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64 Journal of Exercise Physiologyonline Volume 15 Number 2 April 2012 Editor-in-Chief JEPonline Tommy Boone, PhD, MBA Review Board Todd Astorino, PhD Twelve Weeks of Aqua-Aerobic Exercise Improve Julien Baker, PhD Physiological Adaptations and Glycemic Control in Steve Brock, PhD Elderly Patients with Type 2 Diabetes Lance Dalleck, PhD Eric Goulet, PhD Robert Gotshall, PhD Apiwan Nuttamonwarakul1, S. Amatyakul2, D. Suksom3 Alexander Hutchison, PhD 1 M. Knight-Maloney, PhD Inter-department of Biomedical Sciences, Chulalongkorn University, Len Kravitz, PhD Bangkok, Thailand, 2Department of Physiology, Faculty of Dentistry, James Laskin, PhD Chulalongkorn University, Bangkok, Thailand, 3Faculty of Sports Yit Aun Lim, PhD Lonnie Lowery, PhD Science, Chulalongkorn University, Bangkok, Thailand Derek Marks, PhD Cristine Mermier, PhD ABSTRACT Robert Robergs, PhD Chantal Vella, PhD Nuttamonwarakul A, Amatyakul S, Suksom D. Twelve Weeks of Dale Wagner, PhD Frank Wyatt, PhD Aqua-Aerobic Exercise Improve Physiological Adaptations and Ben Zhou, PhD Glycemic Control in Elderly Patients with Type 2 Diabetes. JEPonline 2012;15(2):64-70. Aqua-aerobic exercise (AE) has been proposed as an alternative mode of exercise in the medical management of type 2 Official Research Journal of diabetic (T2DM) patients. The purpose of this study was to investigate the American Society of Official Research Journal Exercise Physiologists the effects of a 12-wk AE training program on physiological of the American Society of adaptations and glycemic control in older subjects with T2DM. Forty Exercise Physiologists ISSN 1097-9751 elderly subjects with diagnosis of T2DM were assigned either to the AE group (n=20) or the non-exercise control group (n=20). The AE ISSN 1097-9751 group performed aerobic exercise in the swimming pool (water temp ~34 to 36°C), which consisted of 3 days/wk at 70% of maximum heart rate for 30 min. The aqua-aerobic training group demonstrated a significant increase in VO2 max, and a significant reduction in body weight, percentage of body fat, blood pressure, and resting heart rate at the 12th week of training (P<0.05). Glycosylated hemoglobin (HbA1c), cholesterol, triglyceride, and insulin decreased significantly (all P<0.05) in the AE group compared to the non-exercise control group. These findings indicate that 12 wks of AE training may help prevent complications in elderly patients with T2DM. Key Words: Water-Based Training, Hyperglycemia, Ageing, Fitness 65 INTRODUCTION Type 2 diabetes mellitus (T2DM) is expected to increase by 46% around the world, and the incidence of T2DM is increasing rapidly as a result of the ageing population. It is one of the fastest growing public health problems, which is associated with numerous complications (e.g., retinopathy, nephropathy, and atherosclerotic heart disease) that result from prolonged hyperglycemia (10). Aquatic exercise has been found to slow the age-associated physiological declines and decrease the risk for T2DM by improving the circulation, muscle strength, and endurance (12,16). Scientific reports are also available on the renal-endocrine response during water immersion at rest and during water- based exercise in older adults (14,15). Aquatic exercise training improves glucose uptake by lowering both insulin resistance and body fat in subjects with T2DM. However, there are only a few reports that describe the long-term effects of aquatic exercise in older adults. In particular, more information is needed in regards to the effects of a regular aquatic exercise program on physiological adaptations and glycemic control in the elderly T2DM subjects. The purpose of this study was to investigate the effects of 12-wks aqua-aerobic exercise training on the physiological adaptations and glycemic responses in elderly subjects with T2DM. METHODS Subjects Forty subjects with T2DM (who were over 60 yrs of age) were recruited from the Ageing Center of the local community, Thailand. The subjects were randomly divided into the aquatic exercise group (AE; n=20) and the non-exercise control group (NC; n=20) group in a 12-wks program. All subjects were medically screened before participation and no medications were altered during the exercise training period. The experimental protocol was approved by the supreme patriarch center on aging research and ethics committee, Ministry of Public Health. Explanation on experimental procedures, possible risks and benefits of participating in the study were done prior to the subjects’ signing the informed consent form. Procedures The AE group participated in a 12-wk aquatic exercise program 3 day·wk-1 for 50 min per day with an average water temperature of ~34 to 36°C. Each session was led by one of the researchers. Prior to each exercise class, the subjects were asked to avoid vigorous physical activity, caffeine, and alcoholic beverages. They were also asked to eat regular meals with an appropriate amount of water and sleep-rest period. The AE program consisted of 10 min of stretching and warm-up exercises followed by 30 min of aquatic exercise at 70% of maximum heart rate (HR) and, then, cool-down exercises for 10 min. The HR was monitored continuously for all subjects during the training sessions by a HR monitoring device (Polar team 2pro, Finland) to ensure that the training intensity was maintained as prescribed. The subjects were asked to report abnormal signs and symptoms, and understood that at any time they experienced uncomfortable feeling they could stop exercising. Subjective estimation of working load was carried out using rating of perceived exertion (RPE) scale. All parameters were assessed before and after the 12-wk aquatic exercise training. Resting HR and blood pressure were taken after 10 min of quiet sitting. Body weight, height, and percentage of body fat were also measured. Body composition was measured by the bioelectrical impedance method (RJL System, Detroit, MI, USA). Maximal oxygen uptake (VO2 max) was determined using a gas analyzer (Cosmed, Rome, Italy) with the modified Bruce treadmill (Quinton, USA) protocol. Perceived exertion was rated every minute 66 using the Borg scale. The attainment of VO2 max was validated if two of the following four criteria were satisfied: (1) oxygen uptake plateau despite increasing exercise intensity (≤120 mL·min-1); (2) respiratory exchange ratio ≥1.15; (3) maximal heart rate within 10 beats·min-1 of the age-predicted maximal value; and (4) a Borg scale value ≥17. Venous blood was drawn after an 8-hr overnight fast. The resulting serum was immediately analyzed by a certificated clinical laboratory for glycosylated hemoglobin (HbA1c), cholesterol, triglyceride, and insulin. Statistical Analyses All values were presented as means ± SD. The differences of various parameters between pre- and post-test exercise training were analyzed by paired t-test. Student’s t-test was used for comparing data between groups. The P value, set a priori, of <0.05 was considered statistically significant. RESULTS Physiological Data After the 12 wks, only the AE group showed a significant decrease (P<0.05) in body weight, percentage body fat, systolic blood pressure, diastolic blood pressure, and resting HR. Maximum oxygen consumption (VO2 max) was significantly increased from baseline (P<0.05) in only the AE group (Table 1). Table 1. Physiological Adaptations after 12 wks of Training. Aquatic Exercise Group Control Group Variables (n=20) (n=20) Baseline After 12 wks Baseline After 12 wks Body weight 62.88.6 61.18.3* 61.110.6 61.410.7 (kg) Body fat 39.45.5 38.55.8* 36.54.9 37.15.0 (%) SBP 117.615.0 115.213.4* 114.29.5 114.512.2 (mm Hg) DBP 74.711.6 71.78.3* 70.76.8 73.46.0 (mm Hg) HR rest 82.311.3 73.37.8*,** 78.67.9 80.77.2** (beats·min-1) VO2max 24.92.8 25.12.0* 24.52.7 24.12.3 -1 -1 (mL·kg ·min ) Values are mean SD. SBP; Systolic Blood Pressure, DBP; Diastolic Blood Pressure, HR; Heart rate, VO2 max; Maximal oxygen uptake. *represents statistical difference from pretest at P<0.05 and **represents statistical difference between groups at P<0.05. 67 Blood Chemistry Parameters Glycosylated hemoglobin (HbA1c), cholesterol, triglyceride, and insulin were significantly decreased (P<0.05) only in the AE group. There were no significant changes in these variables in the NC group (Table 2). Table 2. Changes in Blood Chemistry Parameters after 12 wks of Training. Aquatic Exercise Group Control Group Variables (n=20) (n=20) Baseline After 12 wks Baseline After 12 wks HbA1c 7.71.1 6.60.7*,** 7.60.2 7.60.3** (%) Cholesterol 231.630.0 221.029.6* 232.150.0 231.349.3 (mg/dL) Triglyceride 178.782.3 161.973.9* 177.160.1 176.259.1 (mg/dL) Insulin 23.64.1 22.53.4* 22.15.1 22.55.3 (µU/mL) Values are mean SD. FBG; Fasting blood glucose, HbA1c; glycosylated hemoglobin. *represents statistical difference from pretest at P<0.05 and **represents statistical difference between groups at P<0.05. DISCUSSION Twelve weeks of aqua-aerobic exercise (AE) training significantly improved in the physiological adaptations and glycemic control in subjects older than 60 yrs of age by reducing weight, percentage body fat, blood pressure, and increasing VO2 max. Also, there were improvements in HbA1c, cholesterol, triglyceride, and insulin. These results are supported by previous reports (4,6,17) that concluded deep water running is effective in maintaining and improving cardiovascular fitness (as well as resistance-type shallow water exercise improving strength and functional mobility). In the present study, the AE group showed a significant difference in HbA1c when compared to the control group. It is clear that the AE training protocol was sufficient to improve the physiological status of older subjects with T2DM. The decreases in body weight and percentage of body fat after 12 wks of aquatic exercise training are favorable changes in subjects with T2DM. The effects of exercise training in water on body composition have been controversial in several studies. Some investigations did not detect significant change after aquatic training while others reported a reduction in body fat (3). This may be due to the different methods used to assess body composition and/or different training regimens (i.e., aerobic training vs. resistance training). Low cardiorespiratory fitness (as defined by VO2 max) is prevalent among individuals at high risk for T2DM. Therefore, a significant increase in VO2 max (i.e., even a small increase) at 12 wks of AE training should be viewed as a positive physiological response (in terms of cardiovascular disease). Clearly, exercise programs for diabetic patients should consist of a 5 to 10 min warm-up and cool- 68 down to improve cardiovascular performance. Then, the recommended frequency of exercise is should be between 3 to 5 sessions per week with at least 30 min of continuous and moderate exercise in each training session (1,2). The incremental speed of underwater movements in the present study improved physiological adaptation and cardiovascular responses, which are consistent with the findings of earlier studies. Changes in resting heart rate and blood pressure (systolic and diastolic blood pressures) at 12 wks of training in the AE group were also found. Aqua-aerobic exercise training, when properly supervised, is an excellent type of exercise to improve the hemodynamic responses of T2DM subjects. This was demonstrated with the decrease in the subjects’ HR and the improvement in the sensitivity of the aortic baroreceptors, which contributed to a more efficient regulation of blood pressure (7,9,11). Moreover, the hydrostatic pressure of being in the water helped to increase the venous return to the heart and, thus improve the subjects’ blood circulation (8). Changes in glycemic control that resulted from the 12-wk aqua-aerobic exercise training are indicated in the significant decreases in HbA1c, cholesterol, triglyceride, and insulin. Aquatic exercise improved the subjects’ glycemic control, which has been reported in a randomized controlled trial in 251 T2DM patients. The authors reported improvements ranging from -0.38 to -0.97 percentage points in HbA1c from exercise training that ranged from 135 to 270 min of exercise per week for 6 months (13). A similar result was reported in a meta-analysis of 15 papers that suggested regular exercise in patients with T2DM can lose weight and improve HbA1c values (5). Patients T2DM who can improve glycemic control demonstrate decreased rates of chronic complications such as neuropathy, retinopathy, nephropathy, and cardiovascular disease. CONCLUSIONS Twelve wks of aqua-aerobic exercise training improves cardiovascular fitness, glycemic control, and physiological adaptations in older adults with T2DM. Moreover, it may provide additional benefits by reducing the incidence of falls and injuries that occur while performing exercise or while performing activities of daily living. Therefore, it is more than reasonable to conclude that aquatic exercise is a beneficial mode of exercise for elderly patients with type 2 diabetes. ACKNOWLEDGMENTS This study was supported by the 90th anniversary of Chulalongkorn University (Ratchadaphisek somphot endowment fund). Address for correspondence: Nuttamonwarakul A., Inter-department of Biomedical Sciences, Chulalongkorn University, Thailand, 10330. Phone (+66)2 256-4493 Ext. 12; FAX: (+66)2 256-4493 Ext. 17; Email. Apiwan1@gmail.com REFERENCES 1. ACSM, American College of Sports Medicine. Exercise and type II diabetes. Med Sci Sports Exerc. 2000;32:1345-1360. 69 2. ADA, American Diabetes Association. Physical activity, exercise and diabetes. Diabetes Care. 2004;27 (suppl 1):S58-S62. 3. Agurs-Collins TD, Humanyika SK, Ten Have TR. And Adams-Campbell LL. A randomized controlled trial of weight reduction and exercise for diabetes management in older African- American subjects. Diabetes Care. 1997;20:1503-1511. 4. Barbosa TM, Garrido MF and Bragada JA. Physiological adaptations to head-out aquatic exercises with different levels of body immersion. J Strength Cond Res. 2007;21:1255-1259. 5. Boule NG, Haddad E, Kenny GP, Wells GA. And Sigal RJ. Effects of exercise on glycemic control and body mass in type 2 diabetes mellitus: A meta-analysis of controlled clinical trials. JAMA. 2001;286:1218-1227. 6. Broman G, Quintana M, Lindberg T, et al. High intensity deep water training can improve aerobic power in elderly women. Eur J Appl Physiol. 2006;98:117-123. 7. Brum PC, Da Silva GJ, Moreira ED, et al. Exercise training increases baroreceptor gain sensitivity in normal and hypertensive rats. Hypertension. 2000;36(6):1018-1022. 8. Hagberg JM, JE. Graves, M. Limacher, et al. Cardiovascular responses of 70- to 79-yr-old men and women to exercise training. J Appl Physiol. 1989;66:2589-2594. 9. Kingwell BA, Dart AM, Jennings GL, Korner PI. Exercise training reduces the sympathetic component of the blood pressure-heart rate baroreflex in man. Clin Sci (Lond). 1992;82(4):357-362. 10. Mokdad AH, Serdula MK, Dietz WH, et al. The spread of the obesity epidemic in the United States, 1991-1998. JAMA. 1999;282(16):1519-1522. 11. Nahimura K, Yianishi A, Komiyama M, et al. Effects of immersion in different water temperature before exercise on heart rate, cardiac parasympathetic nervous system and rectal temperature. In: The Book of Proceedings of the 1st International Scientific Conference of Aquatic Space Activities. Eds: Nomura T. and Ungerechts BE. Tskuba: University of Tskuba. 2008;128-133. 12. Rogers MA, and WJ. Evans. Changes in skeletal muscle with aging: effects of exercise training. Exerc Sports Sci Rev. 1993;21:65-102. 13. Sigal RJ, Kenny GP, Boulé NG, et al. Effects of aerobic training, resistance training, or both on glycemic control in type 2 diabetes: a randomized trial. Ann Intern Med. 2007;147:357-369. 14. Tajima F, Sagawa S, Iwamoto J, et al. Renal and endocrine response in the elderly during head-out water immersion. Am J Physiol. 1988;23:R977-R983. 15. Takeshima N, Nakata M, Kobayashi F, et al. Oxygen uptake and heart rate differences between walking on land and in water in the elderly. JAPA. 1997;5:126-134. 16. Tessier D, Menard J, Fulop T, et al. Effects of aerobic physical exercise in the elderly with type 2 diabetes mellitus. Arch Gerontol Geriatr. 2000;31:121-132. 70 17. Tsourlou T, Benik A, Dipla K, et al. The effects of a twenty-four week aquatic training program on muscular strength performance in healthy elderly women. J Strength Cond Res. 2006;20(4):811-818. Disclaimer The opinions expressed in JEPonline are those of the authors and are not attributable to JEPonline, the editorial staff or the ASEP organization.
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