Maintenance of Changes in Glycemic Control and Blood Lipids following 12 Weeks of Underwater Treadmill Training in Adults with Type 2 Diabetes

Objective: To document short- and long-term effects of a 12-week aquatic exercise walking program on glycemic control and blood lipid profile in middle-aged adults with type 2 diabetes.

Research Design and Methods: Thirteen adults with type 2 diabetes (age = 59.5 ± 4.5 years; 7 females, 6 males) completed 12 weeks of underwater treadmill training (UTT) (3d·wk^-1), followed by a 12 weeks of no UTT. During UTT, exercise intensity and duration were systematically and progressively increased from 40-50% of heart rate reserve (HRR) and 30 minutes (3 x 10-min bouts) in Week 1 to 50-70% HRR and 60 minutes (3 x 20-min bouts) in Week 12. During the 12-week period following completion of UTT, study participants were asked to maintain their current diet and allowed to engage in any type or volume of physical activity, with the exception of structured exercise programming. Primary outcome variables included glycosylated hemoglobin (HbA1c), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and the TG/HDL ratio (TG/HDL). Data obtained before UTT, immediately following UTT, and 3 months after the end of UTT were analyzed using 1-way repeated measures analysis of variance.

Results: Compared to baseline values, HbA1c was reduced (7.8% to 7.3%) and HDL-C was increased (43.5 mg/dl to 50.6 mg/dl) following UTT (p < .05). After completion of the 3-month maintenance period, HbA1c was lower (p < .05) compared to baseline (7.4% vs. 7.8%), but HDL-C was not different (p > .05) from the pre-UTT level (48.4 mg/dl vs. 43.5 mg/dl).

Conclusions: Our findings demonstrate that among middle-aged adults with type 2 diabetes, improvement in glycemic control after 12 weeks of underwater treadmill training persisted three months following cessation of UTT, but training-induced increases in HDL were not maintained.