| Abstract | Trening ponavljanih sprintova (RST, engl. repeated sprint training) jest format visokointenzivnog intervalnog treninga koji se posljednjih godina sve učestalije koristi kao trenažna strategija u poboljšanju snage, brzine, izdržljivosti i sposobnosti ponavljanja sprintova. Programirano tjelesno vježbanje može rezultirati nekontroliranim i prekomjernim stvaranjem reaktivnih kisikovih spojeva (ROS, engl. reactive oxygen species) uzrokujući pomak redoks ravnoteže u smjeru oksidansa, međutim ROS također predstavljaju sekundarne glasnike čije stvaranje ima važnu ulogu u regulaciji stanične signalizacije na nivou skeletnih mišića. Cilj istraživanja bio je utvrditi biokemijski odgovor na RST analizom biljega oksidacijskog/antioksidacijskog statusa, mišićnog oštećenja i imunosnog odgovora te ispitati njihovu međusobnu povezanost.
U istraživanje je uključeno 15 studenata prve godine Kineziološkog fakulteta Sveučilišta u Zagrebu, muškog spola, raspona dobi od 18 do 22 godine. Eksperimentalni program RST sastojao se od 2 do 3 seta, 6 do 10 pravocrtnih ili povratnih sprintova na kratkoj dionici s polascima svakih 25 sekundi, isprepletenih s periodima kratkotrajnog pasivnog odmora od 2 minute. Razine 15-F2t-izoprostana (15-F2t-IsoP) u plazmi i 24-satnoj mokraći, superoksid-dismutaze, glutation-peroksidaze i glutation-reduktaze u eritrocitima, urata, ukupnog bilirubina, albumina, transferina i prolaktina u serumu, slobodnog kortizola i katekolamina u 24-satnoj mokraći; kreatin-kinaze, aspartat-aminotransferaze, laktat-dehidrogenaze i mioglobina u serumu; visokoosjetljivog IL-6 i C-reaktivnog proteina u serumu te kompletne krvne slike, određene su u tri vremenske točke: nakon inicijalnog mjerenja (To), nakon finalnog mjerenja (T1) i mjesec dana nakon finalnog mjerenja (T2).
Rezultati ovog rada pokazali su da je RST izazvao značajno povećanje koncentracije 15-F2t-IsoP u plazmi, dok analizom 24-satne mokraće značajne promjene nisu utvrđene, iako se radilo o umjerenom povećanju. Finalno mjerenje, karakterizirano 60%-tnim povećanjem opterećenja u odnosu na inicijalno, rezultiralo je značajnim smanjenjem aktivnosti glutation-reduktaze i koncentracije albumina, ali ne i ostalih biljega antioksidacijskog statusa. Premda je ustanovljen zamjetan porast aktivnosti kreatin-kinaze, sugerirajući kako je došlo do oštećenja mišića, razlike u aktivnostima ipak nisu bile značajne. Program RST rezultirao je značajnim povećanjem koncentracije IL-6 i gotovo nepromijenjenim koncentracijama C-reaktivnog proteina. Mjesec dana nakon završetka RST, zabilježen je značajan pad koncentracije IL-6, broja leukocita i neutrofilnih granulocita. Povećanje koncentracije 15-F2t-IsoP nije bilo povezano s pokazateljima oštećenja mišića i imunosnog odgovora.
Ovo istraživanje je pokazalo da prateći ispitanike kroz vrijeme u kojem je sukcesivno povećavan volumen treninga povećanjem broja sprintova, nije dokazan proporcionalan porast lipidne peroksidacije kao ni porast biljega oštećenja mišića što upućuje na zaključak da se u ovoj vrsti trenažnog protokola vremenom postiže uspješna adaptacija i zaštita od daljnjih oksidacijskih oštećenja. |
| Abstract (english) | Repeated sprint training (RST) is a form of high-intensity interval training in which short-duration all-out sprints are interspersed with short recovery periods. High anaerobic demand and increasing aerobic contribution throughout a bout, as sprints are done with very little recovery in-between, may increase production of reactive oxygen species (ROS) which may lead to oxidative stress (OS). Besides being responsible for cellular damage, ROS are also important molecules serving as secondary messengers in skeletal muscle signaling cascades. The main aim of this study was to investigate the effects of running RST on alterations in redox homeostasis (ARH) by monitoring 15-F2t-isoprostane (15-F2t-IsoP) concentration, widely regarded as the “gold standard” marker for the assessment of in vivo lipid peroxidation. Additionally, the study investigated whether muscle and inflammatory status serve as the contributing factor in ARH during the training period.
Fifteen male physical education students volunteered to participate in the study. The experimental training program consisted of 2-3 sets of 6-10 straight-line or shuttle 20-meter repeated sprints with departures every 25 seconds and 2-minute inter-set passive recovery. The levels of 15-F2t-IsoP were measured in plasma and 24-hour urine, superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) in erythrocytes; uric acid (UA), total bilirubin, albumin, transferrin and prolactin in serum, free cortisol and catecholamines in 24-hour urine; creatine kinase, aspartate aminotransferase, lactate dehydrogenase and myoglobin in serum; interleukin 6, C-reactive protein as well as complete blood counts were determined at three time points: after an initial training session (To), after the final training session (T1) and one month after the final training session (T2).
The significant changes were observed in repeated measures of plasma 15-F2t-IsoP concentration and GR activity. While the median plasma 15-F2t-IsoP increased by 75%, the median GR decreased by 56%. In 24-hour urine samples, 15-F2t-IsoP levels were 25% greater in post-training, although these increase did not reach statistical significance. Following RST erythrocyte SOD and GPx activities were 11% and 27% lower, although these decreases were nonsignificant. The concentration of extracellular antioxidants, except albumin, remained close to the baseline values throughout the training program. RST program did not affect the marker of muscle damage since there were no significant post-training differences in CK activities. Interleukin-6 was significantly increased, while total leukocyte and neutrophil count also increased although the results were not significant. There were no significant correlations between pre-to-post change in muscle damage and inflammation markers and pre-to-post change in any marker of ARH.
Assuming that significant correlation between training volume and post-training 15-F2t-IsoP levels exist and that greater exercise workload elicits greater OS response, the fact that the increase in urinary 15-F2t-IsoP level was much lower than the increase of total training volume from first to the final week and the increase of exercise workload (60%) suggests that RST may cause attenuation of OS. |
