Exercise performed around MLSS decreases systolic blood pressure and increases aerobic fitness in hypertensive rats

BACKGROUND: Exercise is a non-pharmacologic agent widely used for hypertension control, where low intensity is often associated with blood pressure reduction. Maximal lactate steady state (MLSS) was recently identified in spontaneously hypertensive rats (SHRs) as an important step in establishing secure intensities for prescribing exercise for hypertensive phenotypes. Here we verified the effects of training around MLSS, 20% below MLSS, and 15% above MLSS on aerobic fitness and blood pressure status of SHR. Eighteen-week-old SHRs (n = 5, ~ 172.4 ± 8.1 mm Hg systolic blood pressure) were trained on a treadmill for 4 weeks for 30 min/day, 5 days/week at a velocity of 20 m.min(−1). After training, a novel MLSS and incremental test was performed to evaluate the animals’ aerobic fitness. Furthermore, ~ 22-week-old SHRs (n = 12, ~169.8 ± 13.8 mm Hg systolic blood pressure) were divided into non-exercised (CG, n = 4), low intensity (LIG, n = 4) and high intensity (HIG, n = 4) groups, where rats were trained at 16 m.min(−1) and 23 m.min(−1) respectively for 30 min/day, 5 days/week for 4 weeks. RESULTS: Exercise performed at MLSS enhanced aerobic fitness, leading to a novel MLSS, identified around 30 m.min(−1). Low and high intensity training reduced systolic blood pressure and only high intensity training led to improved aerobic fitness (28.1%, p < 0.01). CONCLUSIONS: Therefore, our data indicate a decrease in blood pressure due to low and high exercise intensity, and an increase in aerobic fitness provided by high-intensity exercise in SHRs.