Jozef Krizaj

Dr. Jozef Krizaj

University of Ljubljana, Faculty of Sport, Ljubljana, Slovenia
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Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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Krzysztof MackalaKrzysztof Mackala
Krzysztof Mackala
JVJanez Vodicar
Janez Vodicar
MŽMilan Žvan
Milan Žvan
JKJozef Krizaj
Jozef Krizaj
JSJacek Stodolka
Jacek Stodolka
MČMilan Čoh
Milan Čoh
This study assessed differences in agility performance between athletes of team and individual sports by assessing change-of-direction speed (CODS) as pre-planned agility and reactive agility (RA) as non-planed in different spatial configurations. The study involved 36 individual (sprint, hurdles, jumping, tennis, and judo) and 34 team (soccer, basketball, and handball) athletes. CODS and RA were measured with a light-based reactive training system in a frontal (FR), universal (UN), semicircular (SC), and lateral (LA) design. Lower limb power and sprint performance were also measured in a 10 m single leg jump test and 15 m sprint. Individual athletes showed significantly better performance in three of the eight agility tests: LA-RA, UN-RA, and SC-CODS (p < 0.008, p < 0.036, and p < 0.027, respectively) and were found to present stronger correlations (p < 0.01) between jump test performance and the CODS condition. Team athletes showed stronger associations between sprint performance and the CODS condition. In the RA condition both jump and sprint performance showed stronger correlations in the group of individual athletes. Agility performance as measured by CODS and RA should improve with enhanced of motor proficiency. Finally, the tests applied in this experiment seem to be multidimensional, but require spatio-temporal adjustment for their implementation, so that they meet the requirements of the particular sport.

22 January 2020 in Human Movement
Verified
Journal Article
Open access
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JKJozef Krizaj
Jozef Krizaj
Purpose: The general goal of the study was to investigate the relationship between agility t-test (change of direction speed ability, CODS), 20-m sprint test (S20m) (linear speed ability), and countermovement jump (CMJ) test (lower limb explosive power ability).Methods: The sample involved 18 elite female football athletes (age: 18.56 ± 2.24 years, height: 169.47 ± 6.48 cm, weight: 63.52 ± 6.85 kg). Pearson correlation coefficients were applied. Multiple linear regression served to explain the relationship between the dependent variable (CODS) and 2 independent variables (S20m and CMJ).Results: Pearson correlation analysis indicated a moderate relationship between CMJ and CODS performance (r = –0.59, p = 0.01) and a very strong significant relationship between S20m and CODS performance (r = 0.80, p = 0.00). The results of multiple linear regression proved that both independent variables (S20m and CMJ) explained about 60.0% (adjusted R2) of the total model variance in relation to the dependent variable (CODS), whereas only S20m significantly (p < 0.05) explained CODS ability.Conclusions: The study highlighted the impact of explosive power of lower limbs (CMJ) and linear speed capability (S20m) on agility performance (CODS) in our sample. It suggests that the results of agility, linear sprint, and jumping performance seem to have similar determining factors. It is worthwhile to consider these findings in the training process of female elite football players in order to focus on essential training elements of physical fitness.

Krzysztof MackalaKrzysztof Mackala
Krzysztof Mackala
Samo RauterSamo Rauter
Samo Rauter
Jozef SimenkoJozef Simenko
Jozef Simenko
RKRobi Kreft
Robi Kreft
JSJacek Stodolka
Jacek Stodolka
JVJanez Vodicar
Janez Vodicar
The aim of this study was to assess the effect of drop height and selected somatic parameters on the landing kinetics of rebound jumps in force and power production, performed by male and female student athletes. Twenty female and forty male students with a sports background participated in the experiment (mean and standard deviation (± SD): age 20.28 ± 1.31 years, height 166.78 ± 5.29 cm, mass 62.23 ± 7.21 kg and 21.18 ± 1.29, 182.18 ± 6.43, 78.65 ± 7.09). Each participant performed three maximal jumps on two independent and synchronized force platforms (Bilateral Tensiometric Platform S2P) at each of the two assigned drop-jump heights (20-, and 40-, cm for female and 30-, and 60-, cm for the male special platform). Significant between-sex differences were observed in all variables of selected somatics, with men outperforming women. Statistically significant differences were noted in four parameters, between men and women, in both DJs from 20/40 and 30/60 cm. The height of the jump was 6 cm and 4 cm higher for men. A slightly higher statistical significance (p = 0.011) was demonstrated by the relative strength (% BW) generated by the left limb in both men and women. Only women showed a significant relationship between body mass, body height, and five parameters, dropping off of a 20 cm box. In men, only the left leg—relative maximal F (p =−0.45)—showed a relationship with body mass. There were no relationships between the above-mentioned dependencies in both groups, in jumps from a higher height: 40 cm and 60 cm. From a practical application, the DJ with lower 20/30 cm or higher 40/60 cm (women/men) respectively emphasizes either the force or power output via an increase in the velocity component of the rebound action or increased height of the DJ jump.


1 August 2025 in Human Movement
Verified
Journal Article
Closed access
JKJozef Krizaj
Jozef Krizaj
Purpose: The study compared the 30–15 intermittent fitness test (30–15 IFT) and the treadmill-based multistage incremental test to evaluate their effectiveness in assessing cardiorespiratory fitness in elite female football players.Methods: Fifteen Slovenian National A Team female football players (age = 24.4 ± 5.7 years; height = 166.5 ± 6.2 cm; weight = 59.9 ± 6.0 kg) completed the 30–15 IFT and treadmill tests on separate occasions. Maximal running speed (MRS), maximal oxygen consumption (VO2max), and maximum heart rate (HRmax) were measured, with Pearson’s correlation coefficients used to assess their relationships.Results: A moderate positive correlation was found between mean MRS treadmill speed (MRS_Treadmill) and VO2max from the 30–15 IFT (r = 0.533, p = 0.041). The VO2 max from the 30–15 IFT and treadmill test showed a strong correlation (r = 0.756, p = 0.002), while the correlation between treadmill VO2max and mean MRS 30–15 IFT speed (MRS_30–15 IFT) was nearly perfect (r = 0.977, p = 0.000). The intraclass correlation coefficient (ICC ) for single VO2max measurements was 0.689 [95% confidence interval (CI) = 0.271–0.888, p = 0.002], indicating moderate agreement, and 0.816 (95% CI: = 0.426 – 0.941, p = 0.002) for average measurements, indicating strong agreement.Conclusions: These results are important for coaches of elite women’s football. The reduced variability suggests that cardiorespiratory fitness measures are more consistent in elite athletes than in diverse sports populations. This study’s unique contribution lies in its focus on elite national female football players, providing specific findings that enhance the utility of the 30–15 IFT in this specialised context.