There is a persistent need in sport science for developing a measuring tool that is affordable, portable, and easy to use. We aimed to examine the concurrent validity and test–retest reliability of the My Jump 2 app compared to a validated OptoJump instrument for measuring jump performance during the squat jump (SJ), countermovement jump (CMJ), and CMJ free arms (CMJAM) in primary school children. A total of 48 participants (11–14 years age), volunteered to participate in this research. The jumps were recorded with a validated OptoJump photoelectric cell system and a concurrent device (iPhone X through My Jump 2 app) at the same time. The participants repeated the testing procedure after two weeks to assess the reliability of the measurements (ICC). Systematic bias between sessions and tools was evaluated using the paired samples t-test and Bland and Altman analysis. High test–retest reliability (ICC > 0.89) was observed for all measures’ in-between conditions. Very large correlations in the total sample were observed between the My Jump 2 app and OptoJump for SJ (r = 0.97, p = 0.001), CMJ (r = 0.97, p = 0.001), and CMJAM (r = 0.99, p = 0.001). Bland and Altman’s plot depicting limits of agreement for the total sample between the OptoJump and My Jump 2 show that the majority of data points are within the 95% CIs. The results of this study suggest that My Jump 2 is a valid, reliable, and useful tool for measuring jump performance in primary school children.

Regular exercise during school hours is encouraged since childhood obesity has reached epidemic proportions. Moreover, a great majority of adolescents do not meet the recommendations for moderate-to-vigorous physical activity. The present study aimed to determine the effects of school-based high-intensity interval training (HIIT) and nutrition intervention on body composition and physical fitness in overweight adolescent girls. Forty-eight girls were included in the study, of whom 24 (age = 15.5 ± 0.7 years) were randomized to a experimental group (EXP) (HIIT and nutrition intervention school-based program) and 24 (age = 15.7 ± 0.6 years) to a control group (CON) that maintained their usual physical education activities. HIIT consisted of 10 stations of own bodyweight exercise and was done three times per week for eight weeks. Moreover, the EXP participated in the nutrition program led by a nutritionist two times a week. Apart from body composition assessment, participants performed countermovement jump (CMJ), medicine ball throw, hand-grip test, and Yo-Yo Intermittent Recovery Level 1 Test (YYIRT1). A significant effect of group (EXP vs. CON) x time (pre vs. post) interaction was observed for weight [F(1,44) = 7.733; p = 0.008], body mass index [F(1,44) = 5.764; p = 0.020], body fat (in kg) [F(1,44) = 17.850; p < 0.001], and body fat (in %) [F(1,44) = 18.821; p < 0.001]. Moreover, a significant interaction was observed for the medicine ball throw [F(1,44) = 27.016; p < 0.001] and YYIRT1 [F(1,44) = 5.439; p = 0.024]. A significant main effect for time was found for hand grip [F(1,44) = 9.300; p = 0.004] and CMJ [F(1,44) = 12.866; p = 0.001].The present study has demonstrated that just eight weeks school-based HIIT and nutrition intervention, including three sessions a week, can improve body composition and muscular and physical aerobic performance in overweighted adolescent girls.

This study aimed to examine the reliability, validity, and usefulness of the smartphone-based application, My Jump 2, against Optojump in recreationally active adults. Participants (18 women, 28.9 ± 5.6 years, and 26 men, 30.1 ± 10.6 years) completed squat jumps (SJ), counter-movement jumps (CMJ), and CMJ with arm swing (CMJAS) on Optojump and were simultaneously recorded using My Jump 2. To evaluate concurrent validity, jump height, calculated from flight time attained from each device, was compared for each jump type. Test-retest reliability was determined by replicating data analysis of My Jump 2 recordings on two occasions separated by two weeks. High test-retest reliability (Intraclass correlation coefficient (ICC) > 0.93) was observed for all measures in both male and female athletes. Very large correlations were observed between the My Jump 2 app and Optojump for SJ (r = 0.95, p = 0.001), CMJ (r = 0.98, p = 0.001), and CMJAS (r = 0.98, p = 0.001) in male athletes. Similar results were obtained for female recreational athletes for all jumps (r > 0.94, p = 0.001). The study results suggest that My Jump 2 is a valid, reliable, and useful tool for measuring vertical jump in recreationally active adults. Therefore, due to its simplicity and practicality, it can be used by practitioners, coaches, and recreationally-active adults to measure vertical jump performance with a simple test as SJ, CMJ, and CMJAS.

This study investigated the effects of the Teaching Games for Understanding (TGfU) model implemented in physical education classes on volleyball skills and enjoyment in secondary school students. A total of 54 students (18 girls) from two classes participated in this study, of whom 28 (age = 15.5 ± 0.7 years) were randomized to a TGfU model (EXP) group and 26 (age = 15.7 ± 0.6 years) to a control group (CON) that maintained their usual physical-education activities. Four tests for volleyball skills were conducted: service, overhead, and forearm passing and setting. Additionally, the sport enjoyment questionnaire was used the first and the last week of intervention. Results from repeated measures analysis of variance (ANOVA) showed a significant interaction for overhead passing (F 1, 58 = 5.273, p = 0.025, Partial ƞ² = 0.083) and forearm passing (F 1, 58 = 4.641, p = 0.035, Partial ƞ² = 0.074). When examining the impact of TGfU program on service accuracy, there was a significant main effect for time (p < 0.01) with both groups improving their result after the six-weeks intervention (EXP-ES = 0.32, % change = 9.1% vs. CON-ES = 0.57, % change = 14.4%). There were no significant time or group × time effects for setting (p ˃ 0.05). The EXP group showed significantly better results for enjoyment compared to the CON group (p ≤ 0.05). The findings show the effectiveness of the TGfU model of short duration (12 lessons) in an educational context to improve volleyball skills. We also highlight the importance of enjoyment during these classes compared to traditional physical education classes.

Although neuromuscular training (NMT) emphasizes injury prevention training, there is little information about its effects on performance in young athletes. This study aimed to investigate the effects of eight-weeks NMT on motor competence and physical performance in 10- to 12-year-old female volleyball players. Sixty-six participants (mean ± SD; 11.05 ± 0.72 years) were randomized into either the NMT group (NTG; n = 32) or control group (CON; n = 34). Sprint on 10-m, modified T-test, plank, vertical jump, and medicine ball throw tests were used to assess the physical performance. The Körperkoordinationstest für Kinder (KTK) was used to assess the subjects’ motor competence. The NMT was performed twice a week during the first 30 min of each regularly scheduled 90-minute volleyball training. Participants in the CON group attended only their regular volleyball training. A significant group x time interaction was found for Motor Quotient KTK (MQKTK) (p < 0.001), KTK lateral jumps (p < 0.001), and KTK shifting platforms (p < 0.01). There was a significant interaction for modified T-test results (p < 0.001) and vertical jump (p = 0.04). No change was observed in both groups for plank performance (p > 0.05). The NMT promoted significant gains in motor competence and physical performance in youth female volleyball players.

Studies dealing with the effectiveness of the Fédération Internationale de Football Association (FIFA) 11+ prevention program to improve performance outcomes in children aged < 14 years are limited. This study aimed to point out the effects of the application of short-term FIFA 11+ warm-up program on physical performance in young football players. Participants were 36 youth male football players, divided into a FIFA 11+ (n = 19; mean (SD) age: 11.15 (0.79) y) and a control group (CG: n = 17; age: 10.87 (0.8) y) and trained for 4 weeks. Before and after the training period, standing long jump performance, agility, repeated sprint ability, sit and reach, and “30–15” intermittent fitness tests were assessed. A mixed ANOVA showed significant differences between the groups in the standing long jump test (FIFA 11+: 5.6% vs. CG: −1.9%) in favor of FIFA 11+ over CG. Additionally, the FIFA 11+ performance of the Illinois agility test was significantly better compared to the CG performance (FIFA 11+: −1.9% vs. CG: 0.03%). The main findings of this study suggest that just 4 weeks of implementation of the FIFA 11+ improves physical performance compared with traditional warm-up routines in young soccer players.