Investigation of Complexity and regulatory role of physiological activities during a pacing exercise

Existing physiological control fatigue models propose that there may be a regulator in the central nervous system which modulates our daily physical activity. Within limits, this regulator ensures physical activity is completed without physiological system failure through interactive communications between the peripheral systems and the central systems. The ability of the central nervous system to regulate exercise is vital to optimise sport performance when severe intensity exercise might be required for prolonged or frequent periods. Based on mathematical models, this investigation explores the complex relationship between some of the mechanisms controlling physical activity and behaviour. In order to analyse the system control mechanisms, heart rate, volume of oxygen consumption and power output were measured for ten well-trained male cyclists. Using power spectrum analysis, fractal analysis, recurrence quantification techniques and continuous wavelet transforms, we show that the system control mechanisms regulating physiological systems, have distinct complexity. Moreover, the potential central controller uses specific frequency bands simultaneously to control and communicate with the various physiological systems. We show that pacing trials are regulated by different physiological systems

The Influence of Collective Behaviour on Pacing in Endurance Competitions

A number of theoretical models have been proposed to explain pacing strategies in individual competitive endurance events. These have typically related to internal regulatory processes informing the making of decisions relating to muscular work rate. Despite a substantial body of research investigating the influence of collective group dynamics on individual behaviours in various animal species, this issue has not been comprehensively studied in individual athletic events. This is surprising given that athletes directly compete in close proximity to one another, and that collective behaviour has also been observed in other human environments. Whilst reasons for adopting collective behaviour are not fully understood, it is thought to result from individual agents following simple local rules resulting in seemingly complex large systems acting to confer some biological advantage to the collective as a whole. Although such collective behaviours may generally be beneficial, endurance events are complicated by the fact that increasing levels of physiological disruption as activity progresses may compromise the ability of individuals to continue to interact with other group members. This could result in early fatigue and relative underperformance due to suboptimal utilisation of physiological resources by some athletes. Alternatively, engagement with a collective behaviour may benefit all due to a reduction in the complexity of decisions to be made and a subsequent reduction in cognitive loading and mental fatigue. This paper seeks evidence for collective behaviour in previously published analyses of pacing behaviour and proposes mechanisms through which it could potentially be either beneficial, or detrimental to individual performance

The effects of fatigue and task knowledge duration on kicking performance and pacing strategies in soccer

Interest in the topic of fatigue in sports science has a long history and recent research and theories have highlighted the problem of fatigue more broadly. A new perspective seems to have emerged supported by the concept of the brain acting as a central master regulator of exercise performance. This kind of regulation is named “pacing” and nowadays is assumed as an important concept in sport and exercise, supporting this psychophysiological perspective. Having prior knowledge about the activity is a central point on this view of pacing, based on the principle that athletes are then able to self-regulate their own performance through the entirety of the exercise. However, the precise importance of the psychophysiological perspective in context of training (exercises) or competition remains unclear, especially in team sports as a soccer. The general aim of this thesis was to analyze the effects of fatigue and task knowledge duration on kicking performance and pacing strategies in soccer. For the accomplishment of these purposes the following sequence was used: (i) reviewing the available literature; (ii) demonstrating the effects of fatigue on kicking ball velocity in soccer players; (iii) investigating the influence of fatigue upon kicking performance of soccer players and examining the effect of the knowledge of the exercise duration upon these two parameters; (iv) investigating the influence of different exercise intensities on kicking accuracy and velocity in soccer players and analyzing the player pacing strategies from different prescribed intensities; (v) investigating the possible influence of knowledge of exercise duration on player pacing strategies during soccer small-sided games (5 vs 5). The main conclusions drawn were (i) there is potential negative fatigue effect induced by high intensity exercises on kicked-ball velocities in soccer; (ii) the effect of fatigue can be variable; (iii) kicking accuracy is not affected by fatigue considering the accuracy as a secondary aim in relation with kicking velocity; (iv) no effects of knowledge of the exercise duration were found on kicking performance, but in respect of pacing strategies during soccer small-sided games, the findings showed its relevance. In addition, the results support the hypothesis about the involvement of psychophysiological factors and they express the complexity of the fatigue phenomenon and the relevance of the theory of central master regulation of the brain on exercise performance

Optimising activity pacing to promote a physically active lifestyle in medical settings: A narrative review informed by clinical and sports pacing research

Regular exercise can improve wellbeing, yet data are scarce on how persons with disabling conditions may benefit from active lifestyles, due to the complexities of exercise prescription in this population. A novel medical concept for exercise prescription called activity pacing is the subject of this review, which identifies the potential for this strategy to optimally integrate existing medical and sports medicine approaches in promoting physical activity in persons with disabling conditions. Activity pacing is a goal-directed behavioural process of empowering people to confidently develop decision-making and planning over how and where to distribute available energy across daily activities. Currently, different conceptual traditions and definitions of pacing exist with important implications for the implementation and subsequent effectiveness of activity pacing. Application of activity pacing has mostly focused on symptom-reduction to improve self-regulatory behaviour, and less on physical activity stimulation for health and wellbeing. Further studies and greater connection between medical and sports science research are needed on how to adapt, tailor and optimise activity pacing to make it successful. The potential of activity pacing to increase physical activity and lessen fatigue could be a powerful tool to help fight the growing incidence of physical inactivity, particularly in persons with disabling conditions

Deception studies manipulating centrally acting performance modifiers: a review.

Athletes anticipatorily set and continuously adjust pacing strategies before and during events to produce optimal performance. Selfregulation ensures maximal effort is exerted in correspondence with the end point of exercise, while preventing physiological changes that are detrimental and disruptive to homeostatic control. The integration of feedforward and feedback information, together with the proposed brain_s performance modifiers is said to be fundamental to this anticipatory and continuous regulation of exercise. The manipulation of central, regulatory internal and external stimuli has been a key focus within deception research, attempting to influence the self-regulation of exercise and induce improvements in performance. Methods of manipulating performance modifiers such as unknown task end point, deceived duration or intensity feedback, self-belief, or previous experience create a challenge within research, as although they contextualize theoretical propositions, there are few ecological and practical approaches which integrate theory with practice. In addition, the different methods and measures demonstrated in manipulation studies have produced inconsistent results. This review examines and critically evaluates the current methods of how specific centrally controlled performance modifiers have been manipulated, within previous deception studies. From the 31 studies reviewed, 10 reported positive effects on performance, encouraging future investigations to explore the mechanisms responsible for influencing pacing and consequently how deceptive approaches can further facilitate performance. The review acts to discuss the use of expectation manipulation not only to examine which methods of deception are successful in facilitating performance but also to understand further the key components used in the regulation of exercise and performance

Multiple System Modelling and Analysis of Physiological and Brain Activity and Performance at Rest and During Exercise

One of the current interests of exercise physiologists is to understand the nature and control of fatigue related to physical activity to optimise athletic performance. Therefore, this research focuses on the mathematical modelling and analysis of the energy system pathways and the system control mechanisms to investigate the various human metabolic processes involved both at rest and during exercise. The first case study showed that the PCr utilisation was the highest energy contributor during sprint running, and the rate of ATP production for each anaerobic subsystem was similar for each athlete. The second study showed that the energy expenditure derived from the aerobic and anaerobic processes for different types of pacing were significantly different. The third study demonstrated the presence of the control mechanisms, and their characteristics as well as complexity differed significantly for any physiological organ system. The fourth study showed that the control mechanisms manifest themselves in specific ranges of frequency bands, and these influence athletic performance. The final study demonstrated a significant difference in both reaction time and accuracy of the responses to visual cues between the control and exercise-involved cognitive trials. Moreover, the difference in the EEG power ratio at specific regions of the brain; the difference in the ERP components’ amplitudes and latencies; and the difference in entropy of the EEG signals represented the physiological factors in explaining the poor cognitive performance of the participants following an exhaustive exercise bout. Therefore, by using mathematical modelling and analysis of the energy system pathways and the system control mechanisms responsible for homeostasis, this research has expanded the knowledge how performance is regulated during physical activity and together with the support of the existing biological control theories to explain the development of fatigue during physical activity

Nutrition Strategies for Triathlon

Contemporary sports nutrition guidelines recommend that each athlete develop a personalised, periodised and practical approach to eating that allows him or her to train hard, recover and adapt optimally, stay free of illness and injury and compete at their best at peak races. Competitive triathletes undertake a heavy training programme to prepare for three different sports while undertaking races varying in duration from 20 min to 10 h. The everyday diet should be adequate in energy availability, provide CHO in varying amounts and timing around workouts according to the benefits of training with low or high CHO availability and spread high-quality protein over the day to maximise the adaptive response to each session. Race nutrition requires a targeted and well-practised plan that maintains fuel and hydration goals over the duration of the specific event, according to the opportunities provided by the race and other challenges, such as a hot environment. Supplements and sports foods can make a small contribution to a sports nutrition plan, when medical supplements are used under supervision to prevent/treat nutrient deficiencies (e.g. iron or vitamin D) or when sports foods provide a convenient source of nutrients when it is impractical to eat whole foods. Finally, a few evidence-based performance supplements may contribute to optimal race performance when used according to best practice protocols to suit the triathlete’s goals and individual responsiveness