Diet and Sport Psychology

Athletes are prone to suffer from sleep disruption and poor quality of sleep due to their occupational circumstances, including muscle fatigue, constant and/or long term travel, scheduled exercise and competition times (during the early hours of the morning or evening). Nutrition is paramount for performance, workout and post-workout recovery. Ensuring a diverse diet and adequate nutritional supplementation may give athletes the best chances to improve both quality and quantity of sleep. In this narrative review, Gratwicke et al. (2021) discuss studies relevant to athletes that investigate nutrition, supplements, and beverages that may improve sleep quality and quantity. Six databases were searched for relevant literature from November 2020 up to study initiation. Due to the lack of literature investigating the subpopulation of athletes, inclusion criteria for relevant studies were increased to allow review of studies that investigated healthy adults, regardless of athletic status. The results demonstrated that foods with a high glycemic index somewhat improved sleep, and that tart cherry juice enhanced sleep quantity, while herbal supplements improved sleep quality. Interestingly, kiwifruit and protein supplements improved both sleep quality and quantity. The authors comment that nutritional interventions may present an efficient method to target sleep quality and quantity, however, more research is required to understand dosing, nutritional sources and timing of interventions with respect to training, travel, and competitions. [NPID: sleep, athletes, recovery, team-sport, macronutrients, supplements]

In this study, Natàlia et al. (2022) examined how high (HGI) or low glycemic index (LGI) high-carbohydrate meals affected athletes' sleep quality. For the duration of two days during a basketball championship, nine male basketball players were given high-carbohydrate meals (dinner and evening snack) with HGI or LGI. Data on sleep was collected in both quantitative and qualitative measures, including sleep latency (LAT), sleep efficiency (EFIC), Wake After Sleep Onset (WASO), and sleep time, using actigraphy and sleep diary. Dietary intake, satiety, sleepiness, glycemic response, salivary cortisol and melatonin were among relevant parameters investigated for the study. The results revealed that the athletes scored higher on LAT and WASO and lower on nocturnal sleep time when compared to recommended scores. Although the athletes did not show any changes in sleep or hormonal levels in response to GI alterations, a relationship was seen between sleep and diet. Specifically, the amount of energy consumed per day was found to adversely affect sleep efficiency and nocturnal total sleep time and WASO favorably, regardless of meals consumed at night. However, no changes were seen in salivary cortisol and melatonin in response to GI. The authors comment that food eaten throughout the day affects sleep parameters of basketball athletes more significantly than altering the GI of meals eaten on the pre-game night, however, conducting more studies is paramount to further outline this complex interaction. [NPID: Sleep, glycemic index, athletes, dietetics]

This 2013 study analyzed the eating behaviors of 138 male football referees and aimed to find out if these behaviors correlate with self-efficacy. The trial participants all refereed at regional level in Polish football. The men were asked to fill out some questionnaires on diet and were then tested on self-efficacy. Most of the referees consumed at least 3 meals a day and preferred to hydrate by drinking unsweetened beverages. A little over 71% of them included cereal products in every meal, 70% avoided fast food, and 66% hydrated properly after training. Over half of the respondents also avoided sweetened fizzy drinks, ate fish at least once a week, and restricted their sweets and snack intake. There was a link identified between high self-efficacy with unsweetened drinks consumption and correctly replenishing fluids during and after training. Furthermore, referees with a high sense of self-efficacy were more likely to consume fruits and vegetables, fish, dairy products, and cereals at the recommended frequency, and avoid energy drinks, when compared with referees with low self-efficacy. In conclusion, male football referees with higher self-efficacy showed more favorable nutritional choices than referees with lower self-efficacy. [NPID: sports psychology, sports, referees, athletes, football, behaviors, diet, fast food, hydration, sweets, snacks, self-efficacy, performance, energy drinks]

In this 2016 study, cyclists undergoing intermittent fasting for Ramadan were assessed on their cognitive function. The participants fasted during the daylight hours. Various cognitive tests were conducted before and after Ramadan, and in the 1st and 4th weeks of this holy month of fasting. An increase in perceived fatigue and delayed onset muscle soreness was noticed in the 4th week of Ramadan. Moreover, the eleven cyclists showed disturbed sleeping patterns during Ramadan. Duration of light sleep and number of awakenings significantly increased during this period. Following the holy month, the study observed decreased durations of deep and REM sleep stages in the athletes. With regards to the cognitive tests, reaction and movement times did not vary over the study period. There were, however, higher incidences of false alarms in the Rapid Visual Information Processing (RVP) tests, suggesting reduced impulsivity. Compared to baseline, overall accuracy was higher during Ramadan (1st and 4th weeks) and post-Ramadan. In the fourth week of fasting, accuracy was higher at 0-2 am compared to 4-6pm. In conclusion, the intermittent fasting that takes place during Ramadan did not negatively affect the cognitive performance of trained cyclists from the Middle East. [NPID: fasting, intermittent fasting, Ramadan, Middle East, Muslim, cyclists, athletes, cognition, sleep]

The aim of this 2021 research study was to examine the effects of a nutritional supplement on inflammatory and stress biomarkers among professional athletes and inactive people. This test supplement was called Gasteel Plus and contained both probiotics and prebiotics. The trial also evaluated its impact on parameters related to physical and mental health, such as metabolic profile and physical activity. The study participants included professional football players in the Second Division B of the Spanish League, and sedentary students. These subjects were randomly chosen to receive either a placebo (the control group) or the synbiotic (experimental group). The synbiotic supplement (Gasteel Plus) was found to improve physical activity, sleep quality, and perceived general health, stress, and anxiety levels but only among the athletes. Furthermore the synbiotic appeared to affect certain inflammatory/immune and stress biomarkers such as dopamine, interleukin-1β, and corticotropin-releasing hormone (CRH) but the exact effects depended on the baseline readings. To summarize, synbiotic nutritional supplements can enhance anxiety, stress, and sleep quality, especially in sportspeople. [NPID: anxiety, stress, sleep quality, synbiotic, probiotic, prebiotic, supplements, diet, nutrition, inflammation, athletes, sports psychology]

This 2020 study examined 182 weight class athletes from colleges in Gyeong-gi Province, South Korea. Depending on the participants’ level of weight control, the athletes were categorized into high and normal weight loss groups. Most people were in the high weight loss group, meaning they must cut their weight by more than 5% of body weight to compete. There were differences between the high and normal weight loss groups in various aspects of cutting weight, including method, satisfaction, as well as frequency, magnitude, and duration of weight loss. The study found that athletes’ weight control levels were related to their eating habits during the training period and during the weight control phase. Compared to the normal weight loss group of athletes, the high weight loss athletes agreed more strongly on the flaws of rapidly cutting weight and showed less faith in making weight for their weight class and less confidence in controlling their overeating post-match. These high weight loss competitors exhibited more inappropriate eating behaviors than normal weight loss athletes, particularly during the weight control period. Those athletes who have to lose relatively higher percentage weight had lower self-efficacy and poorer eating behaviors during the pre-competition period, compared to athletes who lose a “normal” weight percentage. [NPID: sports, weight loss, athletes, South Korea, eating habits, weight control, diet, nutrition]

This 2020 study recruited both men and women wrestlers in Turkey to analyze the relationship between emotional eating and mindfulness among active wrestlers. Data was collected from 382 volunteering wrestlers by handing out personal information forms and applying the Emotional Eating Scale as well as the Mindfulness Inventory for Sport. On average, the national wrestlers ate more food types than non-national athletes and were rated higher in guilt and emotional eating. Higher scores in the Mindfulness Inventory were related to less ability to refocus. Greater disinhibition was also connected to reduced awareness. The study found that guilt, non-judgment, refocusing, and the Mindfulness Inventory scores were positively linked, although the relationship was weak. A weak negative correlation was identified between the participants’ emotional eating scales, awareness, ability to refocus, and non-judgment. The author Şahin concludes that the physically and psychologically negative effects of emotional eating may contribute to reduced levels of awareness in athletes. [NPID: sports psychology, wrestlers, Turkey, athletes, emotional eating, mindfulness]

The purpose of this 2020 study was to find out if the social skills of a trainer can influence aspects of the athletes’ psychological health and diet. Trigueros et al. kept an eye on the athletes’ coping capacity, psychological well-being, and eating habits since these factors are important for athletes to achieve success during competition. The study managed to sign up 1547 athletes and 127 trainers. Positive correlations were found between trainers’ prosocial behaviors and athletes’ resilience. Conversely, increased antisocial behaviors were linked with poorer resilience. Those with greater resilience showed lower probability of having anxiety, stress, and depression, but having lower resilience tended to mean higher risk. In addition, these psychological disorders were less prevalent in healthy eaters than in those with unhealthy diets. Overall, these findings highlight the importance of positive social environments in promoting mental health and healthy eating habits in athletes. [NPID: nutrition, sports psychology, resilience, social behaviors, trainers, athletes, anxiety, depression, stress, mental health]

This 2020 study tries to better understand the choking phenomenon, which is described as the serious decline in skilled technical movements experienced because of high perceived pressure. In the first experiment, 20 diving athletes were tested in low- and high-pressure situations. One of the objectives was to gather data on the relationship between the gut microbiota and the choking phenomenon among diving athletes. The gut microbiota composition of those who “choked” were compared to that of athletes who did not “choke” and performed under pressure. The second aim of this study was to determine if the choking phenomenon is affected by regulation of the gut microbiota via drinking yogurt. Ten divers consumed higher amounts of yogurt per day while the remaining 6 divers ate lower amounts of yogurt every day. The results indicated that “chokers” tended to have significantly more Veillonellaceae in their guts, compared to “non-chokers”. Choking was also negatively associated with the population sizes of Bifidobacteriaceae and Lactobacillaceae in the gut. Also, the abundance of Bifidobacteriaceae was significantly higher in the high yogurt group than in the low yogurt group. It was also found that the high yogurt group was less likely to “choke” than the low yogurt group. The study uncovered that the gut microbiota may influence the choking phenomenon in elite diving athletes. The consumption of the yogurt containing B. animalis subsp. Lactis can improve the athletes’ ability to perform under pressure. [NPID: yogurt, supplement, choking, swimmers, divers, diving, sports psychology, gut microbiota]

This 2018 study investigates whether following a vegetarian or vegan diet can modulate quality of life in athletes. There is evidence indicating that these diet types can positively affect exercise performance in athletes, but there is limited data on its influence on well-being and psyche. This study examined the quality of life scores of endurance runners, and compared those who adhere to an omnivore diet with those who eat a vegetarian or vegan diet. The 281 runners (male and female) completed questionnaires that assessed physical health, psychological well-being, social relationships, and environmental conditions. More of the participants followed a vegetarian or vegan diet rather than an omnivore diet (158 vs. 123). The final analyses were performed on the 173 runners who met the inclusion criteria. Among this sample, there were 103 half-marathoners and 70 marathoners/ultramarathoners. The study also added a control group of 10km runners. The overall quality of life scores among the sample was high. Men were found to score higher than women overall due to the high scores in the physical health and psychological well-being dimensions. Eating an omnivore diet appeared to influence environmental scores among women, and affected social relationship scores among men. In summary, endurance runners showed high quality of life scores, regardless of the distance they run or diet choice. The vegetarian and vegan diet may be equal alternatives to the omnivore diet. [NPID: runners, athletes, vegetarian diet, vegan diet, healthy diets, quality of life, sports psychology, running, marathon running]

This 2016 study determined the prevalence rate of disordered eating among a sample of female college athletes by conducting several tests and surveys. Although experts have yet to confirm the factors that contribute to disordered eating in female college athletes, emotional regulation has been identified as a potential correlate. An aim of this study was to assess emotional regulation, body dissatisfaction, sport type, a family history of eating disorder, and BMI as potential predictors of disordered eating. One hundred and fifty-one female participants completed the Minnesota Eating Behavior Survey and the Eating Attitudes Test-26 to identify disordered eating. The results demonstrated different incidence rates depending on the assessments, but roughly 6.6 to 10.6% of the young athletes exhibited disordered eating. The prevalence rates of disordered eating did not vary by sport type (no difference between performers in weight-sensitive and less weight-sensitive sports). Another finding was that increased emotional regulation issues and body dissatisfaction were significant predictors of disordered eating. This revelation warrants further investigation of emotional control and dissatisfaction with respect to disordered eating in female college athletes. [NPID: college, athletes, sports psychology, emotional regulation, disordered eating, body dissatisfaction, sports nutrition]

This 2019 article explores several plant-derived phytochemicals that can modulate physiological aspects in individuals and discusses its potential implications in sports psychology. Different phytochemicals may have unique toxicity levels and effects on the brain, and this tends to be dictated by the structural groups of the phytochemicals (phenolic, terpenes, alkaloids). The phenolics like polyphenols are natural components of the human diets but when consumed in high quantities they can improve cardiovascular function and have been associated with long-term brain health. Short-term supplementation with polyphenols has been shown to influence cognitive function and alertness/arousal. Terpenes typically do not make their way into the human diet, but monoterpenes derived from edible herbs such as sage and peppermint for example can enhance aspects of cognitive function and alertness. Similar effects are seen with diterpene-rich Ginkgo biloba extracts and triterpene-containing extracts from plants such as ginseng and Bacopa monnieri. With regards to alkaloids, these phytochemicals are generally inappropriate in a sporting context due to toxicity and legal status. However, there is evidence to suggest that single doses of caffeine and nicotine may enhance relevant aspects of cognitive function and/or alertness. The author Kennedy believes that it may be challenging to focus on these benefits due to the long-term negative impacts of these alkaloids, such as habituation and withdrawal. It may be worthwhile for future research to investigate the efficacy of volatile terpenes, triterpene-rich extracts, and products combining low doses of caffeine with other phytochemicals. [NPID: phytochemicals, sports psychology, brain, alertness, cognitive function, alertness, caffeine, nicotine, ginkgo biloba, Bacopa monnieri]

In this 2013 study, a group of junior football players were asked how often they eat certain food items and were examined on their self-efficacy. The plan was to determine if there is a correlation between the young athletes’ self-efficacy and the frequency at which they consume specific food items. Just over 55% of the study participants reported moderate self-efficacy, while just below 45% were found to have high self-efficacy. Higher self-efficacy was related to more regular intake of whole wheat bread, brown rice, high-fat cottage cheese, and butter. Those who ate poultry meat, and olive and plant oils less frequently were more likely to have higher self-efficacy. When directly comparing athletes with high self-efficacy to athletes with moderate self-efficacy, those with higher self-efficacy selected whole wheat bread, brown and white rice, fruits, low-fat milk, high-fat cottage cheese, butter, and sweetened fizzy drinks more frequently. This subgroup of athletes with high self-efficacy also consumed poultry meat, pastries, and sweets less often than those with moderate self-efficacy. Based on these results, this study concludes that high self-efficacy promotes more balanced nutritional choices. [NPID: nutrition, athletes, sports psychology, football players, self-efficacy, nutritional choices, diet]

In this 2021 study, 13 university badminton players were randomly chosen to either receive a probiotic or a placebo drink for six weeks. The subjects’ fitness levels were monitored through various tests and exercises such as the 20-meter shuttle runs, handgrips, vertical jumps, 40-meter dash, and the T-test. In addition, the researchers wanted to determine the effect of taking probiotics on the badminton players’ competitive anxiety, perceived stress, and mood. These psychological outcomes were assessed by administering questionnaires. Anxiety and stress levels decreased considerably (by 16% and 21% respectively) in the probiotic group after 6 weeks. In contrast, there was no difference found in the placebo group. The athletes taking probiotics also demonstrated enhanced aerobic capacity during the intervention. But the probiotic supplementation did not seem to affect speed, strength, leg power, or agility. Benefits of taking probiotics included better aerobic capacity and less anxiety and stress. [NPID: athletic performance, anxiety, stress, mood, badminton players, university, probiotics]

The aim of this 2020 study was to determine the effect of taking probiotic supplements every day on anxiety-induced physiological characteristics among competitive football players. It is said that footballers who undergo intensive training and frequently compete in competitions are vulnerable to psychological disorders, while probiotics are believed to reduce the risk of developing these disorders. In this trial, the football players were either given probiotics or a placebo drink over 8 weeks, before being tested on outcomes such as cognition. In addition, the athletes had their heart rates measured, their brain activity assessed (electroencephalography), and were examined on their electrodermal responses. There was no notable difference between the probiotics and placebo groups after 8 weeks of intervention, according to the electroencephalography, electrodermal assessments, and heart rate monitors. However, the cognitive test reaction times significantly improved in the probiotic group, compared with the placebo group. These results suggest that probiotics supplementation may be capable of modulating brain waves in a way that enhances training, brain function, and psychological factors in competitive football players. [NPID: probiotics, brain function, athletes, athletic performance, sports, sports psychology, heart rate, brain waves, football players]

According to this 2019 article, probiotic supplements are being used by athletes to promote health and athletic performance. Noorifard et al. explains that intensive exercise on the professional level can increase production of free radicals and stress hormones, cause damage to body tissues, and reduce immune activity. This study investigated if probiotic supplementation could affect psychological health and the amount of oxidative stress enzymes in athletes. The 40 participants (swimmers) were split into two groups of 20. One group received one glass of probiotic juice every day for 12 weeks (this was the test group), while the other group received placebo juice for 12 weeks (the control group). After 12 weeks of this intervention, the level of antioxidants was significantly higher in the test group compared with the control group. In addition, the group receiving the probiotics showed better psychological parameters than the group taking the placebo drinks. In conclusion, the consumption of the probiotic juice positively influenced the athletes’ antioxidant system and mental health. [NPID: antioxidants, mental health, swimmers, athletes, probiotics, exercise, supplements, immunity]

This 2016 study analyzed the amount and types of dietary supplements taken by American football players and measured their self-efficacies (their beliefs in their individual capacity to execute behaviors necessary on the football field). The objective was to assess the relationship between dietary supplement intake and self-efficacy in American football players. The 100 recruited athletes were aged between 20-30 years and Polish. A survey distributed online revealed that the most popular ergogenic supplements among these American football players were isotonic drinks, vitamin and mineral supplements, and protein concentrates. Around 74% of the athletes consumed isotonic drinks, whereas supplements like caffeine and/or guarana were consumed by 44% of the sample population. Other supplements such as BCAA amino acids (39%), creatine (36%), carbohydrate concentrates (30%) and omega-3 fatty acids (30%) had lower user percentage rates. The popularity of some dietary supplements varied depending on the general self-efficacy level of the athletes. The study concluded that sportsmen with lower levels of self-efficacy used multivitamin supplements significantly more often, compared with athletes reporting higher levels of self-efficacy. [NPID: athletes, athletic performance, self-efficacy, dietary supplements, supplementation, vitamins, isotonic drinks, amino acids, creatine, sports]

The aim of this 2018 study was to investigate whether adherence to the Mediterranean diet is connected to motivation in sport. Since habits can vary from nation to nation, this relationship was examined using university students from the 2 countries Romania and Spain. These students had an average age of around 21 and specialized in physical education. Using questionnaires and analysis indices, it was found that students from Spain had a high adherence to the Mediterranean diet and scored highly in task-oriented motivation. This task-oriented motivation trait was associated with low adherence to the Mediterranean diet in the Spanish students. Whereas participants from Romania showed higher scores in ego-oriented motivation, which showed correlations with medium adherence to the Mediterranean diet. This study reveals that Spanish university students may closely follow the Mediterranean diet. Moreover, these findings demonstrate that the motivation of performing better than other athletes may be related to greater adherence to the Mediterranean diet. [NPID: Mediterranean diet, healthy diets, athletes, physical exercise, athletic performance, motivation, motivational climate, university students]