Cardiorespiratory coordination in repeated maximal exercise

Increases in cardiorespiratory coordination (CRC) after training with no differences in performance and physiological variables have recently been reported using a principal component analysis approach. However, no research has yet evaluated the short-term effects of exercise on CRC. The aim of this study was to delineate the behavior of CRC under different physiological initial conditions produced by repeated maximal exercises. Fifteen participants performed 2 consecutive graded and maximal cycling tests. Test 1 was performed without any previous exercise, and Test 2 6 min after Test 1. Both tests started at 0 W and the workload was increased by 25 W/min in males and 20 W/min in females, until they were not able to maintain the prescribed cycling frequency of 70 rpm for more than 5 consecutive seconds. A principal component (PC) analysis of selected cardiovascular and cardiorespiratory variables (expired fraction of O2, expired fraction of CO2, ventilation, systolic blood pressure, diastolic blood pressure, and heart rate) was performed to evaluate the CRC defined by the number of PCs in both tests. In order to quantify the degree of coordination, the information entropy was calculated and the eigenvalues of the first PC (PC1) were compared between tests. Although no significant differences were found between the tests with respect to the performed maximal workload (Wmax), maximal oxygen consumption (VO2 max), or ventilatory threshold (VT), an increase in the number of PCs and/or a decrease of eigenvalues of PC1 (t = 2.95; p = 0.01; d = 1.08) was found in Test 2 compared to Test 1. Moreover, entropy was significantly higher (Z = 2.33; p = 0.02; d = 1.43) in the last test. In conclusion, despite the fact that no significant differences were observed in the conventionally explored maximal performance and physiological variables (Wmax, VO2 max, and VT) between tests, a reduction of CRC was observed in Test 2. These results emphasize the interest of CRC evaluation in the assessment and interpretation of cardiorespiratory exercise testing

Pupil Dilation Differences When Playing Valorant Under Practice and Competition Conditions: A Case Study

Esports have been growing faster than any other sport in history. Esports are video games that are played in official competitions and usually fall into a major genre, such as fighting games, real-time strategy, multiplayer online battle arena games, or first-person shooters (FPS). Valorant is an FPS. Advances in technology have now made a new class of information, namely biofeedback, readily available. An example of biofeedback is pupil size, which is an indirect measure of the amount of material under active processing and sympathetic/parasympathetic activity. Eye behavior is considered crucial in FPS games. Relevant research is scarce in this specific esport genre. Skills learned during practice should transfer to real-game environments. PURPOSE: To investigate differences in pupil size between practice and competition sessions of Valorant. METHODS: A 21-year-old collegiate esports player, ranked Diamond 1 (top 12%), recorded a practice session and, then, a game of Valorant on the same day. Each session lasted about 65 minutes. Valorant is a 5v5 character-based tactical FPS game. Data was collected via Curia software using LabStreamingLayer to stream data from a Tobii 5L eye tracker into LSL native XDF format, retaining timestamping and synchronization information. Due to having one participant, significance was investigated graphically. RESULTS: On average, the pupil size during practice was 5.1mm and during game 5.3mm. When comparing the mean pupil diameter of both eyes between sessions using violin and scatterplot graphs, it was observed that the distribution of the pupil sizes in the game was shifted higher than during the practice session. CONCLUSION: Our findings indicate higher cognitive load and sympathetic innervation/parasympathetic withdrawal during competition versus practice conditions. Implications for evidence-based practice include replication of load during practice to accomplish game-like conditions, and therefore, facilitate optimal learning and development of expertise. The significance of these findings increases as this form of augmented feedback can be available to the athlete and the coach in real time. Future research should consider examining fixation stability/location, the relationship of pupil dilation with HRV and using longitudinal designs and larger samples

From Exercise Physiology to Network Physiology of Exercise

Exercise physiology (EP) and its main research directions, strongly influenced by reductionism from its origins, have progressively evolved toward Biochemistry, Molecular Biology, Genetics, and OMICS technologies. Although these technologies may be based on dynamic approaches, the dominant research methodology in EP, and recent specialties such as Molecular Exercise Physiology and Integrative Exercise Physiology, keep focused on non-dynamical bottom-up statistical inference techniques. Inspired by the new field of Network Physiology and Complex Systems Science, Network Physiology of Exercise emerges to transform the theoretical assumptions, the research program, and the practical applications of EP, with relevant consequences on health status, exercise, and sport performance. Through an interdisciplinary work with diverse disciplines such as bioinformatics, data science, applied mathematics, statistical physics, complex systems science, and nonlinear dynamics, Network Physiology of Exercise focuses the research efforts on improving the understanding of different exercise-related phenomena studying the nested dynamics of the vertical and horizontal physiological network interactions. After reviewing the EP evolution during the last decades and discussing their main theoretical and methodological limitations from the lens of Complex Networks Science, we explain the potential impact of the emerging field of Network Physiology of Exercise and the most relevant data analysis techniques and evaluation tools used until now

Cardiorespiratory coordination during exercise in adults with Down syndrome

Introduction: Down syndrome (DS) is a chromosomal disorder affecting simultaneously cardiovascular and respiratory systems. There is no research studying the coupling between these systems during cardiorespiratory exercise testing in a population with DS. Cardiorespiratory coordination (CRC), evaluated through principal component analysis (PCA), measures the covariation of cardiorespiratory variables during exercise. Objective: to investigate and compare CRC in adults with and without DS during maximal cardiorespiratory exercise testing. Methods: fifteen adults with DS and 15 adults without disabilities performed a maximal cardiorespiratory exercise test on a treadmill. First, the slope, and afterward the velocity was increased regularly until participants reached exhaustion. The time series of six selected cardiorespiratory variables [ventilation per minute, an expired fraction of O2, the expired fraction of CO2, heart rate, systolic blood pressure (SBP), and diastolic blood pressure (DBP)] were extracted for the analysis. The number of principal components (PCs), the first PC eigenvalues (PC1), and the information entropy were computed for each group (non-DS and DS) and compared using a t-test or a Mann-Whitney U test. Results: two PCs in the non-DS group and three PCs in the DS group captured the variance of the studied cardiorespiratory variables. The formation of an additional PC in the DS group was the result of the shift of SBP and DBP fromthe PC1 cluster of variables. Eigenvalues of PC1 were higher in the non-DS (U = 30; p = 0.02; d = 1.47) than in the DS group, and the entropy measure was higher in the DS compared with the non-DS group (U = 37.5; p = 0.008; d = 0.70). Conclusion: adults with Down syndrome showed higher CRC dimensionality and a higher entropy measure than participants without disabilities. Both findings point toward a lower efficiency of the cardiorespiratory function during exercise in participants with DS. CRC appears as an alternative measure to investigate the cardiorespiratory function and its response to exercise in the DS population

Model no lineal del focus d'atenció durant l'exercici: criteris pel disseny d'estratègies cognitives

[cat] El focus d’atenció durant l’exercici s’ha vingut estudiant durant els darrers anys com a estratègia cognitiva però el seu impacte sobre el rendiment, així com els mecanismes que expliquen el seu efecte ergogènic són encara motiu de controvèrsia. La literatura científica d’aquest camp distingeix principalment 4 categories de pensament: pensaments externs i interns relacionats amb la tasca (TRT-E, TRT-I) i pensaments externs i interns no relacionats amb la tasca (TUT-E, TUT-I; Schomer, 1986). Balagué, Hristovski, Aragonés, i Tenenbaum (2012) van evidenciar que el focus d’atenció no podia considerar-se simplement com una conseqüència de l’activitat volitiva, i van desvetllar un efecte no proporcional del temps d’esforç sobre la dinàmica de pensaments durant un exercici realitzat en cinta rodant fins l’exhauriment. Com a conseqüència d’aquests resultats els autors van proposar un model no lineal del focus d’atenció, que estableix 3 fases de pensament durant l’esforç imposant TUT: una fase inicial estable de TUT, seguida per una fase metaestable (canvis espontanis de TUT a TRT) i finalment, una fase estable de TRT prop de l’exhauriment. Per testar la consistència d’aquest model i aprofundir en la comprensió del rol del focus d’atenció durant l’exercici, els objectius d’aquesta tesi doctoral són: a) testar el model no lineal del focus d’atenció sota diferents protocols d’exercici i de recollida de dades, en diversos tipus de població, b) analitzar la dinàmica del contingut de pensaments, no només respecte a la relació del pensament amb la tasca (TUT/TRT), sinó també respecte a la direcció del seu contingut (intern/extern), i c) establir criteris per a dissenyar estratègies cognitives adequades. Els resultats dels 3 estudis portats a terme van mostrar que es troben les mateixes fases de pensament establertes pel model no lineal del focus d’atenció independentment de la tipologia d’exercici, protocol de recollida de dades, nivell d’entrenament i gènere. Tant la dimensió relació amb la tasca (TUT o TRT) com la direcció (interna o externa) del contingut de pensaments van canviar de forma involuntària en funció de l’esforç acumulat, esdevenint cada cop més associats (TRT) i interns (TRT-I). A l’hora de dissenyar estratègies cognitives, cal tenir en compte que tant els pensaments relacionats com no relacionats amb la tasca poden ser efectius, tot depèn del seu perfil d’estabilitat en cada fase d’esforç. Mentre que a intensitats moderades tant els TUT com els TRT poden ser estables, prop de l’exhauriment només són estables els TRT. Per tant, qualsevol intent de mantenir TUT prop de l’exhauriment podria ser cognitivament exigent i limitar el rendiment.[eng] Attention focus during exercise has been studied during last decades as a cognitive strategy, but the mechanisms underlying its ergogenic effect are still unknown. Growing literature centred around 4 categories of thoughts: external and internal task- related thoughts (TRT-E, TRT-I), and external and internal task-unrelated thoughts (TUT-E, TUT-I; Schomer, 1986). Balagué, Hristovski, Aragonés, and Tenenbaum (2012) showed that attention focus cannot be merely volitional and revealed a non- proportional effect of effort accumulation on thought dynamics, during a constant running until exhaustion. As a result the authors proposed a nonlinear model of attention focus which establishes 3 thought phases while imposing TUT: an initial TUT stable phase, followed by a metastable phase (switches between TUT and TRT), and a stable TRT phase near volitional exhaustion. To contribute to the understanding of the role of attention focus during exercise, the purposes of this thesis are: a) to test the nonlinear model of attention focus under different exercises and data collection methods in different populations, b) to analyse task-relatedness (TUT/TRT) and direction (external/internal) of thought content dynamics, and c) to establish criteria to optimize cognitive strategies. Results of the 3 studies within this thesis showed the same thought phases, regardless of the exercise type, data collection method, gender, and fitness level. Both task-relatedness (TUT, TRT) and direction (external, internal) of thought contents involuntarily changed over accumulated effort and became associative (TRT) and internal (TRT-I). In order to optimize cognitive strategies interventions, practitioners and performers should take into account that both task-related and task-unrelated thoughts can be effective depending on their stability profile. While during low and moderate intensities TUT and TRT are stable, approaching volitional exhaustion TRT is the only stable thought category. Therefore any attempt to keep the focus on thoughts that become predominantly unstable near exhaustion (i.e., TUT), can be cognitively taxing and limit performance

Dynamic networks of physiologic interactions of brain waves and rhythms in muscle activity

The brain plays a central role in facilitating vital body functions and in regulating physiological and organ systems, including the skeleto-muscular and locomotor system. While neural control is essential to synchronize and coordinate activation of various muscle groups and muscle fibers within muscle groups in relation to body movements and distinct physiologic states, the dynamic networks of brain-muscle interactions have not been explored and the complex regulatory mechanism of brain-muscle control remains unknown. Here we present a first study of network interactions between brain waves at different cortical locations and peripheral muscle activity across key physiologic states - wake, sleep and distinct sleep stages. Utilizing a novel approach based on the Network Physiology framework and the concept of time delay stability, we find that for each physiologic state the network of cortico-muscular interactions is characterized by a specific hierarchical organization of network topology and network links strength, where particular brain waves are main mediators of interaction and control of muscular activity. Further, we uncover that with transition from one physiological state to another, the brain-muscle interaction network undergoes marked reorganization in the profile of network links strength, indicating a direct association between network structure and physiological state and function. The pronounced stratification in brain-muscle network characteristics across sleep stages is consistent for chin and leg muscle groups and persists across subjects, indicating a remarkable universality and a previously unrecognized basic physiologic mechanism that regulates muscle activity even during rest and in the absence targeted direct movement. Our findings demonstrate previously unrecognized coordination between brain waves and activation of different muscle fiber types within muscle groups, laws of brain-muscle cross-communication and principles of network integration and control. These investigations demonstrate the potential of network-based biomarkers for classification of distinct physiological states and conditions, for the diagnosis and prognosis of neurodegenerative, movement and sleep disorders, and for developing efficient treatment strategies

Physiological- and performance-related effects of acute olive oil supplementation at moderate exercise intensity

Abstract Background The consumption of olive oil is associated with a diminished risk of cardiovascular disorders and mortality, but the impact of olive oil supplementation on endurance performance is still unclear. Since the beneficial effects of olive oil are observed at a systemic level, its effectiveness may not be precisely measured through the commonly registered maximal and threshold values of some physiological and performance parameters. In contrast, we suggest evaluating it through variables able to capture the coordinated behaviour of physiological systems. Thus, the aim of the current research was to assess the effect of an acute extra virgin olive oil supplementation on cardiorespiratory coordination (CRC) and performance, compared to palm oil. Methods Three separate effort test sessions were carried out separated by 7-day interval. During each session, participants (n = 7) repeated the same progressive and maximal walking test, but under different dietary supplementations in a randomized order: (1) olive oil, (2) palm oil, and (3) placebo. A principal component (PC) analysis of selected cardiovascular and cardiorespiratory variables was carried out to evaluate CRC. Eigenvalues of the first PC (PC1) and the loadings of the cardiorespiratory variables onto PC1 were compared among dietary supplementations. In order to more accurately evaluate CRC, all the tests were divided into 3 equal sections, corresponding to low, moderate, and high exercise intensities, and the aforementioned procedure was repeated for each section in all the tests. Results Statistically significant differences were observed regarding PC1 eigenvalues among dietary supplementations (χ 2 (8,2) = 6.3; p = .04), only at moderate intensity exercise. Specifically, PC1 eigenvalues were higher under olive oil compared to palm oil (2.63 ± 0.51 vs. 2.30 ± 0.28; Z = 2.03; p = .04; d = 0.80) and placebo supplementations (2.63 ± 0.51 vs. 2.38 ± 0.36; Z = 2.20; p = .03; d = 0.57). Conclusions Supplementation with extra virgin olive oil increased CRC during a progressive walking test at moderate intensity, although did not change performance and other physiological markers. CRC analysis appears as a sensitive tool to investigate the physiological and performance effects of dietary supplementations

AGE-RELATED BREAKDOWN OF CARDIO-MUSCULAR COORDINATION

BACKGROUND: The heart coordinates with skeletal muscles to facilitate movement, maintain cardiovascular homeostasis, and adapt to exercise. However, the precise mechanisms through which autonomic control of heart rate variability facilitates coordination with distinct muscles have yet to be elucidated, especially in the context of aging. Here we investigate the temporal evolution of cardio-muscular coordination during a maximal squat test, with specific focus on comparing young and older adults. METHODS: Thirty young and ten older adults performed one maximal body weight squat test until exhaustion. During the protocol, simultaneous recordings were taken of a 3-lead electrocardiogram (EKG Lead II) along with electromyography (EMG) signals from the following leg and back muscles: left and right vastus lateralis, and left and right erector spinae. We first obtained instantaneous heart rate (IHR, representing heart rate variability) derived from the EKG signal (Pan-Tomkins QRS detection), and decompose the EMG recordings in ten frequency bands [F1-F10], representing distinct muscle fiber types. We next quantified pair-wise coupling (cross-correlation C; amplitude-amplitude coupling) between the time series for IHR and all EMG spectral power frequency bands in each leg/back muscle. RESULTS: Young adults showed a stronger level of cardio-muscular coordination between the heart and all leg and back muscles. Specifically, low [F1-F5] EMG frequency bands, associated with type-I slow muscle fibers, exhibited stronger coupling with IHR (CMEAN = 0.35: SD = 0.03) compared to intermediate/fast frequency [F6-F10] EMG bands (CMEAN = 0.20: SD = 0.02). In contrast, older adults showed an overall significant decline in coupling strength between IHR and all EMG frequency bands (CMEAN = 0.05: SD = 0.02) compared to young adults (p \u3c 0.001). CONCLUSION: The pronounced break-down in cardio-muscular coordination in older adults may be attributed to the age-related deterioration of heart rate variability, resulting from impaired autonomic nervous system function and reduced cardiac flexibility. Understanding the mechanisms underlying the decline in cardio-muscular coordination during exercise is crucial for developing strategies to counteract the effects of aging. This dynamic network approach can lead to the development of novel network-based markers to assess the impact of aging on cardiac and neuro-muscular function