Rodrigo Hohl

Vitamin C and E Supplementation Effects in Professional Soccer Players Under Regular Training

Exercise training is known to induce an increase in free radical production potentially leading to enhanced muscle injury. Vitamins C and E are well known antioxidants that may prevent muscle cell damage. The purpose of this study was to determine the effects of these supplemental antioxidant vitamins on markers of oxidative stress, muscle damage and performance of elite soccer players. Ten male young soccer players were divided into two groups. Supplementation group (n = 5) received vitamins C and E supplementation daily during the pre-competitive season (S group), while the placebo group (PL group, n = 5) received a pill containing maltodextrin. Both groups performed the same training load during the three-month pre-season training period. Erythrocyte antioxidant enzymes glutathione reductase, catalase and plasma carbonyl derivatives did not show any significant variation among the experimental groups. Similarly, fitness level markers did not differ among the experimental groups. However, S group demonstrated lower lipid peroxidation and muscle damage levels (p < 0.05) compared to PL group at the final phase of pre-competitive season. In conclusion, our data demonstrated that vitamin C and E supplementation in soccer players may reduce lipid peroxidation and muscle damage during high intensity efforts, but did not enhance performance.

Development and characterization of an overtraining animal model.

PURPOSE Development of an endurance training-overtraining protocol for Wistar rats that includes increased workload and is characterized by analyses of performance and biomarkers. METHODS The running protocol lasted 11 wk: 8 wk of daily exercise sessions followed by 3 wk of increasing training frequency (two, three, and four times), with decreasing recovery time between sessions (4, 3, and 2 h) to cause an imbalance between overload and recovery. The performance tests were made before training (T1) and after the 4th (T2), 8th (T3), 9th (T4), 10th (T5), and 11th (T6) training weeks. All rats showed significantly increased performance at T4, at which time eight rats, termed the trained group (Tr), were sacrificed for blood and muscle assays. After T6, two groups were distinguishable by differences in the slope (alpha) of a line fitted to the individual performances at T4, T5, and T6: nonfunctional overreaching (NFOR; alpha < -15.05 kg x m) and functional overreaching (FOR; alpha >or= -15.05 kg x m). RESULTS Data were presented as mean +/- SD. FOR maintained the performance at T6 similar to Tr at T4 (530.6 +/- 85.3 and 487.5 +/- 61.4 kg x m, respectively). The FOR and the Tr groups showed higher muscle citrate synthase activity (approximately 40%) and plasma glutamine/glutamate ratio (Gm/Ga; 4.5 +/- 1.7 and 4.5 +/- 0.9, respectively) than the sedentary control (CO) group (2.8 +/- 0.5). The NFOR group lost the performance acquired at T4 (407.3 +/- 88.2 kg x m) after T6 (280.5 +/- 93.1 kg x m) and exhibited sustained leukocytosis. NFORs Gm/Ga (3.1 +/- 0.2) and muscle citrate synthase activity were similar to CO values. CONCLUSIONS The decline in performance in the NFOR group could be related to the decrease in muscle oxidative capacity. We observed a trend in the Gm/Ga and leukocytosis that is similar to what has been sometimes observed in overtrained humans. This controlled training-overtraining animal model may be useful for seeking causative mechanisms of performance decline.

Is lactate production related to muscular fatigue? A pedagogical proposition using empirical facts

The cause-effect relationship between lactic acid, acidosis, and muscle fatigue has been established in the literature. However, current experiments contradict this premise. Here, we describe an experiment developed by first-year university students planned to answer the following questions: 1) Which metabolic pathways of energy metabolism are responsible for meeting the high ATP demand during high-intensity intermittent exercise? 2) Which metabolic pathways are active during the pause, and how do they influence phosphocreatine synthesis? and 3) Is lactate production related to muscular fatigue? Along with these questions, students received a list of materials available for the experiment. In the classroom, they proposed two protocols of eight 30-m sprints at maximum speed, one protocol with pauses of 120 s and the other protocol with pauses of 20 s between sprints. Their performances were analyzed through the velocity registered by photocells. Blood lactate was analyzed before the first sprint and after the eighth sprint. Blood uric acid was analyzed before exercise and 15 and 60 min after exercises. When discussing the data, students concluded that phosphocreatine restoration is time dependent, and this fact influenced the steady level of performance in the protocol with pauses of 120 s compared with the performance decrease noted in the protocol with pauses of 20 s. As the blood lactate levels showed similar absolute increases after both exercises, the students concluded that lactate production is not related to the performance decrement. This activity allows students to integrate the understanding of muscular energy pathways and to reconsider a controversial concept with facts that challenge the universality of the hypothesis relating lactate production to muscular fatigue.

Interaction between Overtraining and the Interindividual Variability May (Not) Trigger Muscle Oxidative Stress and Cardiomyocyte Apoptosis in Rats

Severe endurance training (overtraining) may cause underperformance related to muscle oxidative stress and cardiomyocyte alterations. Currently, such relationship has not been empirically established. In this study, Wistar rats (n = 19) underwent eight weeks of daily exercise sessions followed by three overtraining weeks in which the daily frequency of exercise sessions increased. After the 11th training week, eight rats exhibited a reduction of 38% in performance (nonfunctional overreaching group (NFOR)), whereas eleven rats exhibited an increase of 18% in performance (functional overreaching group (FOR)). The red gastrocnemius of NFOR presented significantly lower citrate synthase activity compared to FOR, but similar to that of the control. The activity of mitochondrial complex IV in NFOR was lower than that of the control and FOR. This impaired mitochondrial adaptation in NFOR was associated with increased antioxidant enzyme activities and increased lipid peroxidation (in muscle and plasma) relative to FOR and control. Cardiomyocyte apoptosis was higher in NFOR. Plasma creatine kinase levels were unchanged. We observed that some rats that presented evidence of muscle oxidative stress are also subject to cardiomyocyte apoptosis under endurance overtraining. Blood lipid peroxides may be a suitable biomarker for muscle oxidative stress that is unrelated to severe muscle damage.

Glutamine and Glutamate Reference Intervals as a Clinical Tool to Detect Training Intolerance During Training and Overtraining

1.1 Training and overtraining A training process consists of a sum of repeated exercise sessions with gradual overloads that are performed in a systematised and programmed way. The workload can be manipulated through variables such as weight load resistance, speed, duration, pauses between stimuli, muscular action, movement speed, amplitude, weekly frequency, number of sessions per day, number of exercises per session and the combination of different exercises in the same session. Exercise triggers the synthesis of several enzymes and structural proteins that adapt tissues, organs and systems to changes in cellular homeostasis, in a task-oriented way and depending on the exercise stimulus. This set of chronic physiological and metabolic changes, currently termed supercompensation, allows for a more efficient and sustainable physiological environment during voluntary physical activity. Supercompensation supplies energy economy for habitual physical activities or enhances the energy supply during exercises of high metabolic demands. Recently, our group demonstrated, using proteomic analyses of rat muscle, that only one stimulus of exhaustive, incremental exercise (approximately 30 min) is enough to produce an acute, generalised, metabolic response in the muscular fibre (Gandra et al., 2010). This probably occurs to minimise the stress that will occur in a subsequent exercise session and, in the long term, the cumulative effects of exercise on gene expression lead to specific muscle phenotypic alterations, which is a major aspect of performance enhancement. However, supercompensation is only achieved when the ratio between overload and recovery time is individually balanced. Damaged tissue structures resulting from the exercise stimulus are repaired during recovery, when rest and food intake are crucial for the energy supply that is required for the synthesis of new proteins and cellular components.

Lactate production retards, not causes, acidosis: a theoretical approach for physical education students.

The content of numerous textbooks of exercise physiology, biochemistry and even many papers in the current literature explain acidosis during intense exercise by the production of lactic acid, causing the release of a proton with lactate as the final product. However, lactate production retards not cause acidosis. To understand better the importance of training schedules features and to do a correct interpretation of blood lactate measurements during different kinds of exercise, the goal of this work is to present a practical approach carried out with physical education students that allows the discussion of these concepts with real datas, breaking the myth involving this subject. Firstly, the students were conduct to plan different exercise protocols (continuous versus intermittent) where the average speed and blood lactate were measured. After the exercise protocols done, the students did some correlation among blood lactate, fatigue index and performance datas. The results show that there is not a clear relationship between blood lactate and fatigue, independently of exercise type that is being considered. By this way, it is possible to build with the students a new view of this polemic subject (blood lactate and fatigue) through a simple practical approach, helping the students to understand better metabolic aspects involved with physical exercises.