Influência do treinamento de força em diferentes intensidades sobre o decurso temporal da educação cruzada de força e potência musculares

Abstract

Cross education is a neural adaptation that occurs in the homologous muscles (contralateral muscles) after unilateral training, increasing muscle strength. Objective: To verify the impact of resistance training at different load intensities on the time course of cross-education of muscle strength (maximum dynamics, maximum isometric) and muscle power. Methods: Fifty subjects were randomized into three groups: higher-intensity strength training [G80: two series with 80% and two series with 40% of one maximum repetition (1RM)], lower-intensity strength training (G40: 4 series with 40% of 1 RM) or control group (CG). G40 and G80 completed four weeks of unilateral resistance training (URT) elbow flexion, three times a week, with the rapid concentric phase and the controlled eccentric phase. Maximum dynamic muscle strength (one repetition = 1RM), maximum voluntary isometric contraction (MVIC) and muscle power (strength x speed) at 40% and 80% of 1RM were assessed at baseline and after one (week 1) and four weeks (week 4) of URT. Results: in the untrained arm, G80 increased progressively by 1RM (baseline <week 1 <week 4; P <0.05), while G40 showed an increase of 1RM only in the week 4 (baseline =week 1 < week 4; P <0.05). There was no increase in MVIC after one week of training. However, after four weeks, only G80 increased (P <0.05) MVIC. The crosseducation of muscle power equally evolved in the power tests at 40 and 80% of 1RM; with URT with lower intensity, produced an increase in muscle power in 1 week, maintaining it in week 4. In contrast, URT with higher resistance promoted progressive increases, starting from week 1, in the muscle power produced at 40% and 80% of 1RM, (baseline <week 1 <week 4; P <0.05). Conclusion: In the initial phase of the URT (one week), only higher-intensities URT promote cross-education of dynamic strength. However, the increase in muscle power is independent of intensity. In 4 weeks (later phase), lower-intensities URT promotes crosseducation of dynamic strength. However, there is progression in the gain of muscle strength and muscle power until week 4 and isometric strength gain with higher-intensity URT.