Publications by authors named "Miodrag Spasic"

25 Publications

  • Page 1 of 1

Pre-Planned and Non-Planned Agility in Patients Ongoing Rehabilitation after Knee Surgery: Design, Reliability and Validity of the Newly Developed Testing Protocols.

Diagnostics (Basel) 2021 Jan 19;11(1). Epub 2021 Jan 19.

Faculty of Kinesiology, University of Split, 21000 Split, Croatia.

Background: Due to its association with the risk of falling and consequent injury, the importance of agility is widely recognized, but no study so far has examined the different facets of agility in an untrained/clinical population. The aim of this study was to evaluate the reliability, validity, and correlates of newly developed tests of non-planned agility (NPA) and pre-planned agility (PPA) in an untrained/clinical sample.

Methods: The sample comprised 38 participants older than 40 years (22 females, age: 56.1 ± 17.3 years, height: 170.4 ± 10.8 cm, mass: 82.54 ± 14.79 kg) who were involved in a rehabilitation program following total knee arthroplasty and knee arthroscopy. Variables included age, gender, type of surgery, history of fall, anthropometrics/body composition, and newly developed tests of NPA and PPA.

Results: The results showed the high inter-testing- (ICC > 0.95, CV < 9%), and intra-testing-reliability (ICC > 0.96, CV < 9) of the newly developed tests. PPA and NPA were found to be valid in differentiation between age groups (>50 yrs. vs. <50 yrs.), and genders, with better performance in younger participants and males. Only NPA differentiated participants according to type of surgery, with better performance in those who had arthroscopic surgery, than those who had total knee arthroplasty. No differences in NPA and PPA were established between groups based on fall-history. In females, the body mass (Pearson's = 0.58 and 0.59, < 0.001) and body fatness (Pearson's = 0.64 and 0.66, < 0.001) were negatively correlated, while the lean body mass (Pearson's = 0.70 and 0.68, < 0.001) was positively correlated with PPA and NPA. The NPA and PPA were highly correlated (Pearson's = 0.98, < 0.001).

Conclusions: We found that the proposed tests are reliable when evaluating agility characteristics in an untrained/clinical population after knee arthroplasty/arthroscopy. Further evaluation of the specific validity of the proposed tests in other specific subsamples is warranted.
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http://dx.doi.org/10.3390/diagnostics11010146DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7835766PMC
January 2021

Adaptive Control of Nonlinear MIMO System With Orthogonal Endocrine Intelligent Controller.

IEEE Trans Cybern 2022 Feb 16;52(2):1221-1232. Epub 2022 Feb 16.

In this article, a new intelligent hybrid controller is proposed. The controller is based on the combination of the orthogonal endocrine neural network (OENN) and orthogonal endocrine ANFIS (OEANFIS). The orthogonal part of the controller consists of Chebyshev orthogonal functions, which are used because of their recursive property, computational simplicity, and accuracy in nonlinear approximations. Artificial endocrine influence on the controller is achieved by introducing excitatory and inhibitory glands to the OENN part of the structure, in the form of postsynaptic potentials. These potentials provide a network with the capability of additional self-regulation in the presence of external disturbances. The intelligent structure is trained using a developed learning algorithm, which consists of both offline and online learning procedures: online learning for fitting OENN substructure and offline learning for adjusting OEANFIS parameters. The learning process is expanded by introducing the learning rate adaptation algorithm, which bases its calculations on the sign of the error difference. Finally, the proposed intelligent controller was experimentally tested for control of a nonlinear multiple-input-multiple-output two rotor aerodynamical system. During the test phase, an additional four related intelligent control logics and default PID-based controllers were used, and tracking performance comparisons were performed. The proposed controller showed notably better online results in comparison to other control algorithms. The major deficiencies of the structure are complexity and noticeably large training computation time, but these drawbacks can be neglected if tracking performances of a dynamical system are of the highest importance.
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http://dx.doi.org/10.1109/TCYB.2020.2998505DOI Listing
February 2022

Agility Testing in Youth Football (Soccer)Players; Evaluating Reliability, Validity, and Correlates of Newly Developed Testing Protocols.

Int J Environ Res Public Health 2020 01 1;17(1). Epub 2020 Jan 1.

Faculty of Kinesiology, University of Split, 21000 Split, Croatia.

Reactive agility (RAG) and change of direction speed (CODS) are important determinants of success in football (soccer), but there is an evident lack of information on reliable and valid football-specific testing procedures which will be applicable in defining sport-specific RAG and CODS in youth players. This study evaluated reliability and construct validity of newly developed tests of football-specific RAG (FS_RAG) and CODS (FS_CODS), which involved the ball kicking football technique. Additionally, factors associated with FS_RAG and FS_CODS were evaluated. The participants were youth football players (n = 59; age: 13.40 ± 1.25 years) divided according to their age into U13 (11-12 years of age; n = 29), and U15 (13-14 years of age; n = 30) categories. Additionally, performance levels (starters [first-team] vs. non-starters [substitutes]) were observed in each age category. The dependent variables were newly developed FS_RAG and FS_CODS tests. The independent variables were sprinting capacities over 10 and 20 meters (S10M, S20M), countermovement jump (CMJ), the reactive strength index (RSI), and a generic CODS test of 20 yards (20Y). The newly developed FS_CODS and FS_RAG were observed as dependent variables. Results showed appropriate intra-testing and inter-testing reliability of the FS_RAG and FS_CODS, with somewhat better reliability of the FS_CODS (ICC=0.82 and 0.79, respectively). Additionally, better reliability was evidenced in U15 than in U13 (ICC: 0.82-0.85, and 0.78-0.80 for U15 and U13, respectively). Independent samples t-test indicated significant differences between U13 and U15 in S10 (-test: 3.57, < 0.001), S20M (-test: 3.13, < 0.001), 20Y (-test: 4.89, < 0.001), FS_RAG (-test: 3.96, < 0.001), and FS_CODS (-test: 6.42, < 0.001), with better performance in U15. Starters outperformed non-starters in most capacities among U13, but only in FS_RAG among U15 (-test: 1.56, < 0.05). Multiple regression calculations indicated nonsignificant association between independent and dependent variables in U13 (FS_CODS: 19%, FS_RAG: 21% of the explained variance, both > 0.05), but independent variables explained significant proportion of both dependent variables in U15 (FS_CODS: 35%, FS_RAG: 33% explained variance, both < 0.05). The study confirmed the applicability of newly developed tests in distinguishing studied age categories of players. Results indicate that superiority in all studied fitness capacities is translated into performance level in U13. Meanwhile, FS_RAG seems to be important determinant of quality in U15.
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http://dx.doi.org/10.3390/ijerph17010294DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6981745PMC
January 2020

Reliability, Validity and Usefulness of a New Response Time Test for Agility-Based Sports: A Simple vs. Complex Motor Task.

J Sports Sci Med 2019 12 19;18(4):623-635. Epub 2019 Nov 19.

Faculty of Kinesiology, University of Split, Split, Croatia.

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, = 2.40, AUC: 0.98), centre (p < 0.01, = 1.57, AUC: 0.89), and right sensor (p < 0.01, = 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.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6873124PMC
December 2019

Importance of Agility Performance in Professional Futsal Players; Reliability and Applicability of Newly Developed Testing Protocols.

Int J Environ Res Public Health 2019 09 4;16(18). Epub 2019 Sep 4.

University of Split, Faculty of Kinesiology, 21000 Split, Croatia.

The purpose of this study was to determine the inter- and intra-testing reliability of newly developed tests of the change of direction speed (CODS) and reactive agility (RAG) in competitive futsal players. Additionally, the developed tests were evaluated for their validity with regard to the differentiation of two performance-levels. Thirty-two professional male futsal players (age = 26.22 ± 5.22 years; body height = 182.13 ± 5.99 cm, body mass = 77.43 ± 8.00 kg) participated in the study. The sample was divided into two groups based on their level of futsal performance: A top-level-group ( = 12) and a team-level-group ( = 20). The variables included body height, mass, body mass index, a sprint over a 10-m distance (S10M), and eight newly developed futsal specific CODS and RAG tests. The CODS and RAG tests were performed by dribbling the balls (CODS_D and RAG_D) and without dribbling (CODS_T and RAG_T), and the performances on the dominant and non-dominant sides were observed separately. All CODS, and RAG tests performed on dominant side and RAG_T tests performed on the non-dominant side had good inter-testing (CV = 5-8%; ICC = 0.76-0.89) and intra-testing (CV = 4-9%; ICC = 0.77-0.91) reliability. However, RAG_D performed on the non-dominant side was not reliable (ICC = 0.60, CV = 10%). The top-level-players outperformed the team-level-players in the CODS and RAG tests that involved dribbling (-test: 4.28 and 2.40, < 0.05; effect sizes (ES): 0.81 and 1.5, respectively), while the team-level players achieved better results in the CODS_T (-test: 2.08, < 0.05; ES: 0.60). The proposed CODS and RAG tests that involved dribbling over a 3.2-m distance, especially on the dominant side, appeared to be reliable, as well as valid for distinguishing the performance level in futsal players.
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http://dx.doi.org/10.3390/ijerph16183246DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6766010PMC
September 2019

Maturity Status as a Determinant of the Relationships Between Conditioning Qualities and Preplanned Agility in Young Handball Athletes.

J Strength Cond Res 2018 Aug;32(8):2302-2313

Tunisian Research Laboratory "Sports Performance Optimization", National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia.

Hammami, R, Sekulic, D, Selmi, MA, Fadhloun, M, Spasic, M, Uljevic, O, and Chaouachi, A. Maturity status as a determinant of the relationships between conditioning qualities and preplanned agility in young handball athletes. J Strength Cond Res 32(8): 2302-2313, 2018-Studies performed thus far have not accounted for the potential influence of maturity on determinants of preplanned agility. This study aimed to examine how determinants of preplanned agility are affected by the period of peak height velocity (PHV) regarding the anthropometrics and conditioning qualities in young handball players. The sample comprised 56 handball players (male; 12-14 years of age), allocated into 2 groups according to their biological age of maturity: Pre-PHV (N = 34) and Post-PHV (N = 22). Players were evaluated on handball-specific tests of preplanned agility (CODAT and T-HALF). Predictors included anthropometrics, sprinting, horizontal and vertical jumps, and reactive strength index (RSI). The reliability of the tests was appropriate (intraclass correlation coefficient: 0.87-0.95; coefficient of variation: 4.4-5.8%). In the Pre-PHV group, 67% variance of the T-HALF accounted for horizontal countermovement jump (β: -0.83, p < 0.01), 20-m sprint (β: 0.91, p < 0.01), and body mass (β: 0.19, p = 0.02). In the Post-PHV group, 80% of the T-HALF variance was explained, with a significant influence of 20-m sprint (β: 0.52, p < 0.01), RSI (β: -0.24, p = 0.04), and standing long jump (β: -0.57, p = 0.03). In the Pre-PHV group, 45% of the CODAT variance accounted for the partial influence of body fat percentage (β: 0.44, p = 0.04) and a 20-m sprint (β: 0.74, p < 0.01). In the Post-PHV group, the predictors accounted for 79% of the CODAT variance, with a significant influence of the RSI (β: -0.26, p = 0.04) and a 10-m sprint (β: 0.87, p = 0.03). Our results reinforce the need for differential strength and conditioning programs aimed at improving the preplanned agility of young athletes who differ in maturity status.
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http://dx.doi.org/10.1519/JSC.0000000000002390DOI Listing
August 2018

Importance of Reactive Agility and Change of Direction Speed in Differentiating Performance Levels in Junior Soccer Players: Reliability and Validity of Newly Developed Soccer-Specific Tests.

Front Physiol 2018 15;9:506. Epub 2018 May 15.

Faculty of Kinesiology, University of Split, Split, Croatia.

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 the S_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 (-test: 3.61, < 0.05, large ES) and two S_RAG protocols (-test: 2.14 and 2.41, < 0.05, moderate ES). Newly developed tests of soccer-specific agility are applicable to differentiate U17 and U19 players. 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.
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http://dx.doi.org/10.3389/fphys.2018.00506DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5962722PMC
May 2018

The Effects of 3-Month Skill-Based and Plyometric Conditioning on Fitness Parameters in Junior Female Volleyball Players.

Pediatr Exerc Sci 2018 08 24;30(3):353-363. Epub 2018 Feb 24.

5 University of Ljubljana.

Purpose: This study compared the effects of skill-based and plyometric conditioning (both performed in addition to regular volleyball training twice a week for 12 wk) on fitness parameters in female junior volleyball players.

Methods: The participants [n = 47; age: 16.6 (0.6) y; mass: 59.4 (8.1) kg; height: 175.1 (3.0) cm] were randomized into a plyometric (n = 13), a skill-based (n = 17), and a control (n = 17) groups. The variables included body height, body mass, calf girth, calf skinfold, corrected calf girth, countermovement jump, 20-m-sprint, medicine ball toss, and sit-and-reach test.

Results: Two-way analysis of variance (time × group) effects for time were significant (P < .05) for all variables except body mass. Significant group × time interactions were observed for calf skinfold [η = .14; medium effect size (ES)], 20-m sprint (η = .09; small ES), countermovement jump (η = .29; large ES), medicine ball (η = .58; large ES), with greater gains (reduction of skinfold) for plyometric group, and sit-and-reach (η = .35; large ES), with greater gains in plyometric and skill-based groups. The magnitude-based inference indicated positive changes in 1) medicine ball toss and countermovement jump for all groups; 2) sit-and-reach for the plyometric and skill-based groups; and 3) 20-m sprint, calf girth, calf skinfold, and corrected calf girth for plyometric group only.

Conclusion: Selected variables can be improved by adding 2 plyometric training sessions throughout the period of 12 weeks. Additional skill-based conditioning did not contribute to improvement in the studied variables compared with regular volleyball training.
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http://dx.doi.org/10.1123/pes.2017-0178DOI Listing
August 2018

Evaluation of different jumping tests in defining position-specific and performance-level differences in high level basketball players.

Biol Sport 2017 Sep 5;34(3):263-272. Epub 2017 Apr 5.

Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia.

The importance of jumping ability in basketball is well known, but there is an evident lack of studies that have examined different jumping testing protocols in basketball players at advanced levels. The aim of this study was to assess the applicability of different tests of jumping capacity in identifying differences between (i) playing position and (ii) competitive levels of professional players. Participants were 110 male professional basketball players (height: 194.92±8.09 cm; body mass: 89.33±10.91 kg; 21.58±3.92 years of age; Guards, 49; Forwards, 22; Centres, 39) who competed in the first (n = 58) and second division (n = 52). The variables included anthropometrics and jumping test performance. Jumping performances were evaluated by the standing broad jump (SBJ), countermovement jump (CMJ), reactive strength index (RSI), repeated reactive strength ability (RRSA) and four running vertical jumps: maximal jump with (i) take-off from the dominant leg and (ii) non-dominant leg, lay-up shot jump with take-off from the (iii) dominant leg and (iv) non-dominant leg. First-division players were taller (ES: 0.76, 95%CI: 0.35-1.16, moderate differences), heavier (0.69, 0.29-1.10), had higher maximal reach height (0.67, 0.26-1.07, moderate differences), and had lower body fat % (-0.87, -1.27-0.45, moderate differences) than second-division players. The playing positions differed significantly in three of four running jump achievements, RSI and RRSA, with Centres being least successful. The first-division players were superior to second-division players in SBJ (0.63, 0.23-1.03; 0.87, 0.26-1.43; 0.76, 0.11-1.63, all moderate differences, for total sample, Guards, and Forwards, respectively). Running vertical jumps and repeated jumping capacity can be used as valid measures of position-specific jumping ability in basketball. The differences between playing levels in vertical jumping achievement can be observed by assessing vertical jump scores together with differences in anthropometric indices between levels.
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http://dx.doi.org/10.5114/biolsport.2017.67122DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5676323PMC
September 2017

Analyzing the relationship between anthropometric and motor indices with basketball specific pre-planned and non-planned agility performances.

J Sports Med Phys Fitness 2018 Jul-Aug;58(7-8):1037-1044. Epub 2017 May 9.

Faculty for Sport and Physical Education, University of Montenegro, Podgorica, Montenegro.

Background: Although agility is an important quality in basketball, factors associated with basketball specific pre-planned-agility (change-of-direction-speed, CODS) and non-planned-agility (reactive agility, RA) are rarely investigated. The aim of this study was to evaluate relationship between anthropometric and motor indices with basketball-specific CODS and RA in male basketball players of high performance level.

Methods: We tested 88 high-level male basketball players (height: 194.62±8.09 cm; body mass: 89.13±10.81 kg; age: 21.12±3.47 years). The sample was randomly divided into validation (N.=44) and cross-validation (N.=44) subsamples. The study variables included: broad-jump, countermovement-jump, reactive-strength-index, visual-reaction-time, body height, body mass, and body fat percentage (predictors); as well as basketball-specific CODS and RA (criteria). Univariate associations were assessed by Pearson's correlation coefficients. Multivariate relationships between the predictors and the criteria were assessed with multiple regression analysis for the validation subsample, which was then cross-validated.

Results: The established multiple regression models were successfully cross-validated for CODS (R2=0.40 and 0.36; P=0.01) and RA (R2=0.38 and 0.41; P=0.01, for validation and cross-validation subsample, respectively). The broad-jump (i.e., horizontal displacement) is important predictor of CODS (Beta=-0.41; P=0.01); anthropometrics and body build are specifically associated with RA (Beta=0.51, -0.61 and 0.41 for body height, body mass and body fat percentage, respectively; all P<0.05), while reactive-strength-index is directly related both to CODS (Beta=-0.41, P=0.02), and RA (Beta=-0.40, P=0.03).

Conclusions: While basketball players are differentially oriented toward specific game duties, specific capacities should be developed in order to meet specific sport requirements.
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http://dx.doi.org/10.23736/S0022-4707.17.07346-7DOI Listing
October 2018

Reliability and Factorial Validity of Non-Specific and Tennis-Specific Pre-Planned Agility Tests; Preliminary Analysis.

J Hum Kinet 2017 Jan 30;55:107-116. Epub 2017 Jan 30.

University of Ljubljana, Faculty of Sport, Slovenia.

Agility is an important quality in tennis, yet there is an evident lack of studies focussing on the applicability of tennis-specific agility performances and comparing them to equivalent non-specific agility performances. The aim of this study was to evaluate the reliability and factorial validity of three tests of pre-planned agility, performed in specific (with a tennis racquet) and non-specific (without a tennis racquet) conditions. The sample consisted of 33 tennis players (13 males and 20 females; age: 18.3 ± 1.1 years and 18.6 ± 1.3 years; body height: 185.4 ± 51 cm and 169.3 ± 4.2 cm, 74.0 ± 4.4 kg and 61.2 ± 3.1 kg, respectively). The variables comprised three agility tests: a 20-yard test, a T-test and the Illinois test, all performed in both specific and non-specific conditions. Between-subject and within-subject reliability were found to be high (Cronbach Alpha: 0.93 to 0.98; Coefficient of Variation: 3 to 8%), with better within-subject reliability and stability of the measurement for specific tests. Pearson's product moment correlations between the non-specific and specific agility performances were high (r ≥0.84), while factor analysis extracted only one significant latent dimension on the basis of the Guttman-Kaiser criterion. The results of the 20-yard test were better when the test was conducted in the specific conditions (t-test = 2.66; p < 0.05). For the Illinois test, superior results were recorded in the non-specific conditions (t-test = 2.96; p < 0.05), which can be explained by the test duration (about 20 s) and non-specific locomotion forms such as rotational movements. Considering the findings of the present study, when testing tennis-specific pre-planned agility, we suggest using tests of short duration (less than 10 s) and sport-specific types of locomotion.
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http://dx.doi.org/10.1515/hukin-2017-0010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5304279PMC
January 2017

An Examination of the Ethnicity-Specific Prevalence of and Factors Associated with Substance Use and Misuse: Cross-Sectional Analysis of Croatian and Bosniak Adolescents in Bosnia and Herzegovina.

Int J Environ Res Public Health 2016 Sep 29;13(10). Epub 2016 Sep 29.

Faculty of Kinesiology, University of Split, Split 21000, Croatia.

Substance use and misuse (SUM) in adolescence is a significant public health problem and the extent to which adolescents exhibit SUM behaviors differs across ethnicity. This study aimed to explore the ethnicity-specific and gender-specific associations among sports factors, familial factors, and personal satisfaction with physical appearance (i.e., covariates) and SUM in a sample of adolescents from Federation of Bosnia and Herzegovina. In this cross-sectional study the participants were 1742 adolescents (17-18 years of age) from Bosnia and Herzegovina who were in their last year of high school education (high school seniors). The sample comprised 772 Croatian (558 females) and 970 Bosniak (485 females) adolescents. Variables were collected using a previously developed and validated questionnaire that included questions on SUM (alcohol drinking, cigarette smoking, and consumption of other drugs), sport factors, parental education, socioeconomic status, and satisfaction with physical appearance and body weight. The consumption of cigarettes remains high (37% of adolescents smoke cigarettes), with a higher prevalence among Croatians. Harmful drinking is also alarming (evidenced in 28.4% of adolescents). The consumption of illicit drugs remains low with 5.7% of adolescents who consume drugs, with a higher prevalence among Bosniaks. A higher likelihood of engaging in SUM is found among children who quit sports (for smoking and drinking), boys who perceive themselves to be good looking (for smoking), and girls who are not satisfied with their body weight (for smoking). Higher maternal education is systematically found to be associated with greater SUM in Bosniak girls. Information on the associations presented herein could be discretely disseminated as a part of regular school administrative functions. The results warrant future prospective studies that more precisely identify the causality among certain variables.
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http://dx.doi.org/10.3390/ijerph13100968DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5086707PMC
September 2016

Evaluation of Basketball-Specific Agility: Applicability of Preplanned and Nonplanned Agility Performances for Differentiating Playing Positions and Playing Levels.

J Strength Cond Res 2017 Aug;31(8):2278-2288

1Faculty of Kinesiology, University of Split, Split, Croatia; 2Faculty of Natural Sciences Mathematics and Education, University of Mostar, Mostar, Bosnia and Herzegovina; 3Laboratory of Human Performance, Department of Physical Education and Sport, Faculty of Physical Activity and Sport, University of the Basque Country, Vitoria, Spain; and 4Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia.

Sekulic, D, Pehar, M, Krolo, A, Spasic, M, Uljevic, O, Calleja-González, J, and Sattler, T. Evaluation of basketball-specific agility: applicability of preplanned and nonplanned agility performances for differentiating playing positions and playing levels. J Strength Cond Res 31(8): 2278-2288, 2017-The importance of agility in basketball is well known, but there is an evident lack of studies examining basketball-specific agility performances in high-level players. The aim of this study was to determine the reliability and discriminative validity of 1 standard agility test (test of preplanned agility [change-of-direction speed] over T course, T-TEST), and 4 newly developed basketball-specific agility tests, in defining playing positions and performance levels in basketball. The study comprised 110 high-level male basketball players (height: 194.92 ± 8.09 cm; body mass: 89.33 ± 10.91 kg; age: 21.58 ± 3.92 years). The variables included playing position (Guard, Forward, Center), performance level (first division vs. second division), anthropometrics (body height, body mass, and percentage of body fat), T-TEST, nonplanned basketball agility test performed on dominant (BBAGILdom) and nondominant sides (BBAGILnond), and a preplanned (change-of-direction speed) basketball agility test performed on dominant (BBCODSdom) and nondominant sides (BBCODSnond). The reliability of agility tests was high (intraclass correlation coefficient of 0.81-0.95). Forwards were most successful in the T-TEST (F test: 13.57; p = 0.01). Guards outperformed Centers in BBCODSdom, BBCODSndom, BBAGILdom, and BBAGILnond (F test: 5.06, p = 0.01; 6.57, 0.01; 6.26, 0.01; 3.37, 0.04, respectively). First division Guards achieved better results than second division Guards in BBCODSdom (t: 2.55; p = 0.02; moderate effect size differences), BBAGILdom, and BBAGILnond (t: 3.04 and 3.06, respectively; both p = 0.01 and moderate effect size differences). First division Centers outperformed second division Centers in BBAGILdom (t: 2.50; p = 0.02; moderate effect size differences). The developed basketball-specific agility tests are applicable when defining position-specific agility. Both preplanned and nonplanned agilities are important qualities in differentiating between Guards of 2 performance levels. The results confirmed the importance of testing basketball-specific nonplanned agility when evaluating the performance level of Centers.
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http://dx.doi.org/10.1519/JSC.0000000000001646DOI Listing
August 2017

Adaptive PID control based on orthogonal endocrine neural networks.

Neural Netw 2016 Dec 5;84:80-90. Epub 2016 Sep 5.

University of Niš, Faculty of Electronic Engineering, Department of Control Systems, Aleksandra Medvedeva 14, 18000 Niš, Serbia. Electronic address:

A new intelligent hybrid structure used for online tuning of a PID controller is proposed in this paper. The structure is based on two adaptive neural networks, both with built-in Chebyshev orthogonal polynomials. First substructure network is a regular orthogonal neural network with implemented artificial endocrine factor (OENN), in the form of environmental stimuli, to its weights. It is used for approximation of control signals and for processing system deviation/disturbance signals which are introduced in the form of environmental stimuli. The output values of OENN are used to calculate artificial environmental stimuli (AES), which represent required adaptation measure of a second network-orthogonal endocrine adaptive neuro-fuzzy inference system (OEANFIS). OEANFIS is used to process control, output and error signals of a system and to generate adjustable values of proportional, derivative, and integral parameters, used for online tuning of a PID controller. The developed structure is experimentally tested on a laboratory model of the 3D crane system in terms of analysing tracking performances and deviation signals (error signals) of a payload. OENN-OEANFIS performances are compared with traditional PID and 6 intelligent PID type controllers. Tracking performance comparisons (in transient and steady-state period) showed that the proposed adaptive controller possesses performances within the range of other tested controllers. The main contribution of OENN-OEANFIS structure is significant minimization of deviation signals (17%-79%) compared to other controllers. It is recommended to exploit it when dealing with a highly nonlinear system which operates in the presence of undesirable disturbances.
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http://dx.doi.org/10.1016/j.neunet.2016.08.012DOI Listing
December 2016

Outage capacity of FSO link with pointing errors and link blockage.

Opt Express 2016 Jan;24(1):219-30

In this paper, we analyze the outage capacity performance of free-space optical (FSO) systems. More precisely, taking the stochastic temporary blockage of the laser beam, atmospheric turbulence, misalignment between transmitter laser and receiver photodiode and path loss into account, we derive novel accurate analytical expressions for the outage capacity. The intensity fluctuations of the received signal are modeled by a Gamma-Gamma distribution with parameters directly related to the wide range of atmospheric conditions. The analytical results are validated by Monte Carlo simulations. Furthermore, when the intensity fluctuations are caused only by atmospheric turbulence, derived expressions are reduced to the simpler forms already presented in literature. The numerical and simulation results show that the link blockage causes appearance of the outage floor that is a significant energetic characteristic of an FSO system. The results also show that there exists an optimal value of the laser beam radius at the waist for minimizing outage probability in order to achieve the specified outage capacity. This optimal value depends on atmospheric turbulence strength and standard deviation of pointing errors, but it is also strongly dependent on the probability of link blockage.
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http://dx.doi.org/10.1364/OE.24.000219DOI Listing
January 2016

Analysis of the Association Between Motor and Anthropometric Variables with Change of Direction Speed and Reactive Agility Performance.

J Hum Kinet 2015 Sep 14;47:137-45. Epub 2015 Oct 14.

University of Ljubljana, Faculty of Sport, Slovenia.

There is an evident lack of studies examining the factors associated with reactive agility performances. The aim of this study was to evaluate the association between anthropometrics, body composition, jumping capacity, reactive strength, and balance with a stop-and-go change of direction speed (CODS) and reactive agility. The total sample comprised 39 male (body height: 182.95 ± 5.19 cm; body mass: 80.66 ± 7.69 kg) and 34 female (body height: 171.45 ± 6.81 cm; body mass: 61.95 ± 6.70 kg) college-level athletes (21.9 ± 1.9 years of age). The variables included body height, body mass, the percentage of body fat (BF%), balance as measured by an overall-stability index, the countermovement jump (CMJ), a reactive-strength index (RSI), stop-and-go reactive agility, and stop-and-go CODS. To define the associations between motor and anthropometric variables with CODS and reactive agility, the participants were clustered into three achievement groups based on their CODS and reactive agility performances. The ANOVA showed a significant difference between the CODS-based achievement groups for the CMJ (F test = 3.45 and 3.60 for males and females, respectively; p < 0.05), the RSI (F test = 6.94 and 5.29 for males and females, respectively; p < 0.05), and balance (F test = 3.47; p < 0.05 for males). In females, the reactive agility achievement groups differed significantly in the RSI (F test = 6.46; p < 0.05), the CMJ (F test = 4.35; p < 0.05) and BF% (F test = 4.07; p < 0.05), which is further confirmed by discriminant canonical analysis (Can R = 0.74; p < 0.05). The results confirm the need for independent evaluation and training for both CODS and reactive agility performance in sports.
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http://dx.doi.org/10.1515/hukin-2015-0069DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4633249PMC
September 2015

Reactive Agility Performance in Handball; Development and Evaluation of a Sport-Specific Measurement Protocol.

J Sports Sci Med 2015 Sep 11;14(3):501-6. Epub 2015 Aug 11.

University of Split , Faculty of Kinesiology, Croatia.

There is no current study that examined sport-specific tests of reactive-agility and change-of-direction-speed (CODS) to replicate real-sport environment in handball (team-handball). This investigation evaluated the reliability and validity of two novel tests designed to assess reactive-agility and CODS of handball players. Participants were female (25.14 ± 3.71 years of age; 1.77 ± 0.09 m and 74.1 ± 6.1 kg) and male handball players (26.9 ± 4.1 years of age; 1.90 ± 0.09 m and 93.90±4.6 kg). Variables included body height, body mass, body mass index, broad jump, 5-m sprint, CODS and reactive-agility tests. Results showed satisfactory reliability for reactive-agility-test and CODS-test (ICC of 0.85-0.93, and CV of 2.4-4.8%). The reactive-agility and CODS shared less than 20% of the common variance. The calculated index of perceptual and reactive capacity (P&RC; ratio between reactive-agility- and CODS-performance) is found to be valid measure in defining true-game reactive-agility performance in handball in both genders. Therefore, the handball athletes' P&RC should be used in the evaluation of real-game reactive-agility performance. Future studies should explore other sport-specific reactive-agility tests and factors associated to such performance in sports involving agile maneuvers. Key pointsReactive agility and change-of-direction-speed should be observed as independent qualities, even when tested over the same course and similar movement templateThe reactive-agility-performance of the handball athletes involved in defensive duties is closer to their non-reactive-agility-score than in their peers who are not involved in defensive dutiesThe handball specific "true-game" reactive-agility-performance should be evaluated as the ratio between reactive-agility and corresponding CODS performance.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4541112PMC
September 2015

Gender-Specific Analyses of the Prevalence and Factors Associated with Substance Use and Misuse among Bosniak Adolescents.

Int J Environ Res Public Health 2015 Jun 10;12(6):6626-40. Epub 2015 Jun 10.

Faculty of Kinesiology, University of Split, Teslina 6, Split-21000, Croatia.

Ethnicity and religion are known to be important factors associated with substance use and misuse (SUM). Ethnic Bosniaks, Muslims by religion, are the third largest ethnic group in the territory of the former Yugoslavia, but no study has examined SUM patterns among them. The aim of this study was to explore the prevalence of SUM and to examine scholastic-, familial- and sport-factors associated with SUM in adolescent Bosniaks from Bosnia-and-Herzegovina. The sample comprised 970 17-to-18-year-old adolescents (48% boys). Testing was performed using an previously validated questionnaire investigating socio-demographic-factors, scholastic-variables, and sport-factors, cigarette smoking, alcohol drinking, simultaneous smoking and drinking (multiple SUM), and the consumption of other drugs. The 30% of boys and 32% of girls smoke (OR=1.13; 95% CI=0.86-1.49), 41% of boys and 27% of girls are defined as harmful alcohol drinkers (OR=1.94; 95% CI=1.48-2.54), multiple SUM is prevalent in 17% of boys and 15% of girls (OR=1.11; 95% CI=0.79-1.56), while the consumption of other drugs, including sedatives, is higher in girls (6% and 15% for boys and girls, respectively; OR=2.98; 95% CI=1.89-4.70). Scholastic achievement is negatively associated with SUM. SUM is more prevalent in those girls who report higher income, and boys who report a worse familial financial situation. The study revealed more negative than positive associations between sport participation and SUM, especially among girls. Results can help public health authorities to develop more effective prevention campaign against SUM in adolescence.
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http://dx.doi.org/10.3390/ijerph120606626DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4483720PMC
June 2015

Agility performance in high-level junior basketball players: the predictive value of anthropometrics and power qualities.

J Sports Med Phys Fitness 2016 Jul-Aug;56(7-8):884-93. Epub 2015 May 5.

Faculty of Kinesiology, University of Split, Split, Croatia -

Background: In basketball, anthropometric status is an important factor when identifying and selecting talents, while agility is one of the most vital motor performances. The aim of this investigation was to evaluate the influence of anthropometric variables and power capacities on different preplanned agility performances.

Methods: The participants were 92 high-level, junior-age basketball players (16-17 years of age; 187.6±8.72 cm in body height, 78.40±12.26 kg in body mass), randomly divided into a validation and cross-validation subsample. The predictors set consisted of 16 anthropometric variables, three tests of power-capacities (Sargent-jump, broad-jump and medicine-ball-throw) as predictors. The criteria were three tests of agility: a T-Shape-Test; a Zig-Zag-Test, and a test of running with a 180-degree turn (T180). Forward stepwise multiple regressions were calculated for validation subsamples and then cross-validated. Cross validation included correlations between observed and predicted scores, dependent samples t-test between predicted and observed scores; and Bland Altman graphics.

Results: Analysis of the variance identified centres being advanced in most of the anthropometric indices, and medicine-ball-throw (all at P<0.05); with no significant between-position-differences for other studied motor performances. Multiple regression models originally calculated for the validation subsample were then cross-validated, and confirmed for Zig-zag-Test (R of 0.71 and 0.72 for the validation and cross-validation subsample, respectively). Anthropometrics were not strongly related to agility performance, but leg length is found to be negatively associated with performance in basketball-specific agility. Power capacities are confirmed to be an important factor in agility.

Conclusions: The results highlighted the importance of sport-specific tests when studying pre-planned agility performance in basketball. The improvement in power capacities will probably result in an improvement in agility in basketball athletes, while anthropometric indices should be used in order to identify those athletes who can achieve superior agility performance.
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March 2017

Isokinetic knee strength qualities as predictors of jumping performance in high-level volleyball athletes: multiple regression approach.

J Sports Med Phys Fitness 2016 Jan-Feb;56(1-2):60-9. Epub 2014 Nov 25.

Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia -

Background: Previous investigations noted potential importance of isokinetic strength in rapid muscular performances, such as jumping. This study aimed to identify the influence of isokinetic-knee-strength on specific jumping performance in volleyball. The secondary aim of the study was to evaluate reliability and validity of the two volleyball-specific jumping tests.

Methods: The sample comprised 67 female (21.96±3.79 years; 68.26±8.52 kg; 174.43±6.85 cm) and 99 male (23.62±5.27 years; 84.83±10.37 kg; 189.01±7.21 cm) high- volleyball players who competed in 1st and 2nd National Division. Subjects were randomly divided into validation (N.=55 and 33 for males and females, respectively) and cross-validation subsamples (N.=54 and 34 for males and females, respectively). Set of predictors included isokinetic tests, to evaluate the eccentric and concentric strength capacities of the knee extensors, and flexors for dominant and non-dominant leg. The main outcome measure for the isokinetic testing was peak torque (PT) which was later normalized for body mass and expressed as PT/Kg. Block-jump and spike-jump performances were measured over three trials, and observed as criteria. Forward stepwise multiple regressions were calculated for validation subsamples and then cross-validated. Cross validation included correlations between and t-test differences between observed and predicted scores; and Bland Altman graphics.

Results: Jumping tests were found to be reliable (spike jump: ICC of 0.79 and 0.86; block-jump: ICC of 0.86 and 0.90; for males and females, respectively), and their validity was confirmed by significant t-test differences between 1st vs. 2nd division players. Isokinetic variables were found to be significant predictors of jumping performance in females, but not among males. In females, the isokinetic-knee measures were shown to be stronger and more valid predictors of the block-jump (42% and 64% of the explained variance for validation and cross-validation subsample, respectively) than that of the spike-jump (39% and 34% of the explained variance for validation and cross-validation subsample, respectively). Differences between prediction models calculated for males and females are mostly explained by gender-specific biomechanics of jumping.

Conclusions: Study defined importance of knee-isokinetic-strength in volleyball jumping performance in female athletes. Further studies should evaluate association between ankle-isokinetic-strength and volleyball-specific jumping performances. Results reinforce the need for the cross-validation of the prediction-models in sport and exercise sciences.
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September 2016

Predicting agility performance with other performance variables in pubescent boys: a multiple-regression approach.

Percept Mot Skills 2014 Apr;118(2):447-61

The goal was to investigate the influence of balance, jumping power, reactive-strength, speed, and morphological variables on five different agility performances in early pubescent boys (N = 71). The predictors included body height and mass, countermovement and broad jumps, overall stability index, 5 m sprint, and bilateral side jumps test of reactive strength. Forward stepwise regressions calculated on 36 randomly selected participants explained 47% of the variance in performance of the forward-backward running test, 50% of the 180 degrees turn test, 55% of the 20 yd. shuttle test, 62% of the T-shaped course test, and 44% of the zig-zag test, with the bilateral side jumps as the single best predictor. Regression models were cross-validated using the second half of the sample (n = 35). Correlation between predicted and achieved scores did not provide statistically significant validation statistics for the continuous-movement zig-zag test. Further study is needed to assess other predictors of agility in early pubescent boys.
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http://dx.doi.org/10.2466/25.10.PMS.118k16w4DOI Listing
April 2014

The development of a new stop'n'go reactive-agility test.

J Strength Cond Res 2014 Nov;28(11):3306-12

1Faculty of Kinesiology, University of Split, Split, Croatia; and 2University Department of Health Care Studies, University of Split, Split, Croatia.

The main objective of this study was to evaluate the reliability and the validity of a newly constructed reactive-agility test that can be used to define the reactive-agility performance in sports that employ repeated scenarios of "stop'n'go" agility. Measuring is done by original hardware based on the ATMEL microcontroller AT89C51RE2. A total of 36 college-aged male athletes (age, 22.1 ± 2.4 years; body height, 182.45 ± 5.19 cm; body mass, 80.67 ± 7.69 kg) and 21 college-aged female athletes (age, 21.4 ± 2.5 years; body height, 171.45 ± 6.81 cm; body mass, 61.95 ± 6.70 kg) were evaluated for a stop'n'go reactive-agility test (SNG-RAT), stop'n'go change of direction speed (SNG-CODS), countermovement jump, and anthropometrics. The reliability analyses suggested a high consistency for the applied tests (SNG-CODS, intraclass correlation coefficient [ICC] = 0.87 and 0.92; SNG-RAT, ICC = 0.81 and 0.86, for men and women, respectively). The SNG-RAT and SNG-CODS shared <40% of the common variance. The longer version of the SNG-RAT, which included 5 unpredictable changes of direction, was found to be valid among men. At the same time, the shorter version of the SNG-RAT (3 unpredictable changes of direction) is suggested for women because it better discriminates more agile from less agile athletes. Because the SNG-RAT and SNG-CODS were performed on the same course, we believe that simultaneously performing both tests can be beneficial when defining "stop'n'go" agility. This implies that the calculated SNG-CODS to SNG-RAT ratio will allow strength and conditioning coaches to indirectly determine the perceptual and reaction capacities of their athletes.
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http://dx.doi.org/10.1519/JSC.0000000000000515DOI Listing
November 2014

Sport-specific and anthropometric factors of quality in junior male water polo players.

Coll Antropol 2013 Dec;37(4):1261-6

University of Split, Faculty of Kinesiology, Split, Croatia.

There is evident lack of studies which examined anthropological determinants of success in water polo. The aim of this investigation was to study the physical fitness differences between two qualitative levels of junior water polo players (males; 16-18 years of age; 6+ year of experience in water polo). The sample (N = 54) comprised of 13 members of the junior national-squad (5 centers and 8 perimeter players), and 41 team-athletes (11 centers and 30 perimeter players). The sample of variables included: four anthropometric measures (body height, body mass, BMI and body fat percentage), and five sport-specific fitness tests (20-meters-sprint-swimming, maximal dynamometric force in eggbeater kick, in-water vertical jump, drive-shoot-speed, and sport-swimming-endurance). Discriminant analysis and t-test revealed no significant differences between national-squad and team-players for center players. The national-squad perimeters were advanced over their team-level peers in most of the fitness capacities and body-height. The result highlights the necessity of the playing-position-specific approach in defining anthropological factors of success in team-sports.
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December 2013

Sport-specific motor fitness tests in water polo: reliability, validity and playing position differences.

J Sports Sci Med 2013 1;12(4):646-54. Epub 2013 Dec 1.

Faculty of Kinesiology, University of Split , Teslina 6, Split, Croatia ;

Sport-specific motor fitness tests are not often examined in water polo. In this study we examined the reliability, factorial and discriminative validity of 10 water-polo-specific motor-fitness tests, namely: three tests of in-water jumps (thrusts), two characteristic swimming sprints (10 and 20 metres from the water start), three ball-throws (shoots), one test of passing precision (accuracy), and a test of the dynamometric force produced while using the eggbeater kick. The sample of subjects consisted of 54 young male water polo players (15 to 17 years of age; 1.86 ± 0.07 m, and 83.1 ± 9.9 kg). All tests were applied over three testing trials. Reliability analyses included Cronbach Alpha coefficients (CA), inter-item- correlations (IIR) and coefficients of the variation (CV), while an analysis of variance was used to define any systematic bias between the testing trials. All tests except the test of accuracy (precision) were found to be reliable (CA ranged from 0.83 to 0.97; IIR from 0.62 to 0.91; CV from 2% to 21%); with small and irregular biases between the testing trials. Factor analysis revealed that jumping capacities as well as throwing and sprinting capacities should be observed as a relatively independent latent dimensions among young water polo players. Discriminative validity of the applied tests is partially proven since the playing positions significantly (p < 0.05) differed in some of the applied tests, with the points being superior in their fitness capacities in comparison to their teammates. This study included players from one of the world's best junior National leagues, and reported values could be used as fitness standards for such an age. Further studies are needed to examine the applicability of the proposed test procedures to older subjects and females. Key PointsHere presented and validated sport specific water polo motor fitness tests are found to be reliable in the sample of young male water polo players.Factor analysis revealed existence of three inde-pendent latent motor dimensions, namely, in-water jumping capacity, throwing ability, and sprint swimming capacity.Points are found to be most advanced in their fitness capacities which are mainly related to their game duties which allowed them to develop variety of fit-ness components.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3873654PMC
January 2014

Gender-specific influences of balance, speed, and power on agility performance.

J Strength Cond Res 2013 Mar;27(3):802-11

University of Split, Split, Croatia.

The quick change of direction (i.e., agility) is an important athletic ability in numerous sports. Because of the diverse and therefore hardly predictable manifestations of agility in sports, studies noted that the improvement in speed, power, and balance should result in an improvement of agility. However, there is evident lack of data regarding the influence of potential predictors on different agility manifestations. The aim of this study was to determine the gender-specific influence of speed, power, and balance on different agility tests. A total of 32 college-aged male athletes and 31 college-aged female athletes (age 20.02 ± 1.89 years) participated in this study. The subjects were mostly involved in team sports (soccer, team handball, basketball, and volleyball; 80% of men, and 75% of women), martial arts, gymnastics, and dance. Anthropometric variables consisted of body height, body weight, and the body mass index. Five agility tests were used: a t-test (T-TEST), zig-zag test, 20-yard shuttle test, agility test with a 180-degree turn, and forward-backward running agility test (FWDBWD). Other tests included 1 jumping ability power test (squat jump, SQJ), 2 balance tests to determine the overall stability index and an overall limit of stability score (both measured by Biodex Balance System), and 2 running speed tests using a straight sprint for 10 and 20 m (S10 and S20, respectively). A reliability analysis showed that all the agility tests were reliable. Multiple regression and correlation analysis found speed and power (among women), and balance (among men), as most significant predictors of agility. The highest Pearson's correlation in both genders is found between the results of the FWDBWD and S10M tests (0.77 and 0.81 for men and women, respectively; p < 0.05). Power, measured using the SQJ, is significantly (p < 0.05) related to FWDBWD and T-TEST results but only for women (-0.44; -0.41). The balance measures were significantly related to the agility performance for men but not for women. In addition to demonstrating a known relationship between speed and agility in both genders, and a small but statistically significant relationship between power and agility in women, these results indicate that balance should be considered as a potential predictor of agility in trained adult men.
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http://dx.doi.org/10.1519/JSC.0b013e31825c2cb0DOI Listing
March 2013
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