Reliability and Validity of a Novel Reactive Agility Test with Soccer Goalkeeper-Specific Movements.

The purpose of this study was to develop a reactive agility test with soccer goalkeeper (GK)-specific movements (G-RAT) and to examine the reliability and validity of college-aged GKs. We designed a five-branch star-shaped course with diving and ball-catching movements under reactive conditions. In the setup, a start−goal line was set on the top of a branch and 3.5 m away from the center of the star-shaped setting. Content validity was assessed by six experts, and the item-content validity index (I-CVI) was calculated. Thirty-three male GKs performed the test trial twice. One test trial of G-RAT consists of three shuttles from the start−goal line to diving and ball-catching. For the reactive condition, GKs were instructed on which ball directions should dive when their body trunk reached 1.5 m away from the start−goal line. GKs were classified into regular (R) or non-regular (NR) groups. The intraclass correlation coefficient (ICC) and the receiver operating characteristic (ROC) curve analyses were used to assess the reliability and predictive power as convergent validity. The I-CVI was 0.83, which was greater than the acceptable level of 0.78. The ICC value was 0.94 (p < 0.01; 95% confidence interval (95%CI), 0.88−0.97). The GKs completed the test 14.3 ± 0.7 and 15.3 ± 1.0 s in the R and NR group (p < 0.01; Cohen's d = 0.89), respectively. The area under the curves of G-RAT was 0.80 (95%CI, 0.64−0.96). These results show that a GK-specific agility test under reactive conditions would have sufficient reliability and both content and convergent validity in college-aged GKs.

Content validity and reliability of an enjoyable multicomponent agility test for boys: The N-challenge test.

Agility is a crucial fitness component for success in sports and daily playful activities for children. The purpose of this study was to develop a multicomponent agility test, N-challenge, to determine the content validity and reliability of N-challenge, and to investigate the enjoyment level of N-challenge among elementary school boys. N-challenge consisted of six sections and total running time. The running time of N-challenge was measured in a single trial concomitantly with timing/speed gates. Content validity was assessed by eight experts in sports science. To measure reliability, intraclass correlation coefficient (ICC) and standard error of measurement (SEM) were calculated using a test-retest procedure. The enjoyment levels of the boys who performed N-challenge were assessed using a questionnaire. The item-content validity index of the total running time of N-challenge was 1.00. The ICC of the total running time of N-challenge was 0.97 (95% confidence interval: 0.96-0.98), which was categorized as an almost perfect level of reliability. The SEM of N-challenge was 0.18 s (1.9%), indicating good absolute reliability. Approximately 95% of the boys showed enjoyment after performing the test. These results suggest that N-challenge has adequate content validity and excellent reliability as an agility test for boys.

Non-linear growth trends of toe flexor muscle strength among children, adolescents, and young adults: a cross-sectional study.

PURPOSE: There are only a few studies on the muscular strength of the foot in children and adolescents; thus, the developmental pattern and normative data of these populations during growth are unclear. We sought to elucidate the developmental pattern of the foot muscle strength among children, adolescents, and young adults compared with that of the hand. METHODS: A total of 747 children, adolescents, and young adults participated in this study, and their maximum isometric toe flexor strength (TFS), hand grip strength (HGS), and foot length were measured. RESULTS: TFS was correlated with HGS (r = 0.785), age (r = 0.659), height (r = 0.757), body mass (r = 0.737), and foot length (r = 0.594). Multiple regression analyses revealed that TFS was correlated with age (ß = 0.243 in boys; ß = 0.461 in girls), squared value of age (age2; ß = - 0.296 in boys; ß = - 0.260 in girls), and body mass (ß = 0.256 in boys; ß = 0.311 in girls) in both sexes, indicating a non-linear relationship between age and TFS development. In a regression model for HGS, age was a significant variable, but not age2. HGS increased linearly from childhood until young adulthood, whereas TFS increased from childhood until adolescence and then levelled off. CONCLUSION: Our results demonstrate that TFS has a different developmental pattern compared with HGS.

Inverse Relationship between Sleep Duration and Cardio-Ankle Vascular Index in Children.

AIM: Poor sleep has been shown to be associated with the development of cardiovascular risk factors, such as obesity, in both adults and children. This study aimed to investigate the relationship between sleep duration and arterial stiffness indices in Japanese children and early adolescents. METHODS: The data on 102 students (56 males, 46 females; mean age, 11.9±1.8 years) were analyzed. As non-invasive arterial stiffness parameters, the cardio-ankle vascular index (CAVI) and heart-ankle pulse wave velocity (haPWV) were evaluated. Their students' sleep habits (bedtime and wake times on a usual weekday) were investigated using questionnaires, and based on these, their sleep durations were calculated. RESULTS: The CAVI values in the males and females were 4.8±0.9 and 4.7±0.9 (arbitrary unit), respectively. haPWV values in the males and females were 5.5±0.6 and 5.4±0.6 m/s, respectively. Sleep duration in the males, but not in the females, was negatively correlated with CAVI (r=－0.356) and haPWV (r=－0.356), suggesting that students with short sleep duration could have increased arterial stiffness. After adjusting for confounders, such as age, sex, systolic blood pressure, heart rate, adiposity, and physical fitness, the correlation of sleep duration with CAVI, but not with haPWV, was still significant (partial r=－0.253, p＜0.05). CONCLUSION: Our findings suggest that shorter sleep duration influences arterial stiffening even in childhood.

Toe flexor strength and foot arch height in children.

PURPOSE: The aim of this study was to investigate the muscle strength and arch height of the foot in the standing position and the relations between these indices and physical performances involving the lower limbs in children. METHODS: A total of 301 elementary school children (third grade: n = 158, age = 8.6 ± 0.5 yr; fifth grade: n = 143, age = 10.6 ± 0.5 yr; means ± SD) participated. The maximal isometric toe flexor strength (TFS) in the standing position was measured using a toe flexor dynamometer. Foot arch height was assessed as the distance between the navicular tuberosity of the foot and the floor in the standing position, and foot arch height relative to the foot length was represented by the foot arch index (FAI). For physical performance involving the lower limbs, 50-m sprint, standing broad jump, repeated side step, and rebound jump were measured. RESULTS: There were no significant correlations between TFS and FAI and between relative TFS (relative TFS = TFS/body mass) and FAI. Relative TFS was significantly correlated with all physical performance tests. No significant correlations among FAI and physical performances were found, except for rebound jump ability in fifth graders. After multiple regression analyses adjusting for gender and body mass, TFS was the only significant correlating factor for all physical performances involving the lower limbs. CONCLUSIONS: This study showed that TFS was associated with enhancement of some measures of lower limb physical performance in children. These results suggest that foot function should be evaluated with both the muscle strength and arch height of the foot in children.