Akutni učinki kofeina na utrujenost v normobarični hipoksiji : magistrsko delo

Štritof, Ana (author), Debevec, Tadej (mentor), Rauter, Samo (comentor)

V magistrski nalogi smo preučevali potencialne učinke kofeina med kolesarjenjem na cikloergometru na simulirani višini 3500 m (normobarična hipoksija; O2 = 13,5 %) z namenom ugotoviti morebiten pozitiven učinek kofeina na športno sposobnost v hipoksiji. Obenem smo preučevali tudi vprašanje, ali je učinek kofeina drugačen pri moških kot pri ženskah in morebitne ostale razlike med spoloma. V raziskavo je bilo vključenih 26 zdravih odraslih udeležencev (13 moških, 13 žensk). V glavnem delu raziskave je bila izvedena randomizirana navzkrižna študija štirih vadbenih testiranj oz. eksperimentalnih pogojev; normoksija (normalno okolje) v primerjavi s hipoksijo (delež vdihanega kisika = 13,5 %) in placebo (20 g maltodekstrina) v primerjavi s kofeinom (20 g maltodekstrina + 6 mg/kg telesne mase kofeina). Vsako testiranje je vključevalo meritve med submaksimalnim naporom v obliki 10-minutnega kolesarjenja na 40 % VO2max, za tem pa je sledil stopnjevani obremenitveni test. V času vseh testiranj so bile merjene naslednje spremenljivke: privzem kisika (VO2), ventilacija, frekvenca srca, saturacija (SpO2), koncentracija laktata, ocena napora in maksimalna sposobnost. Pri submaksimalnem naporu v normobarični hipoksiji so nastale statistično značilne razlike ob dodajanju kofeina pri saturaciji kisika krvi (81 ± 5,6 % vs. 78 ± 5,5), oceni napora (12 vs.13) in koncentraciji laktata (4,4 ± 1,1 mmol/l vs. 3,7 ± 1 mmol/l). Pri maksimalnem naporu se je učinek kofeina kazal v višji maksimalni doseženi moči (277 ± 56W vs. 267 ± 55W), privzemu kisika (48 ± 8,9 ml/kg/min vs. 44 ± 9,1 ml/kg/min), maksimalni frekvenci srca (182 ± 12 utripov/min vs. 179 ± 9 utripov/min) in koncentraciji laktata (10,9 ± 2,8 mmol/l vs. 9,6 ± 2,6 mmol/l). Na podlagi rezultatov smo ugotovili, da kofein v pogojih hipoksije izboljša določene vidike športne zmogljivosti, zlasti pri naporih do odpovedi, medtem ko je njegov vpliv na posamezne fiziološke spremenljivke med submaksimalno vadbo manj izrazit. Prav tako se je izkazalo, da kofein vpliva na zaznavanje intenzivnosti napora. Statistično značilnih razlik v odzivu na kofein med spoloma nismo zaznali.

• Language: Slovenian
• Keywords: hipoksija, kofein, razlike med spoloma, cikloergometer
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FŠ - Faculty of Sport
• Year: 2025
• PID: 20.500.12556/RUL-170665
• COBISS.SI-ID: 250074115
• Publication date in RUL: 12.07.2025

Secondary language

• Language: English
• Title: Acute effects of caffeine on fatigue in normobaric hypoxia

Abstract

The present master thesis aimed to examine the effect of caffeine during cycling on a cycle ergometer at a simulated altitude of 3500 m with the key aim to measure and determine the effect of caffeine in hypoxia on athletic performance. We also wanted to investigate whether the effect of caffeine differs between men and women and in other gender-related differences. For this purpose, 26 healthy adult participants (13 men, 13 women) iwere recruited for the present study. The main part of the project was conducted as a randomized crossover study with four experimental conditions: normoxia (ambient air) versus hypoxia (inspired oxygen fraction = 0.135), and placebo (20 g maltodextrin) versus caffeine (20 g maltodextrin + 6 mg/kg body weight caffeine). Each trial included a submaximal exercise test consisting of 10 minutes of cycling at 40% VO₂max, followed by an incremental test to exhaustion. The continuously measured variables included oxygen uptake (VO₂), ventilation, heart rate, oxygen saturation (SpO₂), lactate concentration, rating of perceived exertion, and maximal power output. During submaximal exercise in normobaric hypoxia, statistically significant differences were observed with caffeine ingestion in blood oxygen saturation (81 ± 5.6% vs. 78 ± 5.5%), perceived exertion (12 vs. 13), and blood lactate concentration (4.4 ± 1.1 mmol/L vs. 3.7 ± 1.0 mmol/L). Under maximal effort, the effect of caffeine was reflected in a higher peak power output (277 ± 56 W vs. 267 ± 55 W), oxygen uptake (48 ± 8.9 ml/kg/min vs. 44 ± 9.1 ml/kg/min), maximal heart rate (182 ± 12 bpm vs. 179 ± 9 bpm), and blood lactate concentration (10.9 ± 2.8 mmol/L vs. 9.6 ± 2.6 mmol/L). Based on the results, we concluded that caffeine enhances certain aspects of athletic performance in hypoxia, particularly at maximal effort, whereas its effect on some physiological variables during submaximal exercise is less pronounced or inconsistent. It was also found to influence the perception of exertion. However, no significant differences were observed between men and women in their response to caffeine.

• Keywords: hypoxia, caffeine, sex differences, cycle ergometer