Lazaros Vardakis

Dr. Lazaros Vardakis

SEFAA, Aristotle University of Thessaloniki, Thessaloníki, Kentrikí Makedonía, Greece
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Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

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

Representative Publications

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Journal Article
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Andreas StafylidisAndreas Stafylidis
Andreas Stafylidis
Athanasios MandroukasAthanasios Mandroukas
Athanasios Mandroukas
Yiannis MichailidisYiannis Michailidis
Yiannis Michailidis
Lazaros VardakisLazaros Vardakis
Lazaros Vardakis
IMIoannis Metaxas
Ioannis Metaxas
TMThomas Metaxas
Thomas Metaxas
Previous research emphasizes the significance of key performance metrics in determining match outcomes. The purpose of this study is to enhance the understanding of success in professional soccer by analyzing the relationship between match outcomes (win, lose, draw) and various Performance Indicators extracted from the Greek soccer league, as well as to develop a regression model of success in soccer. The sample consisted of all 91 matches from the first round of the 2020–2021 season of the Greek Football League. Utilizing Kruskal–Wallis tests, significant differences were found in goals scored, shots, and shots on target, ball possession, passing metrics, touches in the penalty area, and average shot distance (p < 0.05), with winning teams having demonstrated superior performance metrics. Moreover, winning teams engaged more in positional attacks and counterattacks with shots (p < 0.05). The binary logistic regression model applied to predict match outcomes identified shots on target, counterattacks, passes metrics, offensive duels and set pieces (penalties, free kicks) as key factors influencing the likelihood of winning (p < 0.05). These findings collectively highlight the importance of effective offensive play, including goal scoring, shooting accuracy, and ball possession, in determining the outcomes of soccer matches, with the regression model offering a nuanced understanding of these relationships.

4 December 2019 in German Journal of Exercise and Sport Research
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Lazaros VardakisLazaros Vardakis
Lazaros Vardakis
Yiannis MichailidisYiannis Michailidis
Yiannis Michailidis
Athanasios MandroukasAthanasios Mandroukas
Athanasios Mandroukas
GMGeorge Mavrommatis
George Mavrommatis
KCKosmas Christoulas
Kosmas Christoulas
TMThomas Metaxas
Thomas Metaxas

8 June 2023 in Applied Sciences
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Lazaros VardakisLazaros Vardakis
Lazaros Vardakis
Yiannis MichailidisYiannis Michailidis
Yiannis Michailidis
PTPanagiotis Pierre Topalidis
Panagiotis Pierre Topalidis
CZCharalambos Zelenitsas
Charalambos Zelenitsas
Athanasios MandroukasAthanasios Mandroukas
Athanasios Mandroukas
TMThomas Metaxas
Thomas Metaxas
The aim of this study was to apply a training plan to four different-length microcycles (MIC) in soccer and analyze (a) the load within the training weeks and (b) the short-term effect on the matches that were played at the end of each microcycle. An intervention training program applied to microcycles of five, six, seven and nine days during two seasons of the Cypriot Fist Division. The GPS technology and subjective (wellness, RPE) assessments were used to monitor the load throughout trainings and games. In weekly external load, there were differences between the four microcycles, with a lower load in MIC5 for all the parameters and higher on MIC9 in the most of them (p < 0.05). In RPE, MIC9 (229 ± 60 arbitrary units (au)) differed significantly from MIC5 (229 ± 60 au, p < 0.001), MIC6 (281 ± 67 au; p < 0.001) and MIC7 (297 ± 48 au, p = 0.009). MIC5 also differed from MIC6 (p = 0.001) and MIC7 (p < 0.001). In the game external load, the only differences found in GDEC2 (game decelerations) were between MIC7 (68 ± 10 number (n)), MIC5 (61 ± 11 n, p = 0.035) and MIC6 (60 ± 10 n, p = 0.002); in GSPEF (game speed efforts), between MIC5 (40 ± 17 n), MIC7 (48 ± 14 n, p = 0.004) and MIC9 (48 ± 16 n, p < 0.001) and between MIC6 (41 ± 14 n), MIC7 (p = 0.009), and MIC9 (p = 0.009); in GMPW5 (game metabolic power efforts), between MIC7 (1307 ± 271 n), MIC5 (1201 ± 340 n, p = 0.035) and MIC6 (1178 ± 261 n, p = 0.001). No differences were found for wellness and perceived exertion. It is important for performance coaches to adapt the training load to the length of the microcycle, applying a lower load to short training weeks and manage the load fluctuation on long training weeks in terms of volume, intensity and recovery. In our study, the results confirmed that this strategy could result in similar performance in the games, regardless of microcycle length.

5 March 2025 in Applied Sciences
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Journal Article
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Yiannis MichailidisYiannis Michailidis
Yiannis Michailidis
Andreas StafylidisAndreas Stafylidis
Andreas Stafylidis
Athanasios MandroukasAthanasios Mandroukas
Athanasios Mandroukas
ANGELOS E. KYRANOUDISANGELOS E. KYRANOUDIS
ANGELOS E. KYRANOUDIS
GAGeorgios Antoniou
Georgios Antoniou
TMThomas Metaxas
Thomas Metaxas
Football is a sport in which athletes perform many movements using one of their legs, which is characterized as dominant. This differentiation in usage often creates asymmetries between the limbs, which has been noted to be related to the occurrence of injuries as well as negative effects on performance. To assess these asymmetries, vertical jump tests, as well as tests using an isokinetic dynamometer, were employed. The aim of this study was to examine the relationship between the asymmetries observed in the application of the single-leg countermovement jump (SLCMJ) and those observed through isokinetic strength assessment at 60°/s, 180°/s, and 300°/s in high-level youth football players. The study involved 63 elite youth football players. For statistical analysis, correlation analysis and linear regression analysis were used. The results showed a significant positive correlation between the CMJ Bilateral Asymmetry Index and the BAI Anterior Quadriceps (60°/s) (r = 0.262, p = 0.038, 95% CI [0.016, 0.479]), indicating a small-to-moderate effect size (Fisher’s z = 0.269, SE = 0.129). Additionally, a significant negative correlation was identified between the CMJ Bilateral Asymmetry Index and the BAI Posterior Hamstrings (60°/s) (r = −0.319, p = 0.011, 95% CI [−0.525, −0.077]), demonstrating a moderate inverse relationship (Fisher’s z = −0.331, SE = 0.129). The overall regression model was significant, F(6,56) = 2.42, p = 0.038, R2 = 0.206, indicating that the predictors collectively explained approximately 20.6% of the variance in the CMJ Bilateral Asymmetry Index. From the findings of this study, we conclude that the SLCMJ asymmetry index cannot replace the asymmetry index from isokinetic strength tests.

17 February 2023 in Applied Sciences
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Journal Article
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MCMichalis Christaras
Michalis Christaras
Yiannis MichailidisYiannis Michailidis
Yiannis Michailidis
Athanasios MandroukasAthanasios Mandroukas
Athanasios Mandroukas
Lazaros VardakisLazaros Vardakis
Lazaros Vardakis
KCKosmas Christoulas
Kosmas Christoulas
TMThomas Metaxas
Thomas Metaxas
The aim of the study was to investigate the effect of a half-time short re-warm-up (RW) strategy on the performance of young soccer players in tests of physical abilities and running performance during matches. Twenty-three players (under 17) participated in the study. Body temperature, 10 m sprint, 30 m sprint, the Illinois agility test, countermovement jump (CMJ), and squat jump (SJ) were measured, immediately post-warm-up. Then in one condition, the tests were repeated after a passive rest, and in the other condition, after a 12 min passive rest and 3 min RW. Furthermore, the RW was applied at half-time of two of the four matches where the running performance was measured in the first quarter of the two halves. The results showed that the two conditions differed significantly in the 10 m sprint and CMJ performances (p < 0.001 and p = 0.049, respectively). After the passive rest, a significant decrease in body temperature and performance in SJ was observed (p < 0.001 for both). No other differences were observed. In conclusion, the short RW program can limit the decrement in performance in power tests such as sprints and jumps.

4 April 2025 in Applied Sciences
Verified
Journal Article
Open access
PDF file
Yiannis MichailidisYiannis Michailidis
Yiannis Michailidis
Andreas StafylidisAndreas Stafylidis
Andreas Stafylidis
Lazaros VardakisLazaros Vardakis
Lazaros Vardakis
ANGELOS E. KYRANOUDISANGELOS E. KYRANOUDIS
ANGELOS E. KYRANOUDIS
VMVasilios Mittas
Vasilios Mittas
TMThomas Metaxas
Thomas Metaxas
The running performance of football players is influenced by their team’s formation as well as by their playing position. The creation of the external load profile provides information to the coaching staff for personalized loading of the players based on their playing positions. The aim of this study was to create the athletic running profile of high-level football players under 17 years of age (U17) in the 1-4-3-3 formation, and to investigate the differences between the playing positions in the formation. The study involved 20 football players from a football academy of a professional team. For the study, 13 league matches were used in which the team played with the 1-4-3-3 formation. Positions were classified as central defenders (CDs), side defenders (SDs), central midfielders (CMs), side midfielders (SMs), and forwards (Fs). The players’ movement patterns were captured using a GPS device and categorized into six velocity zones (first: 0.1–7.19 km/h, second: 7.2–10.99, third: 11–14.39 km/h, fourth: 14.4–19.79 km/h, fifth: 19.8–25.19 km/h, sixth: >25.2 km/h). The accelerations and decelerations recorded were those exceeding 2 m/s−1. The level of statistical significance was set at p < 0.05. The results showed that CMs exhibited the greatest external load in total distance and in specific distances in the other velocity zones (p < 0.05). Forwards dominated high-intensity efforts, leading in Distance Zone 5 with SD (mean = 555 m and mean = 559 m, respectively), as well as in Distance Zone 6 (F: mean = 146 m) and in high-speed running values (mean = 701 m). Side players, particularly SD and SM, contributed dynamically through elevated high-speed running (p < 0.05) and maximum speed (p < 0.05), reflecting their role in both transitions and positional phases of play. The study’s results clearly show that the physical demands of the playing positions in the 1-4-3-3 formation differ. This difference is likely due to the different tactical roles of each playing position. This variation between playing positions emphasizes the need for individualized loading of players during the training microcycle.