Preface

Exercise physiology is one of the most researched sports sciences, with extensive practical applications ranging from sports performance to health and well-being. *Exercise Physiology* brings together emerging research in this area, as well as exploring future perspectives. The book is divided into three fundamental sections: (i) Exercise, Brain and Cognitive Functioning; (ii) Energy and Human Performance; and (iii) Physical Exercise and Immune Response.

The first section, "Exercise, Brain and Cognitive Functioning" links exercise physiology to the brain and cognitive functioning.

The chapter "The Performance during the Exercise: Legitimizing the Psychophysiological Approach" looks at the existing evidence and new perspectives on the role of the brain as a central regulator of performance, questioning the complex interdependencies and interrelations between fatigue and physical exercise from a psychophysiological perspective, and bringing together concepts such as pacing behavior, decision-making, self-regulation of effort, prior knowledge of the duration of the task, and perception of effort. Sleep is extremely important for numerous biological functions, and sleep deprivation can have significant effects on athletic performance in the short, medium, and long term.

The chapter "The Importance of Sleep in Athletes" explores sleep as an essential component in athletes' recovery from fatigue, mainly due to its restorative physiological and psychological effects. Monitoring athletes' sleep patterns can optimize recovery strategies, health, performance, fitness, and fatigue status. The authors discuss the following training- and competition-related factors: 1) sleep patterns and disorders; (2) sleep and optimal functioning; (3) screening, tracking, and assessment of sleep; and (4) sleep interventions (i.e., sleep hygiene).

The chapter "Physiological Adaptions to Acute Hypoxia" describes the main types of hypoxia in the oxygen cascade, as well as the physiological consequences of acute hypoxia for training and health. Tissue hypoxia can be caused by any obstacle in the oxygen cascade, and by hypoxaemia, anaemia, stagnation, and histotoxic hypoxia.

"Potential of Physical Activity-Based Intervention on Sleep in Children with and without Autism Spectrum Disorder" also addresses the topic of sleep quality, but from a more clinical perspective, reporting on sleep disorders in children with autism spectrum disorder (ASD). Physical activity is described in the literature as an optimal non-pharmacological approach for improving sleep. The research presented in this chapter studied 75 children, 57 of whom had ASD, with 18 who had typical development as a control. The subjects wore an accelerometer monitor (Sense Wear® Pro Armband 3, Body media) for six consecutive days and nights to assess their sleep and physical activity. Moderate to vigorous physical activity has been shown to be effective in improving sleep in children both with and without ASD. The chapter concludes with recommendations for improving sleep quality and reducing sedentary behavior in both children with ASD and children in general. Physical inactivity and stress at work have been linked to the sedentary lifestyles

and lack of time commonly observed today. With market demand for bioactive compounds that mimic or potentiate the effects of exercise, exercise mimetics has emerged as a controversial topic in sports and exercise physiology. While this idea is attractive for those seeking quick results while avoiding the need for a lot of exercise, it is controversial due to the complexity of the molecular and physiological mechanisms involved.

The chapter "Mechanical Limits of Cardiac Output at Maximal Aerobic Exercise" discusses the factors that limit the maximum aerobic exercise by maximal oxygen uptake (VO2max). Cardiac output is the dominant determinant of VO2, so the improvement in VO2max depends largely on the increase of the return function and the effect of muscle contractions. Stroke volume is a key determinant of maximum cardiac output and therefore has extensive implications for peak performance. Significant academic attention has been paid in recent years to the physiological processes associated with altitude training, and to the role of exercise in the clinical

The third and final section, "Physical Exercise and Immune Response", explores the immune response to physical activity and exercise in a clinical perspective. Exercise training and regular physical activity have been suggested as non-pharmacological approaches to improving breast cancer outcomes. Research reports improvements in cardiorespiratory fitness levels, the completion rate of pharmacological therapies, reduction of cancer-related fatigue, and the improvement of muscle strength and quality of life as among the positive interdependencies between exercise train-

The chapter "Exercise Training in the Spectrum of Breast Cancer" reports the effects of exercise on the regulation of metabolic and steroid hormones, tumourrelated inflammation, and the attenuation of cancer-induced muscle wasting, highlighting exercise designs that can trigger the best outcomes. According to the authors, it is difficult to identify, among diverse exercise protocols, those that produce the most effective outcomes for breast cancer patients. However, a combination of moderate to vigorous aerobic and resistance exercise appears to promote

The final chapter "Physical Activity and Vaccine Response" discusses the effect of exercise on vaccine response. The study summarizes the current understanding of

We, therefore, invite readers to discover the most recent publications, research, and

**Ricardo Ferraz, Henrique Neiva and Daniel A. Marinho**

Department of Sports Sciences, University of Beira Interior,

**José E. Teixeira and Pedro Forte**

Instituto Politécnico de Bragança,

Departamento de Desporto e Educação Física,

Higher Institute of Educational Sciences of the Douro,

Covilhã, Portugal

Bragança, Portugal

**Luís Branquinho**

Porto, Portugal

theoretical frameworks in the fundamental area of Exercise Physiology.

conditions leading to hypoxia.

the best results.

ing and breast tumour clinical outcomes.

exercise and antibody production.

The chapter "Exercise Mimetics: An Emerging and Controversial Topic in Sport and Exercise Physiology" explains the challenges of designing a pill that can reliably provide the myriad and complex adaptations afforded by exercise training, with a focus on skeletal muscle. The multifaceted human physiological response to exercise, with its inherent redundancy, may mean weight-loss pills are no more than a utopia. Moreover, exercise promoting human health should adhere to evidencebased guidelines and pharmaceutical interventions.

The second section, "Energy and Human Performance", reports the physiological assumptions of energy production in human performance.

The chapter "Methodological Procedures for Non-Linear Analyses of Physiological and Behavioural Data in Football" summarizes the main methods of extracting positional data using non-linear analyses such as entropy scales, relative phase transforms non-linear indices, cross-correlation, fractals, and clustering methods. A football match is a complex and dynamic system with emergent behavior, selfsimilarity, self-organization and a chaotic component. Physiological and behavioral football data should therefore be integrated to determine the complexity and nonlinearity of the system.

The chapter "Justification of some Aspects of the Choice of Training Means Selection in Track-and-Field Jumps" establishes that the take-off in track-and-field jump training exercises uses relatively independent biomechanics (BM), similar to competitive jumping. A study of the underlying biomechanics and physiological processes can improve technique development choices. Four types of take-off training are identified, each with specific features: (i) involving the BM of legs (take-off leg) and body extension; (ii) involving the swinging links BM; (iii) involving the "overturned pendulum" BM; and (iv) involving the swinging links BM combined with the "overturned pendulum" BM.

"From Exercise Physiology to Network Physiology of Exercise" presents new insights into Exercise Physiology based on Molecular Exercise Physiology and Integrative Exercise Physiology. Inspired by the new field of Network Physiology and Complex Systems Science, Network Physiology of Exercise, the dynamics of the vertical and horizontal physiological network interactions were explored in new theoretical assumptions, research programs, and the practical applications of Exercise Physiology.

"Energy Cost of Walking and Running" examines walking and running as a basic way of influencing an individual's condition, health, and fitness. Speed of movement and the energy cost (EC) of applied physical activities can be measured in the laboratory and in the field, enabling movement training to be speeded up. The total EC needs to exceed the so-called stimulus threshold, that is, the subject of physical training must reach a certain minimum level of total EC of applied physical training. Assessing the energy intensity and cost can significantly contribute to reducing fatigue and the incidence of injury, and to increasing physical fitness.

The chapter "Mechanical Limits of Cardiac Output at Maximal Aerobic Exercise" discusses the factors that limit the maximum aerobic exercise by maximal oxygen uptake (VO2max). Cardiac output is the dominant determinant of VO2, so the improvement in VO2max depends largely on the increase of the return function and the effect of muscle contractions. Stroke volume is a key determinant of maximum cardiac output and therefore has extensive implications for peak performance. Significant academic attention has been paid in recent years to the physiological processes associated with altitude training, and to the role of exercise in the clinical conditions leading to hypoxia.

The third and final section, "Physical Exercise and Immune Response", explores the immune response to physical activity and exercise in a clinical perspective. Exercise training and regular physical activity have been suggested as non-pharmacological approaches to improving breast cancer outcomes. Research reports improvements in cardiorespiratory fitness levels, the completion rate of pharmacological therapies, reduction of cancer-related fatigue, and the improvement of muscle strength and quality of life as among the positive interdependencies between exercise training and breast tumour clinical outcomes.

The chapter "Exercise Training in the Spectrum of Breast Cancer" reports the effects of exercise on the regulation of metabolic and steroid hormones, tumourrelated inflammation, and the attenuation of cancer-induced muscle wasting, highlighting exercise designs that can trigger the best outcomes. According to the authors, it is difficult to identify, among diverse exercise protocols, those that produce the most effective outcomes for breast cancer patients. However, a combination of moderate to vigorous aerobic and resistance exercise appears to promote the best results.

The final chapter "Physical Activity and Vaccine Response" discusses the effect of exercise on vaccine response. The study summarizes the current understanding of exercise and antibody production.

We, therefore, invite readers to discover the most recent publications, research, and theoretical frameworks in the fundamental area of Exercise Physiology.

> **Ricardo Ferraz, Henrique Neiva and Daniel A. Marinho** Department of Sports Sciences, University of Beira Interior, Covilhã, Portugal

#### **José E. Teixeira and Pedro Forte**

Departamento de Desporto e Educação Física, Instituto Politécnico de Bragança, Bragança, Portugal

**Luís Branquinho**

Higher Institute of Educational Sciences of the Douro, Porto, Portugal

Section 1
