Rol de la intención en la terminación del ejercicio inducida por la fatiga. Aproximación no-lineal

Intention has a well-recognised role in the termination point of fatigue-induced exercise; however its interaction with physiological factors is unknown. The linear causal model applied to mind-body relationships does not explain several characteristic phenomena related to the termination point in tasks defined by motor intention. This paper aims to investigate the role of intention in terminating exercise and reveal the non-linear psychobiological integration that occurs during fatiguing efforts. On the basis of the experimental results, we conclude that the mechanism responsible for termination is the dissolution of the intentional attractor that is produced by the growing instability that fatigue produces in the neuromuscular axis. These findings point to the existence of a non-linear, dynamic psychobiological integration in exercise-induced fatigue

Monitoring the dynamics of exhausting exercises: the time-variability of acceleration

Fatigue has been related to changes in the time-variability properties of coordinative variables during an exhausting isometric exercise [1]. In this study we aimed to investigate the qualitative changes in acceleration (kinematic collective variable) during exhausting running (n= 8) and ski mountaineering (n males = 5, n females = 5) exercises. Time-variability of acceleration was calculated using the Multifractal Detrended Fluctuation Analysis (MFDFA). Initial and final time series of both exercises were compared through Wilcoxon test. A reduction of MFDFA spectrum was observed in the final period in both exercises while the participants approached exhaustion, except for the male group of ski mountaineers that increased their speed at the end of the exercise. In runners, those who approached the psychobiological exhaustion showed a higher reduction in the MFDFA spectrum compared to those who did not. Although more research is needed to model this dynamic behavior in front of different constraints, time-variability of acceleration throughout a multifractal application seems to provide a valid information about the system adaptation during exhausting dynamic exercises

El foco de atención emerge espontáneamente durante el ejercicio progresivo y máximo

The objective of this study was to test a non-linear focus-of-attention model, with the imposition and non-imposition of dissociative thinking during a progressive and maximum bicycle ergometer test. Twelve students who were familiar with experimental procedures performed a progressive and maximum bicycle ergometer test twice under two different conditions: first so as to encourage the emergence of intrinsic dynamics, without imposing any type of thinking and, second, imposing dissociative thinking (DT). During the test, through previously agreed signals, the participants reported on their type of thinking every 30 seconds (DT or AT - dissociative or associative thinking). The individual series were divided into 10 temporary intervals of increasing intensity and the percentage of DT and AT in each one of them was calculated. The median percentage of AT was significantly higher from the 6th interval of intensity onwards in the non-imposed DT test (NIDT) (χ2 (12, 9) = 39.75; p < .001) and from the 8th interval onwards in the imposed DT test (IDT) (χ2 (12, 9) = 70.65; p < .001). The percentage of PD was higher in the PDI test in 6 of the 10 intervals of intensity (p < .05). The results demonstrate the spontaneous emergence of PA during a progressive and maximum cycling exercise, confirming the nonlinear focus-of-attention model.El objetivo de este estudio fue testar un modelo no lineal del foco de atención imponiendo y sin imponer un pensamiento disociado durante un test cicloergométrico progresivo y máximo. Doce estudiantes previamente familiarizados con los procedimientos experimentales realizaron dos veces un test progresivo y máximo en cicloergómetro en dos condiciones diferentes: la primera, orientada a establecer su dinámica intrínseca, sin imponer ningún tipo de pensamiento, y la segunda imponiendo un pensamiento disociado (PD). Durante los test los participantes informaron cada 30s sobre su tipo de pensamiento (PD o PA -pensamiento asociado) a través de señales previamente convenidas. Las series individuales se dividieron en 10 intervalos temporales de intensidad creciente y se calcularon los porcentajes de PD y PA en cada una de ellas. Se encontraron porcentajes significativamente superiores de PA a partir del 6º intervalo de intensidad en el test con PD no impuesto (PDNI) (χ2 (12, 9) = 39.75; p < .001) y a partir del 8º intervalo en el test con PD impuesto (PDI) (χ2 (12, 9) = 70.65; p < .001). Los porcentajes de PD fueron superiores en el test PDI en 6 de los 10 intervalos de intensidad (p < .05). Los resultados demuestran la emergencia espontánea de PA durante el ejercicio progresivo y máximo confirmando el modelo no lineal del foco de atención.O objectivo deste estudo foi testar um modelo não linear do foco de atenção impondo e sem impor um pensamento dissociativo durante um teste cicloergométrico progressivo e máximo. Doze estudantes previamente familiarizados com os procedimentos experimentais realizaram duas vezes um teste progressivo e máximo num cicloergómetro em duas condições diferentes: a primeira, orientada para estabelecer a sua dinâmica intrínseca, sem impor nenhum tipo de pensamento, e a segunda impondo um pensamento dissociado (PD). Durante os testes os participantes informaram cada 30s sobre o seu tipo de pensamento (PD ou PA -pensamento associado) através de sinais previamente convencionados. As séries individuais dividiram-se em 10 intervalos temporais de intensidade crescente e foram calculadas as percentagens de PD e PA em cada uma delas. Verificaram-se percentagens significativamente superiores de PA a partir do 6º intervalo de intensidade no teste com PD não imposto (PDNI) (χ2 (12, 9) = 39.75; p < .001) e a partir do 8º intervalo no teste com PD imposto (PDI) (χ2 (12, 9) = 70.65; p < .001). As percentagens de PD foram superiores no teste de PDI em 6 dos 10 intervalos de intensidade (p < .05). Os resultados demonstram a emergência espontânea de PA durante o exercício progressivo e máximo, confirmando o modelo não linear do foco atencional

Metastable Pain-Attention Dynamics during Incremental Exhaustive Exercise

Background: Pain attracts attention on the bodily regions. Attentional allocation toward pain results from the neural communication across the brain-wide network “connectome” which consists of pain-attention related circuits. Connectome is intrinsically dynamic and spontaneously fluctuating on multiple time-scales. The present study delineates the pain-attention dynamics during incremental cycling performed until volitional exhaustion and investigates the potential presence of nested metastable dynamics. Method: Fifteen young and physically active adults completed a progressive incremental cycling test and reported their discomfort and pain on a body map every 15 s. Results: The analyses revealed that the number of body locations with perceived pain and discomfort increased throughout five temporal windows reaching an average of 4.26 ± 0.59 locations per participant. A total of 37 different locations were reported and marked as painful for all participants throughout the cycling task. Significant differences in entropy were observed between all temporal windows except the fourth and fifth windows. Transient dynamics of bodily locations with perceived discomfort and pain were spanned by three principal components. The metastable dynamics of the body pain locations groupings over time were discerned by three time scales: (1) the time scale of shifts (15 s); (2) the time scale of metastable configurations (100 s), and (3) the observational time scale (1000 s). Conclusion: The results of this study indicate that body locations perceived as painful increase throughout the incremental cycling task following a switching metastable and nested dynamics. These findings support the view that human brain is intrinsically organized into active, mutually interacting complex and nested functional networks, and that subjective experiences inherent in pain perception depict identical dynamical principles to the neural tissue in the brain

Soft-Assembled Multilevel Dynamics of Tactical Behaviors in Soccer

This study aimed to identify the tactical patterns and the timescales of variables during a soccer match, allowing understanding the multilevel organization of tactical behaviors, and to determine the similarity of patterns performed by different groups of teammates during the first and second halves. Positional data from 20 professional male soccer players from the same team were collected using high frequency global positioning systems (5 Hz). Twenty-nine categories of tactical behaviors were determined from eight positioning-derived variables creating multivariate binary (Boolean) time-series matrices. Hierarchical principal component analysis (PCA) was used to identify the multilevel structure of tactical behaviors. The sequential reduction of each set level of principal components revealed a sole principal component as the slowest collective variable, forming the global basin of attraction of tactical patterns during each half of the match. In addition, the mean dwell time of each positioning-derived variable helped to understand the multilevel organization of collective tactical behavior during a soccer match. This approach warrants further investigations to analyze the influence of task constraints on the emergence of tactical behavior. Furthermore, PCA can help coaches to design representative training tasks according to those tactical patterns captured during match competitions and to compare them depending on situational variables

Iron oxide-modified nanoporous geopolymers for arsenic removal from ground water

Composite materials of hierarchically porous geopolymer and amorphous hydrous ferric oxide were produced and characterized as a new potentially cost-effective arsenic adsorbent. The arsenic removal capabilities of the iron (hydr)oxide (HFO) media were carried out using batch reactor experiments and laboratory scale continuous flow experiments. The Rapid Small-Scale Column Tests (RSSCT) were employed to mimic a scaled up packed bed reactor and the toxicity characteristic leaching procedure (TCLP) test of arsenic adsorbed solid material was carried out to investigate the mechanical robustness of the adsorbent. The best performing media which contained ~20 wt% Fe could remove over 95?µg of arsenic per gram of dry media from arsenic only water matric. The role of the high porosity in arsenic adsorption characteristics was further quantified in conjunction with accessibility of the adsorption sites. The new hierarchically porous geopolymer-based composites were shown to be a good candidate for cost-effective removal of arsenic from contaminated water under realistic conditions owing to their favorable adsorption capacity and very low leachability

Local Pain Dynamics during Constant Exhaustive Exercise

The purpose of this study was to delineate the topological dynamics of pain and discomfort during constant exercise performed until volitional exhaustion. Eleven physical education students were tested while cycling and running at a “hard” intensity level (e.g., corresponding to Borg’s RPE (6–20) = 15). During the tests, participants reported their discomfort and pain on a body map every 15s. “Time on task” for each participant was divided into five equal non-overlapping temporal windows within which their ratings were considered for analysis. The analyses revealed that the number of body locations with perceived pain and discomfort increased throughout the five temporal windows until reaching the mean (± SE) values of 4.2 ± 0.7 and 4.1 ± 0.6 in cycling and running, respectively. The dominant locations included the quadriceps and hamstrings during cycling and quadriceps and chest during running. In conclusion, pain seemed to spread throughout the body during constant cycling and running performed up to volitional exhaustion with differences between cycling and running in the upper body but not in the lower body dynamics