and participants were women aged ≥18 years. The outcome of interest was the change in cardiometabolic and physical health markers.

Results

Among 242 articles screened, 18 articles (13 trials) were included in this meta-analysis comparing AHIIT (n = 261) with a control group (n = 215). The median PEDro score was 5.5 out of 10 (range, 4–8). AHIIT significantly improved peak oxygen uptake (Hedges' g 0.610; 95% CI 0.277–0.943; P < 0.001), reduced resting heart rate (Hedges' g −0.495; 95% CI -0.866 to −0.124; P < 0.05), as well as chair to stand test. (Hedges’ g 0.548; 95% CI 0.019 to 1.077; P < 0.05).

Conclusion

AHIIT has a moderate effect in improving cardiometabolic and physical health markers in women.

Accelerometer-based prediction of ground reaction force in head-out water exercise with different exercise intensity countermovement jump

Background

Water jumping exercise is an alternative method to achieve maintenance of bone health and reduce exercise injuries. Clarifying the ground reaction force (GRF) of moderate and high cardiopulmonary exercise intensities for jumping movements can help quantify the impact force during different exercise intensities. Accelerometers have been explored for measuring skeletal mechanical loading by estimating the GRFs. Predictive regression equations for GRF using ACC on land have already been developed and performed outside laboratory settings, whereas a predictive regression equation for GRF in water exercises is not yet established. The purpose of this study was to determine the best accelerometer wear-position for three exercise intensities and develop and validate the ground reaction force (GRF) prediction equation.

Methods

Twelve healthy women (23.6 ± 1.83 years, 158.2 ± 5.33 cm, 53.1 ± 7.50 kg) were recruited as participants. Triaxial accelerometers were affixed 3 cm above the medial malleolus of the tibia, fifth lumbar vertebra, and seventh cervical vertebra (C7). The countermovement jump (CMJ) cadence started at 80 beats/min and increased by 5 beats per 20 s to reach 50%, 65%, and 80% heart rate reserves, and then participants jumped five more times. One-way repeated analysis of variance was used to determine acceleration differences among wear-positions and exercise intensities. Pearson’s correlation was used to determine the correlation between the acceleration and GRF per body weight on land (GRF_VL_BW). Backward regression analysis was used to generate GRF_VL_BW prediction equations from full models with C7 acceleration (C7 ACC), age, percentage of water deep divided by body height (PWDH), and bodyweight as predictors. Paired t-test was used to determine GRF_VL_BW differences between values from the prediction equation and force plate measurement during validation. Lin’s CCC and Bland–Altman plots were used to determine the agreement between the predicted and force plate-measured GRF_VL_BW.

Results

The raw full profile data for the resultant acceleration showed that the acceleration curve of C7 was similar to that of GRFv. The predicted formula was − 1.712 + 0.658 * C7ACC + 0.016 * PWDH + 0.008 * age + 0.003*weight. Lin’s CCC score was 0.7453, with bias of 0.369%.

Conclusion

The resultant acceleration measured at C7 was identified as the valid estimated GRF_VL_BW during CMJ in water.

Comparing the Effects of Immersed Versus Land-Based High-Intensity Interval Cycling on Energy Intake, Appetite Sensations and Perceived Exertion Among Healthy Men

Immersed exercise has been shown to induce higher energy expenditure and no difference or increase in food intake compared with similar exercise on land. In this study, we compared the effects of acute high-intensity cycling performed on land versus when immersed on subsequent energy intake (EI), appetite sensations and perceived exertion (RPE) in healthy men. Ten participants in a postprandial condition completed three experimental visits in a randomized order: a control condition (CONT); a high-intensity interval cycling exercise performed on land (HIIE-L) and the same exercise while immersed in water (HIIE-A) with a similar targeted heart rate. We observed no difference in energy and macronutrient intake and in area under the curve (AUC) for appetite sensations between sessions. The RPE at the end of HIIE-L was negatively correlated with EI (r=-0.67; p < 0.05), AUC for hunger (r=-0.86, p < 0.01), desire to eat (r=-0.78, p < 0.05) and prospective food consumption (r=-0.86, p < 0.01). Conversely, the RPE at the end of HIIE-L was positively correlated with AUC for fullness (r = 0.76, p < 0.05). No such correlations were observed for HIIE-A. The present study was the first to observe that immersion did not influence EI after HIIE cycling, but immersion blunted the relationship between session RPE and subsequent energy intake and appetite sensations relative to HIIE on land.

Lower-Body Aquatic Training Prescription for Athletes

ABSTRACT

Holmberg, PM, Gorman, AD, Jenkins, DG, and Kelly, VG. Lower-body aquatic training prescription for athletes. J Strength Cond Res 35(3): 859-869, 2021-Traditionally prescribed to manage various medical ailments and promote healing, aquatic immersion may provide a favorable environment to undertake preparatory training tasks given its profound biological effects that extend across most homeostatic systems. In addition to understanding these effects, which are related to the fundamental principles of hydrodynamics, there is a need to consider the acute physiomechanical responses to alterations of key constraints associated with particular preparatory tasks. Evidence suggests that the manipulation of different constraints during aquatic training can enable a unique setting to complement, supplement, or supplant land-based programming to maintain or improve physical capacities in athletes without exacerbating physiological stress. Thus, this article focuses on the interplay of constraints and their associated outcomes to provide information that can be used to program lower-body aquatic training for athletes. In addition, the aim of the article is to summarize the literature on aquatic training to highlight the outcomes that occur when certain constraints are manipulated.

Changes in Inflammatory Cytokines and Irisin in Response to High Intensity Swimming in Adolescent versus Adult Male Swimmers

Swimming is a popular youth sport that is considered beneficial for cardiovascular fitness. However, the potential inflammatory outcomes of high intensity swimming in younger swimmers are unclear, as is the response of irisin, a myokine released during exercise with anti-inflammatory properties. This study compared the plasma concentrations of interleukins 1-beta (IL-1β), 6 (IL-6), 10 (IL-10), tumor necrosis factor alpha (TNF-α) and irisin in response to intense swimming between adolescent and adult male swimmers. Thirty-two swimmers (16 adolescents, 14 ± 1 years; 16 adults, 21.5 ± 3.1 years) completed a high intensity interval swimming trial. At rest, only TNF-α was higher (33%, p < 0.05) in adolescents compared with adults. There was an overall significant increase in IL-1β from pre- to post-swimming (3% in adolescents, 24% in adults), but no significant interaction. IL-10 significantly increased in both groups (+34% in adolescents, +56% in adults). IL-6 and TNF-α increased significantly (+32% and +26%, respectively) in adults, but not in adolescents (+2% and -9%, respectively). Adults showed a small, but significant decrease in irisin (-5%), with no change in adolescents. The lack of an IL-6, TNF-α and irisin response to intense swimming in adolescent swimmers may suggest a blunted inflammatory and myokine response following high intensity exercise in trained youth.

Head-Out Water-Based Protocols to Assess Cardiorespiratory Fitness-Systematic Review

The aquatic environment offers cardiorespiratory training and testing options particularly for individuals unable to adequately train or test on land because of weight bearing, pain or disability concerns. No systematic review exists describing cardiorespiratory fitness protocols used in an aquatic environment. This review investigated the different head-out water-based protocols used to assess cardiorespiratory fitness. Our comprehensive, systematic review included 41 studies with each included paper methodological quality assessed using the statistical review of general papers checklist. Diverse protocols arose with three major categories identified: conducted in shallow water, deep water, and using special equipment. Thirty-seven articles presented data for peak/maximal oxygen consumption (VO_2peak/VO_2max). Twenty-eight of 37 studies predefined criteria for reaching a valid VO_2peak/VO_2max with shallow water exercise demonstrating 20.6 to 57.2 mL/kg/min; deep water running 20.32 to 48.4 mL/kg/min; and underwater treadmill and cycling 28.64 to 62.2 mL/kg/min. No single, accepted head-out water-based protocol for evaluating cardiorespiratory fitness arose. For clinical use three cardiorespiratory fitness testing concepts ensued: water temperature of 28–30 °C with difference of maximum 1 °C between testing participants and/or testing sessions; water depth adapted for participant aquatic experiences and abilities; and intensity increment of 10–15 metronome beats per minute.

Aquatic high intensity interval training to improve aerobic capacity is feasible in adolescents with cerebral palsy: pilot randomised controlled trial

OBJECTIVE

To investigate feasibility of aquatic high intensity interval training for adolescents with cerebral palsy, who can ambulate independently but may choose a mobility aid in some circumstances.

DESIGN

Pilot randomised controlled trial.

METHOD

Following baseline assessments, participants were randomised to usual care or ten weeks of twice weekly aquatic high intensity interval training. Each class comprised 10 one-minute exercise intervals separated by one-minute rest. High intensity exercise was defined as the attainment of ⩾80% of peak heart rate measured by telemetry.

SETTING

Tertiary paediatric hospital.

MAIN MEASURES

Primary outcomes related to the feasibility of the protocol to progress to a definitive trial. Consumer feedback was obtained.

RESULTS

Of 119 potential participants, 46 appeared eligible and 17 consented, resulting in a recruitment fraction of 37% (95% CI 23-52). Twelve completed baseline assessments and were randomised (5 males; 14 years 7 months SD 2 years 0 months). In the intervention group, of the 1190 exercise stations (across all participants and sessions), heart rate data were available for 1180 stations and high intensity exercise was achieved during 1111 stations (93%, 95% CI 92-95). All randomised participants completed the study and reported that the intervention was fun and provided friendship opportunities. There were no major adverse events or exacerbation of pain.

CONCLUSIONS

Aquatic high intensity interval training in ambulant adolescents with cerebral palsy is feasible, while maintaining adherence and fidelity. Uncertainty remains on the efficacy of the intervention, highlighting the need for a large definitive trial.

Identification of Tools for the Functional and Subjective Assessment of Patients in an Aquatic Environment: A Systematic Review

Aquatic therapy is one of the most common treatments for alleviating musculoskeletal pathologies. Its effectiveness has been evaluated with functional tests and questionnaires. Functional tests are used in aquatic therapy; however, in most cases, they are carried out in a non-aquatic environment and, as such, their results may differ from those of tests performed in an aquatic environment. A systematic review was performed to assess the accuracy of functional tests and patient-reported outcomes to assess aquatic therapy interventions. The authors conducted a literature search in July 2019. In total, 70,863 records were identified after duplicates removed. Of these, 14 records were included about functional tests assessment in aquatic environment and 725 records for questionnaires. The majority of the tests had also been assessed in a dry environment, allowing differences and similarities between the tests in the two environments to be observed. Different variables have been assessed in tests included in the present systematic review (cardiorespiratory, neuromuscular, kinematic, physiological, kinetic responses and rating of perceived exertion) which are included in the manuscript. Visual Analogue Scale, Western Ontario and McMaster Universities Osteoarthritis Index and the 12-item Short Form Health Survey were the assessments most commonly used by the different authors.

Evaluation of Changes in Levels of Hyperandrogenism, Hirsutism and Menstrual Regulation After a Period of Aquatic High Intensity Interval Training in Women with Polycystic Ovary Syndrome

Background

Polycystic ovary syndrome (PCOS) is a polygenic endocrine disorder in women of reproductive ages which will lead to infertility. This study is aimed to determine changes in levels of hyperandrogenism, hirsutism and menstrual regulation after a period of aquatic high intensity interval training (AHIIT) in women with PCOS.

Methods

Thirty patients with PCOS having age between 20 and 35 and body mass index (BMI) ≥30 kg/m² in obstetrics and gynaecology clinics in Isfahan were selected based on Rotterdam Diagnostic Criteria. They were randomly divided into experimental (AHIIT + metformin, N = 15) and control groups (metformin, N = 15). The exercises were done for 12 weeks, three sessions of 20 minutes. Metformin (1500 mg) was taken daily for 3 consecutive days for 12 weeks. Kolmogorov-Smirnov test, t-test, Covariance and Wilcoxon were applied (P value < 0.05).

Results

After 12 weeks, no significant difference was observed in waist-to-hip ratio (WHR), but in AHIIT, the BMI and fat mass significantly decreased and levels of follicle-stimulating hormone (FSH), free testosterone (FT) and sex hormone binding globulin (SHBG) increased compared to control group (P < 0.05). While levels of improvement of total testosterone (TT), dehydroepiandrosterone sulphate (DHEAS), FT, luteinising hormone (LH) and free androgen index (FAI) were not significant between the two groups (P > 0.05). Furthermore, there was a significant decrease in homeostatic assessment of insulin resistance (HOMA-IR) and hirsutism severity in experimental group (P < 0.05). In both groups, the order of menstrual cycles improved significantly (P < 0.05).

Conclusions

Doing AHIIT besides drug therapy can be effective for PCOS patients.

The effect of aquatic high-intensity interval training on aerobic performance, strength and body composition in a non-athletic population: systematic review and meta-analysis

Objective:

In a non-athletic population, to (1) investigate the effectiveness of high-intensity interval training in an aquatic environment (A-HIIT) on aerobic performance, strength, and body composition and (2) report on safety of this approach.

Method:

A systematic search was undertaken of six databases until May 2018. Trials were eligible for inclusion if they compared the effect of A-HIIT in a non-athletic population with a control group that received no exercise training. Data were extracted independently by two reviewers and meta-analyses were undertaken using a random effects model to produce standardized mean difference (SMD) and 95% confidence intervals (CIs). Risk of bias was assessed using Cochrane’s risk of bias tool. All studies were graded using Physiotherapy Evidence Database (PEDro) and Consensus for Exercise Reporting Template (CERT) scales to determine quality of reporting.

Results:

Eight studies reported over 13 papers met study criteria ( n = 377). Compared with a control group, those who completed a program of A-HIIT demonstrated greater aerobic performance (SMD 0.69 (95% CI 0.39–0.98); I2 = 0%; n = 191) and lower limb muscle strength (SMD 0.30 (95% CI 0.04–0.56); I2 = 0%; n = 237). No differences were seen in measures of body composition or the number of adverse events. All studies were at risk of performance bias. The (mean ± SD) PEDro and CERT scores were 4.9 ± 1.5 and 15.1 ± 2.1, respectively.

Conclusion:

In a non-athletic population, A-HIIT was safe and may have improved aerobic performance and lower limb strength. The exercise interventions were well described and monitoring and reporting of exercise intensity in water was feasible.