Effect of aquatic exercise on cardiovascular fitness in people with type 2 diabetes mellitus: a systematic review and meta-analysis.

Aims    To systematically review and meta-analyze the impact of aquatic exercise (AE) on cardiovascular health in patients with type 2 diabetes mellitus (T2DM).Material and methods    Relevant literature about AE in patients with T2DM up to May 25, 2021, were collected from the PubMed, the Cochrane, EMBASE, Web of Science, and Ovid databases. The main outcomes were 6­min walking distance (6MWD) and maximal oxygen uptake (VO2max). Secondary outcomes were resting heart rate (RHR) and resting systolic (RSBP) and diastolic blood pressures (RDBP).Results    12 articles including 320 participants were identified. Among them, three trials compared AE to land-based exercise (LE), six compared AE to non-intervention control (Ctrl), and three were pre- / post-AE design without a control group. Meta-analysis showed that compared with baseline, VO2max increased (WMD=0.71, 95 %CI 0.47 to 0.94), while RHR, RSBP and RDBP declined (WMD=-5.88, 95 %CI -6.88 to -4.88; WMD=-5.76, 95 %CI -7.75 to -3.78; WMD= -2.48, 95 %CI -3.83 to -1.13, respectively) post-AE. 6WMD and VO2max increased (WMD=127.00, 95 %CI 49.26 to 204.74; WMD=2.02, 95 %CI 1.66 to 2.38, respectively) and RHR declined (WMD=-4.20, 95 %CI -6.36 to -2.03, AE vs Ctrl) when AE was compared to Ctrl. There were no significant differences in the above indicators between AE and LE.Conclusions    AE, like LE, increases VO2max, and reduces RHR, RSBP, and RDBP. These responses may improve cardiovascular health in patients with T2DM. However, more data are needed to confirm the effect of AE on 6MWD in T2DM patients.