The global pandemic of childhood physical inactivity and the associated reduction in physical fitness have become the major health problem. Based on such background, there is growing interest in child development research to investigate the associations among physical fitness, cognitive function, and the underlying neurobiological mechanisms. In the present narrative review, we first summarize the findings from behavioral studies that examined the relations of childhood fitness to academic performance and executive function. Because these behavioral findings remain controversial due to methodological inconsistencies, we further discuss differences in independent variables (e.g., physical activity vs. fitness), confounders (e.g., socioeconomic status), study designs (e.g., cross-sectional vs. randomized controlled trial), and assessments used to measure academic performance and executive function (e.g., task difficulty). Subsequently, we introduce neuroimaging studies on brain volume, task-evoked brain activation, and white matter fiber integrity which may provide mechanistic insights into the behavioral observations. To date, several randomized controlled trials using advanced imaging techniques showed that regular physical activity may change brain activations during executive function tasks and improve white matter fiber integrity in children. Collectively, our literature review suggests that regular physical activity leading to increase in physical fitness is likely to contribute to healthy brain development. Nevertheless, the current evidence is still limited and inconclusive, thus further rigorously designed randomized controlled trails are needed to clarify the association between childhood fitness and brain development.

Green tea catechins are well known to be one of polyphenols, and its regular ingestion induces body fat reduction in obese individuals. Cocoa polyphenols of high-cocoa chocolate can also improve arterial stiffness. However, it is unclear whether green tea catechins improve body fat and arterial stiffness even in healthy young adults. Therefore, this study aimed to examine the effects of regular green tea intake on body fat and arterial stiffness in young adults. This randomized, controlled, parallel-group intervention study included 53 Japanese college students (mean age, 21.1 ± 0.1; men, n = 40; women, n = 13). They were randomly divided into three groups: control group (n = 14), intervention I group (n = 19), and intervention II group (n = 20). The participants ingested 500 ml/day of commercially available natural water (0 mg of catechin/day) or green tea (intervention I group, 200 mg of catechin/day; intervention II group, 400 mg of catechin/day) for 4 weeks. After 4 weeks of intervention period, no significant changes in body weight, body mass index, pulse wave velocity, and cardio-ankle vascular index were observed in all groups. However, body fat and carbon dioxide output significantly reduced only in the intervention II group. With the level of catechin concentrations increasing, significant decreasing trends were found in body fat changes and respiratory exchange ratio changes. Therefore, these findings suggest that four weeks of regular green tea intake would reduce body fat, but not arterial stiffness, in young adults.

Dynamic knee valgus is considered a risk factor for anterior cruciate ligament (ACL) injuries. This study identified how knee in distance (KID) and hip out distance (HOD) affect one’s lateral trunk lean (LTL). The results were also tested for reliability. Fifteen female basketball players (30 legs) from a university participated in this study. The participants performed single-leg squats by bending the knee of the supporting leg to 60°. The trials were recorded using a video camera. The KID, HOD, and LTL were measured with two-dimensional images using the Dartfish software, which measured the maximal knee valgus. The Pearson’s correlation coefficient was used to measure the correlation between dynamic knee valgus (KID and HOD) and LTL. Additionally, the Interclass Correlation Coefficient (ICC) was used to measure the reliability of the KID, HOD, and LTL data sets. The statistical significance was established at a level of p<0.05. Results showed that the KID and LTL had a significantly negative correlation, measured at r=-0.227, p<0.05. The ICC (2.1) values were: 0.83 for HOD, 0.99 for KID, and 0.96 for LTL; while the ICC (1.2) values were: 0.86 for HOD, 0.83 for KID, and 0.85 for LTL. The two-dimensional analysis technique revealed that the values were highly reliable. In sum, dynamic knee valgus had a negative correlation with LTL during single-leg squats. Therefore, it was suggested that the factors of dynamic knee valgus might be evaluated using LTL on two-dimensional screening test.

This study aimed to explore the association of breakfast (BF) dietary patterns with physical activity (PA) and fitness in elementary school children. This study enrolled 242 school children of 5th and 6th grade. BF dietary patterns were evaluated by questionnaires on whether the child consumes the following food categories: staple, main dish, side dish, soup, milk or dairy products, and fruit. Individual PA levels were categorized into high and low PA groups using a PA scale for children. The measured 8 assessments of physical fitness scores were converted to Z-scores normalized for sex, age and height as previously reported. High PA group had significantly higher scores in running and muscle strength as well as in the total score of physical fitness. The frequency of eating BF (with or without BF omission) and the level of PA were not significantly related in both sexes. However, in girl children, BF, including staple, main dish, side dish, and soup, was significantly more prevalent in high PA group than low PA group (55.9% vs. 32.1%; χ² = 5.638, p = 0.018). A similar tendency was observed in girls who had BF, including staple, main dish, and side dish (49.0% vs. 31.1%; χ² = 3.720, p = 0.054). No associations between dietary patterns and PA were observed in boys. The results suggested that the frequency of eating BF was not associated with PA levels, which was significantly related to physical fitness in Japanese 5th and 6th grade elementary school children. In contrast, the results indicated that a high-quality BF dietary pattern, such as a meal including staple, main dish, side dish, and soup, might be associated with a physically active girl child.

The Star Excursion Balance Test (SEBT) is a dynamic balance test used for the screening of injuries in the fields of sports; however, we do not clearly understand what factors of the SEBT are associated with the occurrence of injury. We hypothesized that the trunk movement would be a key factor related with the maximum reach distance (MRD) of the SEBT. The purpose of this study was to examine the relationship of the MRD during the SEBT with trunk lean angles and ankle flexibility. We recruited 19 healthy male athletes (age: 21±0.8 years, height: 170.2 ± 6.6 cm, weight: 65.2 ± 6.9 kg) and measured the MRD of the SEBT including anterior, posteromedial and posterolateral directions, the trunk lean angles at MRD, and the maximum ankle dorsi-flexion angle (DFA). The trunk lean angles were measured with the Direct Linear Transformation (DLT) method. The DFA was measured by the weight-bearing-lunge-test. We used Pearson’s correlation coefficient. There were positive correlations between the anterior-MRD and DFA; the posteromedial-MRD and the lateral trunk angle; the posterolateral-MRD and the forward trunk angle (r =.58, r =.47, r =.62, p<0.05, respectively). For future study, we need to consider the trunk movement and to focus on other factors such as muscle strength, muscle activities, center of mass, and center of pressure, which contribute to the MRD of the SEBT.