Current Aspects of Selected Factors to Modulate Brain Health and Sports Performance in Athletes

s review offers a comprehensive evaluation of current aspects related to nutritional strategies, brain modulation, and muscle recovery, focusing on their applications and the underlying mechanisms of physiological adaptation for promoting a healthy brain, not only in athletes but also for recreationally active and inactive individuals. We propose that applying the rule, among others, of good sleep, regular exercise, and a properly balanced diet, de ned as “SPARKS”, will have a bene cial effect on the function and regeneration processes of the gut–brain–muscle axis. However, adopting the formula, among others, of poor sleep, stress, overtraining, and dysbiosis, de ned as “SMOULDER”, will have a detrimental impact on the function of this axis and consequently on human health as well as on athletes. Understanding these dynamics is crucial for optimizing brain health and cognitive function. This review highlights the signi cance of these factors for overall well-being, suggesting that adopting the “SPARKS” approach may bene t not only athletes but also older adults and individuals with health conditions. Keywords:stress; supplements; sports performance; brain

and consequently on human health as well as on athletes. Understanding these dynamics is crucial for optimizing brain health and cognitive function. This review highlights the signi cance of these factors for overall well-being, suggesting that adopting the “SPARKS” approach may bene t not only athletes but also older adults and individuals with health conditions. Keywords:stress; supplements; sports performance; brain and muscle regeneration 1. Introduction Post-exercise recovery is of the utmost importance for athletes. Effectively managing the equilibrium between training stress and recovery is essential to optimizing adaptation and performance during training as well as the competition period [1]. The physiological and psychological demands of a competitive season may present signi cant challenges to athletes. Consequently, athletes should balance stress and recovery, employing various techniques to effectively manage fatigue and improve overall recovery and performance in subsequent training sessions and competitions. It is widely recognized that sports performance is a comprehensive and multifaceted process that involves the musculoskeletal system as well as the central nervous system (CNS) and the peripheral nervous system (PNS) [2]. Changes in the CNS and motor unit recruitment are widely believed to be directly linked to fatigue, resulting in declines in both physical and mental performance [3]. Physical fatigue can be attributed to various factors, including muscle damage, glycogen depletion, dehydration, and mental fatigue [3]. Therefore, this is an appropriate time to summarize our current knowledge about nutritional strategies, brain modulation, and muscle recovery, highlighting their applications and the underlying mechanisms of physiological adaptation for fostering brain health in both athletes and non-athletes. This review presents recent advancements in selected nutrition strategies, brain modu- lation, and muscle recovery, with a focus on promoting brain health in competitive athletes and individuals with different activity levels. A comprehensive bibliographic search was Nutrients2024,16, 1842.

Nutrients2024,16, 1842 2 of 27 conducted in PubMed to identify pertinent articles and experimental evidence, offering readers a thorough analysis of the subject matter. Athletes face signi cant stress due to the nature of their training, which includes both high-intensity intermittent activity and prolonged exercises, leading to considerable physiological and neuromuscular stress [4]. While stress is crucial for physiological adapta- tion and performance enhancement [5], chronic stress can worsen in ammation, disrupt homeostasis, and impair muscle function and sports performance. The skeletal muscle, abundant in the human body, not only facilitates movement but also regulates systemic metabolic balance and in uences responses throughout the organism by releasing signaling factors [6]. Therefore, muscle contraction may affect many tissues and organs. Emerging evidence suggests that the CNS is also subject to signaling initiated by muscles [6], a topic we will delve into further in this review. Moreover, there is an assumption that a gut–brain–muscle axis exists and plays a signi cant role in maintaining not only physical but also mental health, which is crucial not only for athletes. Hence, proper nutrition and organism recovery strategies are essential to maintain the optimal function of this axis. By exploring the interplay between nutrition strategies, brain modulation techniques, and muscle recovery, valuable insights may be gained to promote overall brain health and cognitive function, thus enhancing sports performance. This review offers a thorough evaluation of nutritional strategies, brain modulation, and muscle recovery, focusing on promoting a healthy brain in competitive athletes and individuals with varying activity levels. By exploring their applications and underlying physiological mechanisms, it sheds light on the importance of considering speci c factors to foster a healthy brain and enhance cognitive function. Athletes are exposed to several negative external and internal factors that may disrupt sports performance and recovery processes. A cascade of negative events associated with chronic stress can initiate overtrain- ing and sleep disorders, resulting in mood changes. Poorly balanced nutrition may lead to dietary neglect, causing dysbiosis, with increased in ammatory and oxidative stress that affects many tissues and organs, directly increasing the risk of injury or infection (SMOULDER).

that may disrupt sports performance and recovery processes. A cascade of negative events associated with chronic stress can initiate overtrain- ing and sleep disorders, resulting in mood changes. Poorly balanced nutrition may lead to dietary neglect, causing dysbiosis, with increased in ammatory and oxidative stress that affects many tissues and organs, directly increasing the risk of injury or infection (SMOULDER). To prevent the negative effects of chronic stress, elements described by the acronym SPARKS should be routinely implemented as preventive measures. These mea- sures encompass both psychological-cognitive aspects (quantity and quality of sleep and post-workout recovery) and ensuring proper bodily functions, including a balanced diet rich in probiotics, antioxidants, and supplements to improve the physiological function of not only athletes. We advocate for adhering to the “SPARKS” rule for bene cial outcomes, contrasting it with the detrimental effects of embracing the “SMOULDER” formula (see Figure).Nutrients 2024, 16, 1842 2 of 29 athletes and individuals with different activity levels. A comprehensive bibliographic search was conducted in PubMed to identify pertinent articles and experimental evidence, offering readers a thorough analysis of the subject matter. Athletes face significant stress due to the nature of their training, which includes both high-intensity intermittent activity and prolonged exercises, leading to considerable physiological and neuromuscular stress [4]. While stress is crucial for physiological adaptation and performance enhancement [5], chronic stress can worsen inflammation, disrupt homeostasis, and impair muscle function and sports performance. The skeletal muscle, abundant in the human body, not only facilitates movement but also regulates systemic metabolic balance and influences responses throughout the organism by releasing signaling factors [6]. Therefore, muscle contraction may affect many tissues and organs. Emerging evidence suggests that the CNS is also subject to signaling initiated by muscles [6], a topic we will delve into further in this review. Moreover, there is an assumption that a gut–brain–muscle axis exists and plays a significant role in maintaining not only physical but also mental health, which is crucial not only for athletes. Hence, proper nutrition and organism recovery strategies are essential to maintain the optimal function of this axis. By exploring the interplay

we will delve into further in this review. Moreover, there is an assumption that a gut–brain–muscle axis exists and plays a significant role in maintaining not only physical but also mental health, which is crucial not only for athletes. Hence, proper nutrition and organism recovery strategies are essential to maintain the optimal function of this axis. By exploring the interplay between nutrition strategies, brain modulation techniques, and muscle recovery, valuable insights may be gained to promote overall brain health and cognitive function, thus enhancing sports performance. This review offers a thorough evaluation of nutritional strategies, brain modulation, and muscle recovery, focusing on promoting a healthy brain in competitive athletes and individuals with varying activity levels. By exploring their applications and underlying physiological mechanisms, it sheds light on the importance of considering specific factors to foster a healthy brain and enhance cognitive function. Athletes are exposed to several negative external and internal factors that may disrupt sports performance and recovery processes. A cascade of negative events associated with chronic stress can initiate overtraining and sleep disorders, resulting in mood changes. Poorly balanced nutrition may lead to dietary neglect, causing dysbiosis, with increased inflammatory and oxidative stress that affects many tissues and organs, directly increasing the risk of injury or infection (SMOULDER). To prevent the negative effects of chronic stress, elements described by the acronym SPARKS should be routinely implemented as preventive measures. These measures encompass both psychological-cognitive aspects (quantity and quality of sleep and post-workout recovery) and ensuring proper bodily functions, including a balanced diet rich in probiotics, antioxidants, and supplements to improve the physiological function of not only athletes. We advocate for adhering to the “SPARKS” rule for beneficial outcomes, contrasting it with the detrimental effects of embracing the “SMOULDER” formula (see Figure 1). Figure 1. Impact of SPARKS and SMOULDER on sports performance. Figure 1.Impact of SPARKS and SMOULDER on sports performance. 2. Brain Modulation 2.1. The Interplay between Selected Internal and External Factors and Sports Performance 2.1.1. Epidemiology of Stress As shown by epidemiological data, in 2018, 74% of British people felt so stressed that they had been

formula (see Figure 1). Figure 1. Impact of SPARKS and SMOULDER on sports performance. Figure 1.Impact of SPARKS and SMOULDER on sports performance. 2. Brain Modulation 2.1. The Interplay between Selected Internal and External Factors and Sports Performance 2.1.1. Epidemiology of Stress As shown by epidemiological data, in 2018, 74% of British people felt so stressed that they had been overwhelmed or unable to cope. Moreover, the same data have shown

Nutrients2024,16, 1842 3 of 27 that 51% of adults who felt stressed reported feeling depressed, and 61% reported feeling anxious [7]. Also, the most recent data covering COVID-19 indicate a signi cant percentage of the population to be suffering from chronic stress. The results of extensive reviews show that the prevalence of people experiencing stress in the general population and healthcare workers is 30 and 43%, respectively. Furthermore, the prevalence of anxiety is similarly estimated as 32 to 37%, and the prevalence of depression as 34 to 35 [8,9]. 2.1.2. Stress Prolegomena It is commonly assumed that due to a neurohormonal reaction to a stress stimulus, adrenal hormones are released into the general circulation: catecholamines, adrenaline, and noradrenaline from the adrenal medulla and glucocorticoids (GCs) from the adrenal cortex [10]. This viewpoint has been accepted since it was recognized that understanding the systemic effects of these hormones requires considering their role in the body's adaptive response to environmental stress. Selye coined the term General Adaptation Syndrome (GAS) to describe a systemic re- sponse to various internal and external stressors, encompassing both positive and negative stimuli [11]. GAS unfolds in three discernible phases: alarm, resistance, and exhaus- tion. If the originating stressors persist unchecked, they can have deleterious effects on physical and mental health. The primary mechanism of this reaction is to be realized through the so-called pituitary–adrenal axis that constitutes a multi-link chain of neuro- hormonal interaction. The adrenocorticotropic hormone (ACTH) released in the anterior pituitary gland, stimulating the adrenal cortex, leads to the seeding of cortical steroid hor- mones (mainly glucocorticoids—GCs), which triggers the appropriate peripheral adaptive response—stress. While stress is not a mental health problem in and of itself, experiencing overwhelming stress for an extended period is often called chronic or long-term stress, and it can impact both physical and mental health [8]. 2.1.3.Detrimental Effects of Chronic Activation of the Hypothalamic–Pituitary–Adrenal Axis The stressor load instigates a neuroendocrine cascade known as the hypothalamic– pituitary–adrenal (HPA) axis. This process is initiated in the hypothalamus, where corticotropin-releasing hormone (CRH) is secreted, leading to the stimulation of the ante- rior pituitary

called chronic or long-term stress, and it can impact both physical and mental health [8]. 2.1.3.Detrimental Effects of Chronic Activation of the Hypothalamic–Pituitary–Adrenal Axis The stressor load instigates a neuroendocrine cascade known as the hypothalamic– pituitary–adrenal (HPA) axis. This process is initiated in the hypothalamus, where corticotropin-releasing hormone (CRH) is secreted, leading to the stimulation of the ante- rior pituitary gland and the release of ACTH. The nal result of this axis is the activation of the adrenal cortex, prompting the synthesis and secretion of GCs. Therefore, under environmental stress or pathophysiological conditions, such as starvation, coldness, or cancer, the circulating GCs levels are signi cantly increased, decreasing the rate of protein synthesis and raising proteolysis to generate amino acids to serve as precursors for hepatic gluconeogenesis. Thus, the destructive role of GCs is well established, and the catabolic action of GCs affects the brain [12], bone [13], liver, heart [14], and skeletal muscles [15]. The indicated alterations can exert a direct in uence on athletes, resulting in an augmented susceptibility to musculoskeletal injuries [16], an increased prevalence of respiratory infec- tions [17], heightened nociceptive responsiveness [18], and lastly, substantial disturbances to sleep patterns [19]. The emotional and cognitive reactions to stress that occur during a chronically persistent stress response may take many forms, but among the most common are emotional reactions that involve negative affect. Furthermore, cognitive and emotional responses to stress are considered among the main factors contributing to sleep disor- ders [20], and as research shows, many athletes suffer from poor sleep quality, disrupting the proper stress response [21]. 2.1.4. Sleep The quality and quantity of sleep are crucial for maintaining well-being and brain and muscle functions. There is a hypothesis that during the sleep period, the brain can “turn off”, creating the proper conditions for neuronal connection regeneration [22]. It is established that sleep enhances neurometabolic, somatic, and cognitive functions. The somatic aspect

Nutrients2024,16, 1842 4 of 27 of sleep plays a vital role in enhancing neurometabolic, somatic, and cognitive functions. The somatic aspect of sleep involves tissue restoration and support for the immune and endocrine systems, while cognitively, it positively impacts learning, memory processes, and synaptic plasticity [23]. An adequate sleep amount (seven or more hours per night) highly determines sports performance [24]. Thus, nutritional strategies targeted at improving sleep and facilitating regeneration are essential for athletes. Sleep, regulated by the sleep–wake cycle and circadian rhythm, is overseen by the suprachiasmatic nucleus (SCN) in the brain. The SCN prompts melatonin secretion as darkness falls, promoting sleep [25]. Physiological changes during sleep occur in two pri- mary states: non-rapid eye movement (NREM) and rapid eye movement (REM) sleep [26]. REM is characterized by high brain activity, which seems crucial, especially for motor skills and muscle regeneration [27]. During the REM period, corticospinal pathways are partially blocked by brainstem mechanisms, accounting for the brain–body disconnection. As a result, spinal motor neuron activity is inhibited, causing total muscle relaxation and creating conditions for myo bril restoration [28]. On the contrary, during NREM, low cortical activity is observed, as manifested in slow wave activity on electroencephalography (EEG) images [29]. This phase is associated with neuronal network recruitment and recovery at various levels, including neuronal excitability regulation, energy storage replenishment, synaptic plasticity, cellular membrane regeneration, and cellular homeostasis maintenance [30]. Undisturbed sleep cycles between the REM and NREM stages continuously, ensuring all the sleep functions occur [28]. Thus, sleep is recognized as a vital recovery strategy for athletes. Post-exercise recovery is crucial for all athletes to avoid exhaustion and temporary impairments in physiological adaptation and sports results [31]. Myo bril damage in- duced by exercise triggers the adaptation process. However, chronic overtraining and inadequate recovery can lead to prolonged in ammation, impairing sports capabilities [32]. Pro-in ammatory cytokine overproduction, reactive oxygen species (ROS) generation, muscle soreness, and fatigue may additionally adversely affect sleep, contributing to mood deterioration, training motivation reduction, impairment of the autonomic nervous sys- tem, the elevation of catabolic hormones level, and thus, a decrease

adaptation process. However, chronic overtraining and inadequate recovery can lead to prolonged in ammation, impairing sports capabilities [32]. Pro-in ammatory cytokine overproduction, reactive oxygen species (ROS) generation, muscle soreness, and fatigue may additionally adversely affect sleep, contributing to mood deterioration, training motivation reduction, impairment of the autonomic nervous sys- tem, the elevation of catabolic hormones level, and thus, a decrease in anabolic processes. As a result, muscle protein synthesis deterioration and blunted sports performance are observed [33,34]. Conversely, sleep deprivation may negatively affect sports performance due to lead- ing to endocrine and immune system impairment. As a result, reduced immunity and increased vulnerability to infections were observed [35]. Moreover, negative changes may be related to a shift in hormone secretion, pro-in ammatory cytokines, and C-reactive protein (CRP) release [36]. During the sleep period, the release of hormones involved in protein synthesis occurs [37]. Anabolic hormones like testosterone, growth hormone, and insulin growth factor 1 (IGF-1) strongly in uence the skeletal muscles via activation of the phosphatidylinositol-3 kinase/protein kinase B pathway (PI3K/Akt) [37]. In addition, con- tinuous awaking triggers cortisol secretion, promoting catabolism. Leproult and coworkers have demonstrated that one day of sleep disturbances was enough to cause a cortisol level elevation [38]. Thus, the sleep period is crucial for the regeneration process, contributing to tissue repair and neuronal system refresh. Moreover, it was established that the sleep phase is a critical link between physiological adaptations to training, cognitive processes, tissue repair, and metabolic functions [39,40]. It could be distinguished into the main components: total time of sleep, quality as well as homeostasis of sleep; disruption to any of these may impair sports performance [35]. It has been noticed that sleep problems are commonly known in athletes. The quality and quantity of sleep may be disrupted by pre-competition anxiety, jet lag, lengthy travels, or training schedules [41,42]. Killer et al. observed that athletes who underwent short-term intensi ed training spent more time in bed without an increase in the effective sleep time. In addition, the number of awakenings per night and the movement time increased, indicating an elevated sleep fragmentation index

of sleep may be disrupted by pre-competition anxiety, jet lag, lengthy travels, or training schedules [41,42]. Killer et al. observed that athletes who underwent short-term intensi ed training spent more time in bed without an increase in the effective sleep time. In addition, the number of awakenings per night and the movement time increased, indicating an elevated sleep fragmentation index [43].

Nutrients2024,16, 1842 5 of 27 Some studies have shown that, after sleep loss, the procedural memory, motor skills, and regeneration may be affected. Abedelmalek et al. found that one night of partial sleep deprivation correlated with an elevated plasma interleukin-6 (IL-6) concentration after short-term maximal exercises during recovery [44]. In another study, the same researchers showed that the concentration of IL-6 and tumor necrosis factor (TNF- ) was signi cantly higher during exercise and remained higher during the 60 min recovery period in athletes who underwent sleep shortages [45]. Other clinical studies have highlighted the role of sleep in the anaerobic capacity. Souissi et al. conducted a study on judokas, showing evidence that 4 h of sleep deprivation correlates with decreased muscle strength, peak power, and mean power during an afternoon Wingate test session compared with a night of standard sleep [46]. Both total and partial sleep deprivation may also be related to decreased aerobic capacity and muscle strength. In the study by Cullen et al., the aerobic capacity, maximal handgrip strength, and countermovement jump were reduced after total sleep deprivation by 11, 6, and 11%, respectively. At the same time, the aerobic capacity and countermovement jump were impaired by 4 and 5% following partial sleep disturbance among recreationally active males [41]. An inadequate amount and quality of sleep may also cause a decline in mental func- tions and well-being [47]. Therefore, increasing the sleep duration is associated with bene ts in terms of alertness, psychomotor functions, executive function performance, and motivation level [47]. To sum up, the data mentioned above strongly support the impor- tance of the sleep amount (seven or more hours) and quality as a critical factor promoting optimal regeneration processes, bene ting both the central nervous system and skeletal muscle tissue health. 3. Nutritional Strategies 3.1. Supplementation Supporting Performance/Recovery from Exercise-Induced Muscle Damage 3.1.1. Melatonin Melatonin (N-acetyl-5-methoxytryptamine) is primarily produced by the pineal gland, with smaller amounts synthesized by other organs like the gastrointestinal tract, liver, and adrenal cortex [48]. Its rhythmic secretion is regulated by the circadian cycle, in u- encing sleep timing, nocturnal blood

This review evaluates nutritional strategies and their impact on brain health and sports performance.