Red blood cell-nitric oxide synthase (RBC-NOS)-dependent NO production is essential for the maintenance of RBC deformability, which is known to improve oxygen supply to the working tissue. Electrostimulation of the whole body (WB-EMS) has been shown to improve maximal strength, springiness, and jumping power of trained and untrained athletes. To examine whether these 2 parameters are associated, this study, for the first time, aimed to investigate the effects of an 18-week dynamic WB-EMS program on RBC deformability in addition to maximal strength performance (1 repetition maximum [1RM]) in elite soccer players. Fifteen test persons were assigned in either WB-EMS group (EG, n = 10) or training group (TG, n = 5). Next to their weekly training sessions, EG performed 3 × 10 squat jumps under the influence of WB-EMS twice per week between weeks 1 and 14 and once per week between weeks 14 and 18. Training group only performed 3 × 10 squat jumps. Performance was assessed by a maximal strength test on the leg press machine (1RM). Subjects were tested at baseline and after weeks 7, 14, and 18 with blood sampling before (Pre), 15-30 minutes after (Post), and 24 hours after (24-hour Post) the training. The results showed that maximal strength was significantly improved in EG (p < 0.01). Maximum RBC deformability (EImax) increased on EMS stimulus in EG while it remained unaffected in the TG. Acute increase in EImax at baseline was explained by an increase in RBC-NOS activation while chronic increase of deformability must be caused by different, yet unknown, mechanisms. EImax decreased between weeks 14 and 18 suggesting that 1 WB-EMS session per week is not sufficient to alter deformability (EImax). In contrast, the deformability at low shear stress (EI 3 Pa), comparable with conditions found in the microcirculation, significantly increased in EG until week 14, whereas in TG deformability only, increased until week 7 due to increasing training volume after the winter break. The results indicate that WB-EMS represents a useful and time-saving addition to conventional training sessions to improve RBC deformability and possibly oxygen supply to the working tissue and thus promoting general force components in high performance sport.
Analyses of game sports or of performances shown in them require appropriate models. Many game sports can be modelled as complex, dynamic systems. This study investigated how recurrence plots (RPs) -a method to analyse complex systems -and the analyses of RPs can be applied to the game sports golf and soccer. A golfer is treated as a complex system with many unknown components. The scalar variable Shots Saved can describe his/her behaviour. Phase space reconstruction is needed to unfold hidden facets of a golfer's behaviour. Results indicate that golfers' performances do not approach a stable state, but seem rather unpredictable. A soccer match can also be treated as a complex system. Some components -the players -and their respective behaviour represented by movement trajectories are known and can be used to describe the system's behaviour. We propose that no embedding is needed for the RP construction in this case. Results indicate that the more goal shots there are in a game, the more unstructured it is. Furthermore, if several golfers or soccer matches are investigated, we recommend using the same RP parameters to achieve comparable results. ARTICLE HISTORY
The study aims at modeling soccer matches with recurrence quantification analysis (RQA). Positional data of 12 soccer matches from German Bundesliga out of the season 2009/2010 are used to produce global and local recurrence plots (RP) and perform the RQA. It is shown that RPs are representations of the soccer matches and the RQA parameters deliver descriptions of the matches.
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