No abstract

No abstract

ResumoFatigue can be considered a complex phenomenon, related to the decrease of motivational factors, strength sustentation reduction and feeling of exhaustion. The objective of this review was to describe the two main models described about fatigue: inability of the physiological systems and the central government models. Over 13 months articles were identified and reviewed, in the main databases, using the words fatigue, peripheral fatigue, central fatigue, central government and exercise in English and Portuguese. For this review 37 productions were used, 19 of these were experimental studies and 18 others papers. The inability of physiological systems describes that the fatigue is a homeostasis breakage and, as has as final consequence, exhaustion. According to this model, the fatigue comes from inability of the physiological systems in both levels: central and peripheral. The central fatigue is characterized by changes in concentration or actions of branched chain amino acids, dopamine, choline and acetylcholine, cytokines, ammonia and carbohydrates. The peripheral fatigue is by changes in concentrations of creatine phosphate, glycogen and lactate -pH related. The central government describes that the fatigue starts without evidence of correlated failures to homeostasis and the brain acts as a central government in order to ensure that the exercise is finished. Is concluded that in inability of the physiological systems model, the body is analyzed as a single segment and not as an integrated system in which complex functions are performed, the main of all, the maintenance of homeostasis.

No abstract

Paddles and fins are used in swimmers training with different objectives (e.g., increase propulsive areas of hands and feet, improve the feeling of water flow). These artificial modifications of the stroke might be viewed as external constraints of the stroke task, both will either disturb or facilitate swimming modalities, so the coaches should manipulate its use to extract benefits for performance. This study seeks to investigate the precise effects of wearing either paddles (PAD) or fins (FINS) vs. a no-equipment (NE) trial in three all-out front crawl exercises on swimmer kinematics, arm stroke efficiency (ηp), upper-limbs coordination patterns (Index of Coordination, IdC), and estimated energy cost (C). Eleven regional to national-level male swimmers participated in the study (age: 25.8 ± 5.5 years, body mass: 75.2 ± 5.5 kg, height: 177 ± 6.5 cm) and were recorded from both sides of the swimming pool to collect all variables. Repeated measures ANOVA and Bonferroni post hoc were used to compare the variables. Effects sizes were calculated. Time to cover the distance and velocity were higher in FINS swimming, with larger values of stroke length (SL) and lower kick amplitude in comparison to the other trials (PAD and NE). The use of FINS also modified the stroke phases durations by presenting significant lower propulsion time during the stroke in comparison to PAD or NE. Values of IdC were lower (IdC < −1%, so catch-up pattern of coordination) for FINS in comparison to NE. In terms of ηp, using PAD or FINS demonstrate higher arm stroke efficiency than swimming without equipment. Finally, C was significantly higher in FINS swimming in comparison to NE and PAD. From the present results, it should be noted that the use of equipment such as fins deeply modify the structure of the swimming stroke (from the performance-related parameters through the kinematics of both upper and lower limbs to the stroke efficiency and coordination pattern). So, using equipment should be appropriately scaled by the coaches to the objectives of the training session in swimming, and in emergent sports such as “SwimRun”, paddles and fins must be viewed as tools to achieve higher velocities to cover a given distance.