A characterization of dynamic resistance training-induced skeletal muscle adaptations in hypertensive rats

Resistance training (RT) is commonly recommended to increase muscle strength and to complement aerobic training for managing hypertension. However, the effects of RT on muscle adaptations in hypertensive individuals are not well understood. This study evaluated RT-induced muscular changes in spontaneously hypertensive rats (SHRs). Thirty-two adult SHRs were divided into four groups: sedentary females (SF), trained females (TF), sedentary males (SM), and trained males (TM). The trained groups underwent moderate-intensity dynamic RT 5 days per week for 8 weeks. Muscle assessments included measuring phosphofructokinase (PFK) activity, myosin heavy chain (MHC) expression, and fiber type. Blood pressure (BP) was measured directly. The results showed increased type IIB fibers in the trained females (TF) and more intermediate fibers in the trained males (TM). Trained rats displayed higher PFK activity and MHC IIB expression in the plantaris muscle. There were positive correlations between the maximal load test (MLT) and MHC IIB expression in all groups, MLT and intermediate fibers in males, and MLT and IIB fibers in females. No significant changes in BP were observed following the training period. These results suggest that RT promotes beneficial muscle adaptations in both sexes, with some sex-specific differences in fiber composition. Although BP was unchanged, the findings support RT as a strategy to improve functional capacity in this population.