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Effects Of Different Doses Of Caffeine Intake On Endurance Quality Of Firemen In High Temperature And Humidity Environment

Posted on:2024-07-31Degree:MasterType:Thesis
Country:ChinaCandidate:X N ZhangFull Text:PDF
GTID:2557307178454284Subject:Human Movement Science
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Purpose: The movement and working ability of human body are greatly affected by external environment and nutritional factors.Caffeine has been widely shown to enhance athletic performance.Firefighters are inevitably working in high temperature and humidity.To reduce the risk of working in special environments,a supplement is needed to enhance athletic performance.Therefore,the purpose of this study was to explore whether caffeine has an energizing effect on the exercise performance of firefighters under high temperature and humidity environment,and whether the effects of different doses are different.Methods: Recruit 12 firefighters from the Yatai Detachment of Changchun City,Jilin Province to complete the experiment.Double-blind,randomized crossover experimental design was used.This experiment includes one pre-experiment and four formal experiments.In the formal experiment,after arriving at the site and sitting for 30 minutes under normal temperature,the firefighters measured heart rate(HR),blood pressure(BP),visual simple reaction time(RT),blood lactic acid(BLA),sublingual temperature(OT),and then took different doses of caffeine by oral capsule,namely,placebo group(CON group,0mg/kg),low-dose caffeine group(CAF3 group,3mg/kg)Medium-dose caffeine group(CAF6 group,6mg/kg)and high-dose caffeine group(CAF9 group,9mg/kg)sat for30 minutes,and then tested the HR,BLA,BP,OT and RT values after ingestion.After the test,warm up for 10 min and rest for 10min;After 60 minutes of caffeine intake,adjust the powered bicycle,and conduct the powered bicycle exhaustion test in a high temperature and humidity environment warehouse(40 ℃,100% rh).During this period,ask and record the subjective force perception scale(RPE)every 2 minutes,pay real-time attention to the changes of subjects’ HR,record the exhaustion time(TTE),maximum load(PL),and collect the HR,BLA,BP,OT,and RT values for the third time.The experimental results were analyzed using SPSS 24.0(IBM,Armonk,NY,USA),and all test data were expressed as mean ± standard deviation.The significance level was set as p<0.05..Results:1.Exercise performance: Compared with CON group,TTE of CAF3 group and CAF6 group was significantly increased(p<0.001,p<0.001).At the same time,compared with CAF9 group,the exhaustion time of CAF3 group and CAF6 group was significantly increased(p<0.05,p<0.05).In the aspect of PL,the difference between CON group,CAF3 group,CAF6 group and CAF9 group was statistically significant(p<0.001).Compared with CON group,the maximum load of CAF3 group and CAF6 group was significantly increased(p<0.001,p<0.001).At the same time,compared with CAF9 group,the maximum load of CAF3 group and CAF6 group was significantly increased(p<0.001,p<0.01).2.HR&BP: In HR,there was a significant interaction between intake dose and time(p<0.05).After exercise,the heart rate of CON group was significantly lower than that of CAF3 group,CAF6 group and CAF9 group(p<0.05).In terms of systolic blood pressure,there was a significant interaction between intake dose and time(p<0.05).After exercise,compared with before and after ingestion,systolic blood pressure in CAF3,CAF6 and CAF9 groups increased significantly with the increase of exercise time(p<0.001).After exercise,the systolic blood pressure of CON group was significantly lower than that of CAF3 group,CAF6 group and CAF9 group(p<0.05).In terms of diastolic blood pressure,there was no significant interaction between intake dose and time(p>0.05),but there was significant statistical difference in time(p<0.01).3.RT: The interaction of intake dose and time had a statistically significant effect on reaction time(p<0.05).After 30 minutes of ingestion,the reaction time of CON group was significantly higher than that of CAF3 group,CAF6 group and CAF9 group(p<0.05),and the reaction time of CAF3 group was significantly lower than that of CAF9 group(p<0.05).After exercise,the reaction time of CON group was significantly higher than that of CAF3 group,CAF6 and CAF9 group(p<0.001,p<0.001),and the reaction time of CAF9 group was significantly higher than that of CAF3 group(p=0.002)and CAF6 group(p=0.038).After 30 minutes of caffeine intake,the reaction time of CAF3 and CAF6 groups was significantly lower than that before caffeine intake.After exhaustion,the reaction time of each group was significantly lower than that before and 30 minutes after caffeine intake.4.BLA: The interaction of intake dose and time had a statistically significant effect on blood lactate concentration(p<0.05).Compared with before and after ingestion,the blood lactic acid concentration of each group was significantly increased after exercise.At the same time,after exercise,the blood lactic acid concentration in CAF3 group was significantly higher than that in CON group(p<0.05),and the blood lactic acid concentration in CAF6 group was significantly higher than that in CON group(p<0.05).5.OT: There was no significant interaction between intake dose and time(p>0.05),but there was significant statistical difference in time(p<0.001).During the whole exercise process,sublingual body temperature increases with the extension of exercise time,but different caffeine intake doses have no statistical difference on sublingual body temperature6.The interaction of intake dose and time had a statistically significant impact on the average RPE(p<0.05).During exercise,the average RPE of each group increased significantly with the increase of exercise time.After 4 minutes of exercise,the average RPE of CON group was significantly higher than that of CAF6 group(p<0.05).After 6 minutes of exercise,the average RPE of CON group was significantly higher than that of CAF6 group(p<0.05).After 8minutes of exercise,the average RPE of CON group was significantly higher than that of CAF3 group and CAF6 group(p<0.001),and that of CAF9 group was significantly higher than that of CAF3 group and CAF6 group(p<0.001).Conclusions: In this study,it was found that compared with placebo,different doses of caffeine can improve the performance of firefighters in high temperature and high humidity environment;Compared with high dose of caffeine,low and medium dose of caffeine can improve the endurance exercise ability of firefighters in high temperature and high humidity environment.However,the increase of caffeine intake from low dose(3mg/kg)to medium dose(6mg/kg)will not provide additional synergism.
Keywords/Search Tags:Caffeine, High temperature, High humidity, Fireman, Athletic performance Constructivism
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