Cardiovascular effects of exercise training in spontaneously hypertensive rats: A systematic review and meta-analysis

Exercise is recommended as a nonpharmacological intervention to lower blood pressure in individuals with hypertension, yet optimal exercise parameters and physiological factors influencing its effectiveness remain incompletely understood. We conducted a meta-analysis to quantify the effects of treadmill-based exercise training in spontaneously hypertensive rats (SHR), a well-established animal model of hypertension. A systematic literature search identified 116 studies reporting systolic blood pressure (SBP), mean arterial pressure (MAP), or resting heart rate (RHR). Random-effects models showed that exercise significantly improved cardiovascular outcomes, with large effect sizes and substantial heterogeneity observed for SBP (-1.19 (Hedges' g); 95% CI: -1.43 to -0.94; p < 0.001; I² = 81.2%), MAP (-1.06 (Hedges' g); 95% CI: -1.27 to -0.85; p < 0.001; I² = 66.2%), and RHR (-1.02; 95% CI: -1.23 to -0.81; p < 0.001; I² = 71.6%). Subgroup analyses revealed that exercise intensity, sex, and age partially accounted for SBP variability. For MAP, heterogeneity was associated with exercise intensity, sex, and duration of exercise training, while RHR was driven by exercise intensity alone. These findings confirm the benefits of treadmill-based exercise on cardiovascular health in SHRs and demonstrate the importance of physiological and training-related factors in modulating the cardiovascular response.