Isokinetics and Exercise Science - Volume 19, issue 3

Authors: Baroni, Bruno Manfredini | Stocchero, Cíntia Mussi Alvim | do Espírito Santo, Rafaela Cavalheiro | Ritzel, Cíntia Helena | Vaz, Marco Aurélio

Article Type: Research Article

Abstract: This study investigated knee extensor muscle strength, work and fatigue level under maximal isokinetic concentric and eccentric exercise. Seventeen male athletes were randomized into two groups and performed 10 sets of 10 maximal isokinetic concentric (N =8) or eccentric (N =9) contractions. Knee extensor peak torque and mean torque values per set were 54–121% and 53–133% higher in eccentric compared to concentric exercise, respectively, whereas the percent fall of performance in these …variables was more accentuated in concentric exercise. Total work was significantly higher in eccentric exercise (19475 J) than concentric exercise (15758 J), while fatigue index was greater in concentric (36%) than eccentric (18%) exercise. In conclusion, maximal isokinetic eccentric exercise promotes larger overload to knee extensor muscles than its concentric counterpart due to higher torque produced by the muscle group and also thanks to minor muscle fatigue effects. Show more

Keywords: Knee extensors, concentric exercise, eccentric exercise, task-dependency

DOI: 10.3233/IES-2011-0421

Citation: Isokinetics and Exercise Science, vol. 19, no. 3, pp. 215-220, 2011

Authors: dos Santos Rocha, Clarice Sperotto | Baroni, Bruno Manfredini | Lanferdini, Fábio Juner | de la Rocha Freitas, Cíntia | Frasson, Viviane Bortoluzzi | Vaz, Marco Aurélio

Article Type: Research Article

Abstract: Although previous studies have demonstrated that skeletal muscle adaptations were specific to the types of stimuli, eccentric training studies presented controversial results concerning strength gains in eccentric, isometric and concentric tests. Therefore, the goal of this study was to evaluate torque-velocity adaptations following isokinetic eccentric training protocol using the quadriceps as a model. Twenty physically active men were randomly assigned to a control group (CG; n=10) or to an eccentric training group …(ETG; n=10). Knee extensor torque-velocity relationship including isometric tests and isokinetic tests at 60°/s, 120°/s, 180°/s, 240°/s and 300°/s in concentric and eccentric modes, were assessed before and after a 12-week period of eccentric training (3 sessions/week; 2–5 sets of 7–9 maximal repetitions per session performed at 60°/s along a range of motion 90°). Isokinetic eccentric training significantly increased the knee extensor torque at the training velocity (59%) and at the adjacent velocities (24% at 120°/s and 29% in the isometric test). These results demonstrate the specificity of strength gains in isokinetic eccentric training in relation to contraction type and to angular velocity. Show more

Keywords: Eccentric exercise, muscle adaptation, knee extensor, torque-velocity relationship

DOI: 10.3233/IES-2011-0425

Citation: Isokinetics and Exercise Science, vol. 19, no. 3, pp. 221-226, 2011

Authors: Patlar, Suleyman

Article Type: Research Article

Abstract: This study aimed to examine effects of acute and chronic submaximal exercise on plasma renin and aldosterone levels in football players. Seven apparently healthy, male footballer subjects took part in the study. The subjects were exercised on ergometric bicycles for 20-min at 75% of Max VO_{2} , 3 days a week for 4 weeks. Blood samples were collected on 4 occasions: before the exercise, immediately after the exercise, as well as 2 hours and 24 hours after …the exercise. Plasma renin and aldosterone levels (RIA) were measured. Exercise significantly increased plasma renin and aldosterone levels of the athletes before and after the exercise (p < 0.05). The levels at the 2nd hour following exercise dropped significantly in comparison to those immediately after the exercise (p< 0.05). Plasma values one day after the exercise were significantly lower than those after the 2nd hour (p < 0.05). Consequently, acute and 4-week chronic submaximal exercise have significant effects on plasma renin and aldosterone levels in football players (p< 0.05). Show more

Keywords: Submaximal exercise, renin, aldosterone

DOI: 10.3233/IES-2011-0428

Citation: Isokinetics and Exercise Science, vol. 19, no. 3, pp. 227-230, 2011