Browsing by Author "Hazir, Tahir"

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The Contribution of Energy Systems in Repeated-Sprint Protocols: The Effect of Distance, Rest, and Repetition
(Routledge Journals, Taylor & Francis Ltd, 2023) Ulupinar, Suleyman; Hazir, Tahir; Isler, Ayse Kin
Purpose: This study aims to investigate the effects of rest intervals, sprint distance, and number of repetitions on performance variables, physiological responses, and energy system contributions in repeated-sprint protocols when total distance variable was the controlled (300 m). Method: Sixteen male soccer players participated in this study. The four protocols, each totaling a distance of 300 m, consisted of the combination of 15 and 30 m sprints with 30 s rest intervals (15meters30sec and 30meters30sec, respectively) and 1:5 work-rest ratios (15meters12sec and 30meters22sec, respectively). Aerobic, glycolytic, and phosphagen energy systems' contributions were calculated from the oxygen consumption (VO2) during the exercise, net lactate production, and the recovery VO2 kinetics using mono-exponential models. Repeated measures ANOVA with the Bonferroni correction was applied to examine the hypothesized differences. Results: The findings indicated that total sprint duration (F3:45=281.14; p<0.001), percentage of performance decline (F3:45=16.58; p<0.001), delta lactate (F3:45=39.72, p<0.001), rating of perceived exertion (F3:45=28.64; p<0.001), energy demand (F3:45=101.6; p<0.001), VO2 during the rest intervals (F3:45=42.72; p<0.001), and the absolute contribution of glycolytic (F3:45=119.6; p<0.001) and phosphagen energy systems (F3:45=72.9; p<0.001) were lowest in the 15meters30sec compared to other protocols. However, the relative contribution of aerobic system was greatest in the 15meters30sec compared to other protocols (F3:45=28.1, p<0.001). Both absolute (F3:45=119.6; p<0.001) and relative contribution of glycolytic system (F3:45=88.5, p<0.001) were greatest in the 30meters22sec compared to other protocols. Conclusion: This study showed that increasing sprint distance when rest interval is equal and decreasing rest interval when sprint distance is equal can increase the glycolytic system contribution.
Low-to Correlations Between Repeated Sprint Ability and Aerobic Capacity: A Systematic Review and Meta-Analysis
(Lippincott Williams & Wilkins, 2023) Ulupinar, Sueleyman; Ozbay, Serhat; Gencoglu, Cebrail; Hazir, Tahir
This systematic review and meta-analysis aims to provide meta-analytic estimates of the relationships between repeated sprint ability (RSA) outputs (total sprint time [TST] and fatigue scores) and aerobic capacity indicators (V?O-2max, the covered distance in the endurance shuttle run test [SRTdistance], and the velocity at the anaerobic lactate threshold [ALT(velocity)]). To identify potential studies for inclusion, a search strategy was implemented on MEDLINE (through PubMed) and Web of Science. The correlation coefficients between RSA outputs and aerobic capacity indicators were extracted from the individual studies to reveal a pooled correlation. After the identification of studies providing inclusion criteria, 45 studies consisting of 1,488 accumulated participants were included. Meta-analysis showed the positive moderate relationships between TST and V?O-2max (pooled r = 0.444, p < 0.001), TST and SRTdistance (pooled r = 0.465, p < 0.001), TST and ALT(velocity) (pooled r = 0.527, p < 0.001), RSA fatigue score and V?O-2max (pooled r = 0.449, p < 0.001), and RSA fatigue score and ALT(velocity) (pooled r = 0.460, p < 0.001), which showed a low positive relationship between RSA fatigue score and SRTdistance (pooled r = 0.305, p = 0.029). This study showed pooled correlations between RSA outputs and practical aerobic capacity indicators. However, contrary to popular belief that there were stronger relationships, these relationships were low to moderate.