Mid Sweden University

The purpose of this study was to establish the validity, reliability, and usefulness of a low-cost contact mat equipment (CM) with a force plate (FP) as the reference. Eleven female (18.6 ± 3.67 yrs.) and male (18.2 ± 2.71 yrs.) basketball athletes performed hands-on-waist countermovement jump (CMJ) and squat jump (SJ) trials. Flight time (FT) and jump height (JH) in CMJ and SJ were subjected for analysis. Relative error expressed as percentage (%RE) was utilized to examine criterion validity between CM and FP. Concurrent validity was also established using Pearson moment correlation (r). Absolute reliability was determined using coefficient of variation (%CV). Relative reliability was identified using intra-class correlation coefficient (ICC). Usefulness was established by comparing typical error (TE) vs. smallest worthwhile change (SWC). Results revealed that CMJ and SJ from a low-cost CM can be used as an alternative tool in assessment of jump performance.

Background: This study aimed to investigate the accuracy and reliability of a free mobile heart rate variability (HRV) application in measuring HRV. Methods: Twelve females and 12 males underwent five-minute simultaneous HRV recording from electrocardiogram (ECG) and chest strap connected to a free mobile HRV application (HRVapp) in a supine position. HRV data from ECG and HRVapp were used to examine accuracy and reliability via relative error and intraclass correlation coefficient respectively. Results: The natural log of the square root of the mean of the sum of the squares of differences between adjacent normal to normal intervals (lnRMSSD) exhibited accuracy and high reliability in HRVapp. Conclusion: lnRMSSD in HRVapp can serve as an alternative, low-cost technology for measurement of autonomic activity.

The importance of response time (RT) in sports is well known, but there is an evident lack of reliable and valid sport-specific measurement tools applicable in the evaluation of RT in trained athletes. This study aimed to identify the validity, reliability, and usefulness of four newly developed RT testing protocols among athletes from agility-saturated (AG) and non-agility-saturated (NAG) sports. Thirty-seven AG and ten NAG athletes (age: 20.9 ± 2.9; eleven females) volunteered to undergo: three randomized simple response time (SRT-1, SRT-2, and SRT-3) protocols that included a single limb movement, and one complex response time (CRT) protocol that included multi joint movements and whole body transition over a short distance (1.5 and 1.8m). Each RT test involved 3 trials with 5 randomized attempts per trial. Two sensors were placed at the left-and right-hand side for SRT-1 and SRT-2. Three sensors were positioned (left, middle, right) in SRT-3 and CRT. The intra-class-correlation coefficient (ICC) was calculated as a measure of reliability. Independent sample t-test, effect size (d), and area-under-the-curve (AUC) were calculated to define discriminative validity of the tests. The results showed the newly developed tests were more reliable and useful in the AG than NAG athletes (i.e., ICC between 0.68 and 0.97 versus 0.31-0.90, respectively). The RT of AG athletes was faster than that of NAG athletes in the CRT test from the left (p <0.01, d = 2.40, AUC: 0.98), centre (p < 0.01, d = 1.57, AUC: 0.89), and right sensor (p < 0.01, d = 1.93, AUC: 0.89) locations. In contrast, there were no differences between the groups in the SRT tests. The weak correlation (i.e., r= 0.00-0.33) between the SRT and CRT tests suggests that response time of the single limb and multijoint limb movements should not be considered as a single motor capacity. In conclusion, this study showed that AG athletes had faster response time than their NAG peers during complex motor tasks. Such enhanced ability to rapidly and accurately reprogram complex motor tasks can be considered one of the essential qualities required for advanced performance in agility-based sports. 

The purpose of this article was to perform a systematic review and meta-analysis on the effect of contrast training (CT) On vertical jump performance. Thirteen of 83 studies were included for systematic review, whereas 10 studies were used for meta-analysis. Meta-analysis revealed greater countermovement jump (CMJ) gains in CT than in resistance training (RT) (Effect Size [ES] = 1.30; confidence interval [CI] = 0.31-2.30). Similarly, CT displayed higher CMJ than control (ES = 1.46; CI = 0.46-2.46). In conclusion, CT showed greater improvement in CMJ compared with RT and CON. For a video abstract of this article, see video, supplemental digital content 1, Http://LINKS.LWW.COM/SCJ/A247. 

Background: This study aimed to prospectively investigate the scholastic factors related to illicit drug misuse (IDM) and the initiation of IDM among older adolescents from Bosnia andHerzegovina. Methods: This 2-year prospective study included 436 participants (202 females), who were an average of 16 years old at the beginning of the study (baseline). The participants were tested at baseline and follow-up (20 months later). The predictors included variables of scholastic-achievement (grade point average, school absences, unexcused absences and behavioral grade). The criteria were: (i) IDM at baseline; (ii) IDM at follow-up; and (iii) initiation of IDM over the study course. Results: Logistic regression indicated increased odds of IDM in adolescents who were more frequent absent from school (baseline: Odds Ratio (OR): 3.73, 95% Confidence Interval (CI): 2.12–6.57; follow-up: OR: 2.91, 95% CI: 1.90–4.65). The lower grade point average and more unexcused absences were evidenced for adolescents who consumed drugs on follow-up(OR: 1.67, 95% CI: 1.11–2.51; OR: 1.74, 95% CI: 1.30–2.32 for grade point average and unexcused absences, respectively). Initiation of IDM was predicted by frequent absences from school (OR: 2.2,95% CI: 1.3–3.8), and lower behavioral grades (OR: 1.9, 95% CI: 1.2–3.3). Conclusions: The findings confirmed strong correlations between scholastic failure and IDM. Absences from school and lower behavioral grades at baseline were predictive of the initiation of IDM in older adolescents.

Sport participation is considered as a factor of potential influence on illicit drugmisuse (IDM) in adolescence, but there is an evident lack of studies which prospectively investigated this problem. This study aimed to prospectively investigate the sports-related factors related to IDM and the initiation of IDM among older adolescents. The participants were 436 adolescents (202 females; 16 years old at study baseline). They were tested at baseline and follow-up (two years later). The predictors included variables associated with different facets of sports participation and success in sports. The criteria were (i) baseline IDM, (ii) follow-up IDM, and (iii) initiation of IDM between baseline and follow-up. Crude and adjusted (controlled for parental conflict, age, socioeconomic status, and gender) logistic regressions were applied to establish correlations between predictors and criteria. There were higher odds for baseline IDM in adolescents who quit individual sports (OR: 4.2, 95% CI: 1.3-13.9), who had better competitive sports achievements (OR: 1.8, 95% CI: 1.0-3.3), and those involved in sports for a longer time (OR: 1.6, 95% CI: 1.0-2.5). The IDM at follow-up was more prevalent in adolescents who were involved in sports for a longer time (OR: 1.7, 95% CI: 1.1-2.6). Initiation of drug use was predicted by longer experience in sports (OR: 1.8, 95% CI: 1.1-3.1). Sports-related factors were more negatively than positively related to illicit drug use. Most probably, the transition from junior to senior level in sports put specific stress on those adolescents who were highly committed to sports until that time, but who then had to question their own sports abilities and future potential in sports. Sport-authorities should be informed on established results and specific public-health efforts aimed at preventing IDM in athletic adolescents are urgently needed.

Little is known about the influence of conditioning capacities on shooting performance in basketball. The aim of this study was to examine the relationship between different conditioning capacities and shooting performance in professional basketball players. In this investigation, we examined 38 males (all perimeter players; height: 185.5+/-6.73 cm; mass: 78.66+/-10.35 kg). Conditioning capacities were evaluated by tests of muscular-strength, aerobic-endurance, jumping- and throwing-capacities, sprinting-speed, pre-planned-agility, anaerobic-endurance and fatigue-resistance. Shooting performance was evaluated using game statistics, as well as six tests of shooting-performance performed in controlled settings: (i) three tests of static (i.e., non-fatigued) shooting-performance (standardized execution of one- (S1), two- (S2) and three-point shots (S3) in stationary conditions), and (ii) three tests of dynamic (i.e., fatigued) shooting-performance (standardized execution of one- (D1), two- (D2), and three-point shots (D3) in dynamic conditions). All three dynamic shooting tests and the S1 test were significantly (p<0.05) correlated with corresponding game statistics. Multiple regression indicated that conditioning capacities were significantly related to D1 (R2=0.36; p=0.03), D2 (R2=0.44; p=0.03), S3 (R2=0.41; p=0.02) and D3 (R2=0.39; p=0.03) tests. Players with a higher fatigue-resistance achieved better results on D1 test ([beta]=-0.37, p=0.03). Pre-planned-agility ([beta]=-0.33, p=0.04), countermovement jump ([beta]=0.42, p=0.03) and fatigue-resistance ([beta]=-0.37, p=0.02) were significant predictors of D2 performance. The countermovement jump ([beta]=0.39, p=0.04), medicine ball toss ([beta]=0.34, p=0.04) and anaerobic-endurance ([beta]=0.46, p=0.04) predicted the results of D3 performance. Jumping, throwing and anaerobic endurance capacities were good determinants of the skill of dynamic shooting over a long distance. These findings emphasize the importance of explosive power and anaerobic-capacity as determinants of shooting-performance in high-level basketball players.

Agility is a significant determinant of success in soccer; however, studies have rarely presented and evaluated soccer-specific tests of reactive agility (S_RAG) and non-reactive agility (change of direction speed – S_CODS) or their applicability in this sport. The aim of this study was to define the reliability and validity of newly developed tests of the S_RAG and S_CODS to discriminate between the performance levels of junior soccer players. The study consisted of 20 players who were involved at the highest national competitive rank (all males; age: 17.0 0.9 years), divided into three playing positions (defenders, midfielders, and forwards) and two performance levels(U17 and U19). Variables included body mass (BM), body height, body fat percentage,20-m sprint, squat jump, countermovement jump, reactive-strength-index, unilateral jump, 1RM-back-squat, S_CODS, and three protocols of S_RAG. The reliabilities of theS_RAG and S_CODS were appropriate to high (ICC: 0.70 to 0.92), with the strongest reliability evidenced for the S_CODS. The S_CODS and S_RAG shared 25–40% of the common variance. Playing positions significantly differed in BM (large effect-size differences [ES]; midfielders were lightest) and 1RM-back-squat (large ES; lowest results in midfielders). The performance levels significantly differed in age and experience in soccer; U19 achieved better results in the S_CODS (t-test: 3.61, p < 0.05, large ES)and two S_RAG protocols (t-test: 2.14 and 2.41, p < 0.05, moderate ES). Newly developed tests of soccer-specific agility are applicable to differentiate U17 and U19players. Coaches who work with young soccer athletes should be informed that the development of soccer-specific CODS and RAG in this age is mostly dependent on training of the specific motor proficiency.

This study aimed to examine: (i) the level of physical activity (PA), obesity indices and cardiorespiratory fitness (CRF) among boys and girls in primary school, and (ii) to determine the association of obesity indices and PA with CRF for the total number of participants, and then separately for boys and girls. 753 sixth to ninth grade girls and boys aged 10-14 years took part in this cross-sectional study. The PA was assessed by the "Physical Activity Questionnaire - Children" and CRF was assessed by the Maximal multistage a 20 m shuttle run test. Body mass index (BMI), waist circumferences (WC), and waist to height ratio (WHtR) were considered as obesity indices. Multiple linear regression analyses were performed to explore correlates of CRF. The results obtained showed the prevalence of general overweight and obesity was 25.5% in our sample which was lower than that in the regional estimate (e.g., similar to 28%) for Eastern Europe. Among all participants, CRF was associated with male sex, older age, a lower WC percentile, higher WHtR, and higher level of PA. The model accounted for 24% of the variance. CRF was associated with older age and higher level of PA among girls and boys. Lower WC percentile was a significant determinant of CRF among boys. In conclusion, general overweight/obesity was not independently associated with CRF. Those with better CRF were more likely to be male and older, had a higher level of PA and lower central adiposity. These findings emphasize the importance of supporting school age children to take a part in programmed physical activity regardless of their body composition.

Purpose: Non-planned agility (reactive agility - RAG), and pre-planned agility (change of direction speed- CODS) are important determinants of success in basketball. However, the association between these two conditioning capacities in high-level basketball players is rarely evidenced. The aim of this investigation was to evaluate the relationship between basketball-specific CODS and RAG in the total sample, and separately for three main playing positions in the game of basketball (i.e. guards, forwards and centers).

Methods: The sample comprised 106 national/international-level male basketball players (age:21.9±3.5 years; body height: 195.1±7.9 cm; body mass: 90.1±10.0 kg), divided according to their playing positions in game (guards, N = 49; forwards, N = 22; centers, N = 35). The variables included body mass, body height, and body fat percentage; as well as basketball-specific CODS and -RAG. The reliability of CODS and RAG was evidenced by intra-class-coefficients (ICC). Differences among positions were established by one-way analysis of variance, consecutive post-hoc analyses, and effect size differences (η2). Finally, the relationship between variables was established by means of Pearson’s moment correlation coefficient (r), which was calculated for the total sample, and then separately for each playing position.

Results: The intra-session reliability was somewhat higher for CODS, than for RAG (ICC: 0.81 and 0.76, respectively). The centers were tallest (F: 67.75, p < 0.01; η2: 0. 57), and heaviest (F: 39.01, p < 0.01,η2: 0.44), followed by forwards. The guards and forwards achieved better results than centers in CODS(F: 5.19, p < 0.01; η2: 0.09), and RAG (F: 3.85, p < 0.05; E η2: 0.07). When observed for the total sample, the CODS and RAG shared 49% of common variance (r: 0.70). When calculated for playing positions, the highest correlation between CODS and RAG was evidenced for centers (r: 0.81), then for forwards(r: 0.71), and guards (r: 0.51).

Conclusion: Relatively strong correlations between CODS and RAG among forwards and centers implies the possibility of simultaneous strength and conditioning of these capacities for these two playing positions. Meanwhile, because of the small common variance, separate training for RAG and CODS is warranted for guards. The study highlights the necessity of a position-specific approach to evidencing determinants of sport-specific conditioning qualities for high-level players.