Regular swimming session improves metabolic syndrome risk factors in women and men from Palestine: Quasi-experimental study

Background: Swimming and other aquatic tness are important aerobic exercises that have been proposed as an effective nonpharmacological approach in the management of type 2 diabetes (T2DM), hyperlipidemia, and hypertension (HTN). The current study aimed to assess the effect of long-term swimming sessions on glycemic and lipidemic parameters, body composition, and hemodynamic responses for patients with metabolic risk factors. Methods: Forty participants from both genders with T2DM and HTN (aged 52.4±5.5 yrs) agreed to take part in this quasi-experimental study and were divided into two groups. The rst group included the participants who performed long-term swimming sessions and the second group served as the reference. The rst group exercised for 2 h, 3 times/week in 29-33 ◦ C swimming pool for 16 weeks. While the reference group did not participate in any kind of exercise and advised to keep on with their normal lifestyle. All the obtained metabolic syndrome risk factors data were analyzed using a paired t-test which was applied to separately determine the differences between pre- and post-tests for both genders and groups, and the percentage of change (Δ %) was computed. Independent t-test was applied to determine the differences in the post-tests (Exp. vs Ref) in men patients as well as for women separately. Results: The results showed that there were statistically signicant differences at p ≤ 0.05 between pre-and post- exercise concerning Total Cholesterol (TC), High-Density Lipoproteins (HDL), Low-Density Lipoproteins (LDL), Triglycerides (TG), glycemic parameters, systolic and diastolic blood pressures, body mass index (BMI) and fat mass percent in favor of posttests in the experimental group for both genders. Whereas, no signicant differences were found at p ≤ 0.05 between pre- and post-tests for all studied variables in the reference group for both genders. Signicant differences were found at p ≤ 0.05 on the post-tests in favor of the experimental for both genders. Conclusion: Findings of the current study suggested that the regular 16 weeks of the conducted

types of cardiovascular diseases. Moreover, various types of physical exercises have been found to slow aging, reduce physiological dysfunctions, and decrease the complications of DM by improving endurance, metabolism, muscle strength, circulation, and decreasing body fat mass (15,16). In addition, physically active individuals have higher insulin sensitivity, lower blood pressure, and a more favorable plasma lipoprotein pro le (17).
Moreover, the regular long term of different types of aerobic exercises has been shown to bene t many physiological and psychological disorders and diseases. Thus, can help in the treatment of obesity, overweight, reducing the risks of metabolic disorders, normalizing blood glucose and lipids pro les, helping with cancer-related side effects, and many other positive effects. While the endurance exercise on land has many adverse effects including gastrointestinal tract discomfort, burnout, eating disorders, and the risk of injury. While water exercises have fewer side effects such as dry skin, muscle spasm, and muscle pain (18)(19)(20).
Swimming is one of the safest and gratifying methods of aerobic physical exercise (21). In the regular form of swimming, people can burn a lot of calories, improve their skeletomuscular and other physiological functions with minimal negative effects on joints, heart, and other organs, especially in elderly people when swimming carried out at a moderate or low speed (22). Besides, moderate-intensity types of aerobic exercises, are promising lifestyle interventions to improve the cognitive function of patients with mild cognitive impairment who have a heightened risk of developing dementia (23). Moreover, regular aerobic exercises have a positive effect on improving symptoms of attention de cit hyperactivity disorder, anxiety, depression, and other mental health disorders (24,25).
Many of the scienti c data described the effects of swimming and other types of aerobic physical tness on diabetes, cardiovascular, and respiratory systems responses, also their effects on the serum lipid pro le, body fat percentage, muscle mass in subjects with T2DM (26)(27)(28)(29)(30).
To the best of our knowledge, investigations that describe the effects of long-term swimming sessions among patients suffering from T2DM and HTN as comorbid in Palestine are missing from the literature. Therefore, more information to evaluate the effects of regular long-term swimming procedures on glycemic and blood pressure parameters in T2DM and HTN patients is required.
Therefore, this study aims to investigate the outcomes of 16 weeks of swimming sessions on blood pressure levels, glycemic responses, lipid pro les, body mass index, and body fat percent in patients with T2DM and HTN compared with a reference group suffering from these disorders without swimming sessions.

Participants
Forty patients (twenty women and twenty men with age 52.35±5.5 yrs) who were diagnosed with T2DM and HTN from the employees of An-Najah National University were included in the current study. The study was conducted on a purposive sample consisting of two groups (experimental and reference( of 20 patients each. Both groups included patients of both genders evenly split between males and females. The men (n = 20) were divided equally into two groups, experimental and reference, as well as for women.
The rst group included the participants who performed long-term swimming sessions and the second group served as the reference. The reference group did not participate in any kind of exercises and advised to keep on with their normal lifestyle.
The experimental group underwent swimming as a recreational and sports program. The intensity of the swimming was moderate and below average and did not require high efforts such as walking in the water like free swimming for short distances also without looking at speed like standing in the water like swimming using rafts and ns. While in the reference group, they did not participate in any sports program throughout conducting this study and all the participants in the current study are persons who are athletically inactive and have normal skill level in swimming.
The study participants were instructed not to change their medications, diet, water intake, behavior, and sleep-rest patterns. Patients were also asked not to perform any other type of physical exercise during this experiment. T2DM and HTN medications had to be stable during the swimming sessions for all the participants.
Patients with a history of chronic pulmonary, stroke, and peripheral artery diseases also participants suffering from nephropathy, infections, peripheral ulcers, or problems with glycemic control were excluded from the current study. The participants were assigned for a 120 min swimming session, three times weekly for 16 weeks in the pool temperature of 29 to 33°C. Clari cation of the bene ts, possible risks and adverse effects of long-term swimming sessions of participating in this study were established before the participants signing the informed consent forms. The study complied with the Declaration of Helsinki. The Ethics committee of An-Najah National University approved the current study protocol under the archive number (3.7.2019). The biomedical tests were taken before starting the current study and repeated after sixteen weeks. The participants could stop the swimming sessions at any time they experienced the uncomfortable feeling.

Procedures
The instructions of swimming sessions were given to the participants during 16 weeks of this study by quali ed physical education researchers. Glucose levels were measured using a glucometer (OneTouch Ultra®, USA), while blood pressure was measured utilizing a mercury sphygmomanometer (Diamond BPMR120 Deluxe Conventional Mercurial Type BP Instrument, India). While the body mass index and fat mass percent were calculated by the researchers before and after nishing the current study. The serum glucose and blood pressure measurements were taken before and after 10 min of each swimming session. All participants provided the researchers with their biomedical laboratory analysis data, which were analyzed by a certi ed clinical laboratory for TG, TC, LDL, and HDL before starting and after nishing the current experiment.

Statistical Analyses
Means and standard deviations were utilized as descriptive statistics. A paired t-test was applied to determine separately the differences between pre-and post-tests for both genders and groups, and the percentage of change (Δ %) was computed. Independent t-test was applied to determine the differences in the post-tests (Exp. vs Ref) in men patients as well as for women separately. No abnormal distributions were noticed in pretests according to Shapiro-Wilk results for both genders and groups. In the men group as well as for women group, the experimental and reference groups were equivalent in pre-tests according to independent t-test results and no signi cant differences were found. The data were analyzed by Statistical Package for the Social Sciences (SPSS) version 20 (IBM SPSS® software, USA) program and the level of signi cance was xed at p ≤ 0.05.

Results
The results of paired t-test shown in Table 1. revealed that there were statistically signi cant differences at p ≤ 0.05 between pre-and post-tests of (TC, HDL, LDL, TG, glycemic parameters, systolic blood pressure, diastolic blood pressure, BMI, and fat) in favor of posttests in the experimental group for both genders. Whereas, no signi cant differences were found at p ≤ 0.05 between pre-and post-tests for all studied variables in the reference group for both genders as illustrated in Table 2.   Table 3. Which indicated that there were statistically signi cant differences at p ≤ 0.05 on all post-tests of (TC, HDL, LDL, TG, glycemic parameters, systolic blood pressure, diastolic blood pressure, BMI and fat) in favor of experimental group as illustrated in (Fig. 1). Concerning the comparison with the post-tests (Exp. vs Ref.) groups in women patients, the results of the independent t-test are shown in Table 4, which indicated that there were statistically signi cant differences at p ≤ 0.05 in the variables of (TC, HDL, LDL, TG, glycemic parameters, diastolic blood pressure, diastolic blood pressure, BMI and fat) in favor of experimental group as illustrated in (Fig. 2). No signi cant differences were found at p ≤ 0.05 for the systolic blood pressure variable.
Whereas, no signi cant differences were found at p ≤ 0.05 between pre-and post-tests for all studied variables in the reference group for both genders. Remarkably, these results emphasize that practicing regularly swimming patients have signi cant and positive effects on hyperlipidemia, T2DM, and HTN in comparison with who never participates in swimming sessions.
Vanhees et al. stated that engaging in regular physical exercise and exercise interventions including swimming, cycling, jogging, and walking, which, when carried out at moderate intensity are essential components for reducing the severity of cardiovascular risk factors, such as metabolic risk factors, systemic in ammation, high blood pressure, abdominal fat, and obesity (31). However, an investigation established by Prugger et al. showed that the lower frequency of regular exercise and decreased likelihood of exercise intention were observed in coronary heart disease patients with severe depression, while the symptoms of anxiety did not affect the regular exercise intention (32).
In a study conducted by Asa et al., 20 patients with both congestive heart failure and T2DM (age 67.4±7.1) were allocated randomly to either aquatic exercise or a control group. The patients exercised for 45 min 3 times per week in 33-34•C swimming pool temperature for 8 weeks. Hba1c decreased signi cantly (p ≤ 0.01) during training, while fasting glucose, insulin, c-peptide, and lipids were unchanged (26). In our opinion, Asa et al. study did not re ect the effect of swimming sessions on metabolic risk factors as in our study, as well as the mean age of the current study is different, also our conducted study was carried out for a 120 min each swimming session, 3 times weekly for 16 weeks. These factors positively affect the lipid and sugar metabolic markers' in our study in which decreased TC, LDL, TG, glucose levels signi cantly in swimming session men and women groups and increased the HDL levels. This nding is in agreement with the results of a study conducted by Kasprzak et al. on 32 obese women aged 41-72 yrs for three months and showed that all mean anthropometric variables were signi cantly lower (p ≤ 0.01). The blood lipid pro le, total cholesterol, and LDL-cholesterol were signi cantly lower (p ≤ 0.01). Furthermore, the levels of fasting TG, glucose, and insulin were decreased signi cantly (p ≤ 0.05) after nishing this study (28).
Moreover, in the current study, body mass index and body fat percent in the swimming session men group decreased signi cantly with Δ % of 8.15 and 17.99, respectively. While in women group decreased with the Δ % of 11.55 and 18.99, respectively. However, there were no signi cant changes in any of these variables in the current study reference group both genders.
However, the study by Gappmaier et al. on 38 middle-aged obese women (25-47% body fat) participated in a 13 weeks program aimed to compare the effects of aerobic water exercise vs walking on land and their results revealed also a signi cant reduction in body fat percent (3.7%), body weight (5.9 kg), skinfold and girth measurements, occurred in all groups. There were no signi cant differences between all the investigated groups as long as similar intensity, duration, and frequency are used (27).
The current study results revealed that the systolic blood pressure of the men patients in the experimental group fell signi cantly (p ≤ 0.05) from 151±10.61 to 125±8.36 mmHg, while the diastolic blood pressure changed signi cantly (p ≤ 0.05) from 99.60±4.81 to 87.60± 5.64 mmHg. There was a little change in any of these variables in the reference men group (Δ %=0.57) and (Δ %=2.14), respectively. Moreover, in the women experimental group, the results showed that systolic blood pressure fell signi cantly (p ≤ 0.05) from 164.90±10.64 to 143.20± 11.73 mmHg (Δ %=13.15), while the diastolic blood pressure changes signi cantly (p ≤ 0.05) from 97.70±2.66 to 87.50±4.32 mmHg (Δ %=9.92). There was a little change in any of the systolic and diastolic blood pressure variables in the reference women group (Δ %=4.11) and (Δ %=1.59), respectively.
Hirofumi et al. conducted a study on eighteen patients with HTN from both genders [aged 48±2 yrs) for 10 weeks using a swimming training program and the outcomes from this study showed that the systolic blood pressure of patients fell signi cantly (p ≤ 0.05) from 150±5 to 144±4 mmHg, while the diastolic blood pressure did not change signi cantly. There were no signi cant changes in any of these variables in the control group (33).
Predominantly, recreational swimming exercise is based on aerobic metabolism because both lipids and carbohydrates are involved as the major sources of energy. For that, aerobic exercises have a positive effect on the metabolism of these substances (28). Besides, several published studies demonstrated the positive relationship between aerobic aquatic exercise and good physiological and psychological conditions. These studies showed that regular physical exercises can reduce musculoskeletal disorders, many chronic diseases, anxiety, insomnia, depression, stress, and many others (18,(34)(35)(36).
In the post-tests (post-interventions), the ndings revealed that the experimental groups for both genders were better than reference groups, and signi cant differences were found at (p ≤ 0.05(. These ndings indicated the importance of regularly following physical exercises and practicing swimming or any physical activity to positively prevent or treat hyperlipidemia, T2DM, and HTN. In a previous study conducted on 159 overweight men and women with mild-to-moderate dyslipidemia In another study, Nualnim et al. sought to determine the effect of swimming training on decreasing blood pressure and improving vascular function in men and women (60±2) yrs old. The subjects were assigned to swimming exercises (experimental group) and relaxation exercises (attention or control group) for 12 weeks of a swimming training program. The results revealed a signi cant decrease in systolic blood pressure (SBP) in the swimming group. Swimming produced a 21% increase in carotid artery compliance.
No signi cant changes were observed in the control group (38).
In the current study, the concentration of glucose in blood decreased signi cantly (p < 0.05) in the experimental groups and better than the control groups. These results emphasize that regular swimming contributes to increase the uptake of glucose into skeletal muscle and could activate some hormones like adiponectin. Punthakee et al. con rmed that the higher circulating of adiponectin is bene cial during exercise and favors the oxidation of fat and glucose uptake into muscles. In addition, the weight loss, the decrease in the percentage of fat, and blood pressure could be key elements of decreasing T2DM (39 peripheral ulcers, or have problems with glycemic control, which are more common in patients with the combination of T2DM and HTN, were excluded from the current study. Furthermore, the current study was planned to be carried out for four, eight, and twelve months. Unfortunately, due to the COVID-19 pandemic, which started in our country in May 2020, we stopped the current study to protect the participants and researchers from this lethal infectious disease. A future study required to test all the metabolic risk factor markers, maximal oxygen uptake (VO2), and heart rate monitoring parameters for a longer period with a larger sample size

Conclusions
Sixteen weeks of regular swimming sessions resulted in signi cant reductions (p ≤ 0.05) between preand post-tests in blood glucose levels, lipids pro les, BMI, body fat percentages, and the arterial blood pressure readings for individuals with T2DM and HTN. Whereas, no signi cant differences were found at p ≤ 0.05 between pre-and post-tests for all studied variables in the reference group for both genders.
Taken together, our data demonstrated that regular long-term swimming sessions ameliorated glucose, body mass index, body fat percentage, DBP and SBP, and lipid pro les in patients with T2DM and HTN. Therefore, this kind of exercise can be an effective and safe therapeutic tool for patients with T2DM, HTN, hyperlipidemia, obesity, and overweight. This is a clinically crucial nding since a continuous swimming program can be a highly recommended alternative to land-based exercises for individuals with HTN and T2DM. Besides, it can be useful for individuals with obesity, overweight, and hyperlipidemia.  Figure 1 Means of post-tests according to group variable in men patients.

Figure 2
Means of post-tests according to group variable in women patients.