The aim of this study was to compare the effect of concentric with eccentric muscle actions on the resulting level of damage to connective tissues by urinary concentration of hydroxyproline. Twenty-one male volunteers were divided into control group (CG), experimental concentric group (ECG), and experimental eccentric group (EEG). The measures of hydroxyproline were performed at three times: pretest, fourth week, and posttest. Biceps curl and chest press exercises also were performed with three sets of 10 repetitions two times per week for both experimental groups. Analysis of variance (ANOVA) showed a significant difference between pretest of the CG and pretest of the ECG (p = 0.002), and between pretest and posttest for the EEG (p = 0.029). Therefore, this study concluded that the level of damage to the connective tissue is greater when exercises involving eccentric muscle actions are performed. The continuity of training, however might reduce this damage.
Purpose. The purpose of this study was to compare the effects of concentric with eccentric muscle actions on strength gains. Methods. Forty-two untrained men were randomly divided into three groups: the concentric experimental (cE), the eccentric experimental (EE) and a control (c). The cE group performed only concentric muscle actions at 80% of one repetition maximum (1 RM) and the EE group performed only eccentric muscle actions at 120% of 1 RM. Both groups trained by performing three sets of 10-12 repetitions for eight weeks of biceps curl (Bc) and bench press (BP) exercises. The c group did not engage in any type of training. Results. Analyses performed within the cE group found that there were significant improvements in muscle strength in the eighth week of BP ( % = 26.9%, p = 0.01) and in the fourth and eighth week of Bc ( % = 22.1%, p = 0.00 and % = 32.1%, p = 0.00, respectively). Analyses of the EE group found that there were significant improvements in muscle strength in the fourth and eighth week of BP ( % = 13.7%, p = 0.00 and % = 28.4%, p = 0.00, respectively). Between the two groups (cE versus EE), comparisons showed that the cE group performed significantly better than the EE group in the fourth and eighth week of Bc (p = 0.00 and p = 0.00, respectively). Conclusions. These findings indicate that those who do not train should perform concentric muscle actions in the first 8 weeks of training in order to generate accelerated strength improvement.
Cardiovascular overload may be determined by heart rate (HB), blood pressure (BP) and by the double product (DP). This investigation has as objective: To compare the cardiovascular overload, from acute responses of HB,BP and DP in three investigative phases. It was necessary then, that seven men with mean age of 26.7 ± 0.1 years were assigned to do the following: they were measures for BP and HB with no training (control phase). 48 hours later, they were measured for BP and HB pre and post-3 x 10 RM strength training, with combined concentric and eccentric muscle actions (combined stage), and 72 hours later, they were measured of BP and HB pre and post-3 x 10RM strength training, with isolated absolute eccentric muscle actions (eccentric phase). Statistal analysis, (ANOVA for repeated measures) for means of systolic (SBP) and diastolic (DBP) BP, of HR and DP between phases, showed the variables studied in the control phase were are signifi cantly inferior than the other two phases (p = 0.000 and 0.000). However, means of the SBP, DBP and of HB, obtained in the eccentric phase, although smaller, were not signifi cantly inferior to those obtained in the combined phase (p = 0.316, 0.831 and 0.066) respectively. However, DP obtained with the absolute isolated eccentric muscle actions is signifi cantly inferior than the combined muscle actions (p = 0.027). Thus, it is possible to state that absolute isolated eccentric muscle actionsmay be more adequated when there is a need for a lesser overload on the heart during strength training.
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