Resilience and sport: Neurophysiology and readiness, rather than mental toughness and grit
Finding ways in which athletes can be ready for the demands of sport training and competition is paramount for success. The scope of this summary will clarify the importance of why we need to depart from concepts of ‘mental toughness’ and ‘grit’ and, instead, focus on understanding neurophysiology and readiness to create opportunities for managing athlete health and performance throughout cycles of training and competition.
The Illusion of Mental Toughness and Grit
Although mental toughness (MT) and grit are ‘familiar’ or accessible terms, these concepts are considered to reflect modest and unfounded science. Neither concept considers our innate wiring to adapt and survive (which is, in effect, our true innate toughness), and as such they ignore neurophysiology which is a well-defined science in this area. In particular, we are wired to survive, as per evolutionary dynamics, which relies on a process of stimulation and rest. This means that individuals can be trained to be ready, resilient, and adaptive through proper dosing and timing of both training and rest — importantly, these scientific principles are not adequately addressed by MT or grit. [1,2,3] MT has been correlated with healthy sleep schedules and quality of life demonstrating evidence of our neurophysiology underpinnings of readiness, resiliency, adaption, and hormesis rather than a subjective state of toughness or grit. [4,5]
Specifically, both MT and grit are, effectively, subjective concepts because that is primarily the nature of information from which they are derived. Examples of this include observation or information obtained by participants/subjects after the experience — and, while this in itself is not unfounded, it provides only a modest type of data and should be cautiously interpreted. [6,7,8,9,10] While we can use subjective data, it should not be solely relied upon or interpreted beyond what we can verify; however, this has unfortunately been the case for both terms. That is, because MT and grit ‘seem real’ and have the illusion of validity, that illusion is fueled by belief bias (meaning we want to desperately believe that the multifactorial process of performance is very simple); and, as such, these concepts have seemingly become factual without sufficient scientific proof. [11,12,13]
Both MT and grit have failed to be proven as scientific concepts even though these phenomena have been studied for decades. Overall, investigations of MT and grit have largely been based on inadequacies related to research design, statistical analysis and interpretation, and lack of transferability/generalizability. [14,15,16,17]
Paradoxically, this has led to the two terms being defined by nothing and everything, which is another clear indicator of these notions representing poor scientific concepts. Beyond the concerns related to hyperbole, when we reduce complex concepts associated with high performance to simple terms, this in turn detracts from placing our focus on appropriate factors related to health and long-term athletic development. [18,19]
A key established factor associated with health and long-term athletic development is resilience. Resilience is defined as a process of adapting well in the face of adversity, trauma, tragedy, threats or significant sources of stress.  Research has shown that resilience is ordinary, not extraordinary.  Being resilient does not mean that a person doesn’t have trouble or distress. Emotional pain and sadness are common in people who have suffered major adversity or trauma in their lives. In fact, the road to resilience is likely to involve considerable emotional distress, and that can serve as both a signal to move toward resilience, as well as being a vital contributor to the process of adaption and evolution. 
Resilience is not a trait that people either have or do not have. It involves behaviors, thoughts and actions that can be learned and developed in anyone. This concept first appeared in the psychological literature via the examination of trauma and assessment of individuals exposed to traumatic situations who did not show signs of acute stress with respect to post-traumatic stress disorder. [23,24,25,26,27] For example, affected individuals included those who endured abuse, neglect, oppressive governmental regimes, regions of conflict, and occupational trauma (such as firefighters, police, paramedics/medical personnel, and warfighters). [28, 29, 30]
The early studies — and still many today — have typically focused on two factors; i.e., cultural/social support and personality as ‘immune responses’ or ways to deal with the world, and the extent to which interpersonal/intrapersonal coping leads to buffering of chronic stress. [31,32,33] These approaches initially shed light on understanding resilience via psychometrics, and the concept of resilience became increasingly more objective via the integration of neurophysiology and neurometrics (e.g., brain imaging, electroencephalogram (EEG), and neuropeptides).
For example, examinations of neurophysiology has brought to light how neuropeptide Y (NPY) and 5-Dehydroepiandrosterone (5-DHEA) are thought to limit the stress response by reducing sympathetic nervous system activation and protecting the brain from the potentially harmful effects of chronically elevated cortisol levels respectively. In addition, the relationship between social support and stress resilience is thought to be mediated by the oxytocin system’s impact on the hypothalamic-pituitary-adrenal axis.
Neurometrics have further allowed us to pinpoint a brain region called the ventromedial prefrontal cortex (VmPFC) which appears to be implicated in depression, alcohol addiction and post-traumatic stress disorder, among several other maladaptive coping behaviors.  Dynamic stress mobilizes the VmPFC, and in turn it mediates our stress response, resulting in the softening and management of neurological, physiological and behavioral reactions to traumatic experiences. To be clear, sport is trauma because of the demands it places on athletes regarding their training, competition, travel, and interpersonal needs.
Importantly, individuals/athletes reflect human variation with respect to neuroflexibility or neuroplasticity of the VmPFC. Recent, research has focused on the notion that neuroflexibility of the VmPFC, may be a major determinant of a person’s resilience and capacity to cope with stress and engage the parasympathetic nervous system. 
Thus, investigations of resilience moved from purely an examination of information after-the-fact, to evaluations in real-time or critical periods of time — these latter assessments are also known as ‘windows of opportunity’ and enable us to optimally train and understand adaption to stress. Further, examining both subjective and objective data allows training to be fully comprehended and, thus, increases our precision of dosing stress properly (re: Hormetic Dosing) and teaching neuropsychological skills to enhance the buffering of stress. [38,39,40,41,42,43]
Dosing matters for the desired outcome — Hormesis
Hormesis is particularly important in the context of resilience as how we apply dosed stress in the form of training will have a significant impact on adaption and growth. The basic purpose of hormesis is maintaining health, a condition of homeostasis across the entire human functional system and driven by the central nervous system (CNS). The principles of Hormesis and Homeostasis are one of the most important characteristics of all living things is the ability to maintain a (reasonably) constant internal environment of stimulation and adaption. This ability is known as homeostasis. [44,45]
Homeostasis is not a static state; rather it is a dynamic process of constant changes and adjustments. Hormesis acknowledges dosing of the functional system must remain with ranges that it can adapt with. Thus, a hormetic response to a challenge not only maintains a functional internal environment but also improves it over time.
Hormesis applies within a sport context as the challenge is to properly stimulate athletes via training and then have them return to homeostasis where growth and adaption happens. Even more challenging is the world of sport has ever-changing conditions within training and even more broadly when considering an athlete’s life in general. [46,47]
Hormetic patterns are further demonstrated in sport when the demands of training are dosed beyond the range in which the functional system cannot adapt, meaning homeostasis is not fully consolidated. When dosed improperly in sport training it leads to staleness, burnout, underperformance, over-stretching, and over-training. Hormetic responses represents an CNS derived warning system of proper adaption or an overcompensation leading to a disruption in homeostasis. [48,49, 50, 51]
Resilience is ultimately defined by neurophysiology and physiology, and thereby reflects a sequence of events that begins with readiness, then leads to resilience and, eventually, adaptation (Figure 3).
Bringing it all together: The brain as the driver of health and performance
Noting the established evidence base for resilience and readiness (and the contrasting lack of evidence for MT and grit), we will briefly turn to the overall driver of these activities — i.e., the brain. This organ is central to adaptation vis-à-vis experiences, and this process includes stressors that are capable of both changing brain structure and altering its systemic functions. Because the brain is the master regulator of all systems and behavior, alterations in brain function by way of chronic stress have direct and indirect effects on cumulative overload (the cost of adaptation and downgrade of readiness-resilience-adaptation).
The healthy brain has considerable capacity for resilience, and that is based upon its ability to respond to interventions designed to open ‘windows of plasticity’ and ‘windows of trainability’, and to ultimately redirect its function toward better health. Thus, it is critical that facilitation of plasticity be allotted for as a means to develop and enhance brain health as this will, in turn, lead to increased physical, emotional, and cognitive capacity for athlete development and performance. In sum, resilience is based upon brain health which is an active process of rest and recovery that targets neural-growth and neural-management, and stress is therefore redirected as a stimulus for growth rather than development of a chronic injury.
About the Author
Dr. John Sullivan is a Sport Scientist and Clinical Sport Psychologist with over twenty years of clinical and scholarly experience.
He has held appointments within the National Football League (NFL), English Premier League (EPL), the NCAA (Providence College, University of Rhode Island, Brown University), and the elite military and law enforcement in North America.
Dr. Sullivan is also a visiting scholar and sport scientist at the Queensland Academy of Sport and Queensland University of Technology in Brisbane, Australia.
He has established expertise as national and international practitioner-researcher who conducts central nervous system (CNS) measurement/assessment, performance optimization, and concussion assessment/rehabilitation.
He is a frequent contributor writing on sport science and sports medicine and his latest efforts have focused on a series of books which distills the latest performance psychology, cognitive science, and neuroscience, related to optimal brain performance and health entitled The Brain Always Wins.
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