| Objective:Weighted stair climbing exercise is the first type of exercise that firefighters must accomplish in order to execute fire-fighting and rescue activities in high-rise structures.This activity causes a series of complicated and systematic metabolic changes in the organism.Nowadays,most fire-fighting teams examine physical fitness and fire-fighting and rescue capabilities from a macroscopic perspective,such as conventional and single physical fitness test results;the overall physical function of firefighters after training is evaluated by physiological and biochemical indicators,and detailed studies on the metabolite level of firefighters are difficult to conduct.In a non-targeted metabolomic fashion,this study used UPLC-MS to screen for difference metabolites and metabolic pathways in urine samples from volunteers before(group A),immediately after(group B),and 24 hours after(group C)simulated weighted stair climbing exercise.Simulated training combined with heart rate and urine routines,as well as comprehensive metabolite measurements,can be used to help understand the current status of firefighters,and to first investigate the characteristics of changes in body substance and energy metabolism,oxidative stress,immune response,and physical performance during simulated weighted stair climbing training,in order to promote the scientific and modernisation of firefighter training at a local level.Methods:In this study,18 male firefighters from Shanghai Fire Brigade’s Pengpu Squadron were chosen as experimental subjects,and they wore approximately 50 Kg of high-rise firefighting equipment to conduct simulated weighted stair climbing training on a 10-story building with a total floor height of 31 m,while their heart rates were recorded throughout.Three sets of urine samples were taken and regular urine parameters were evaluated.The UPLC-MS technique was used to analyze the pre-treated urine samples,and the raw histology data was pre-processed using XCMS software.The Met DNA2 website provides FC values and paired t-test p-values for metabolites in groups A and B,as well as groups A and C.Metabo Analyst 5.0 was used to perform PCA and PLS-DA,and major differential metabolites were identified when metabolites met p<0.05,VIP > 1 and FC > 1.5 or FC<0.67,as well as pathway and enrichment analyses.Results:(1)The firefighters’ mean heart rate in the calm condition before activity was78.88 ±7.65 bpm,whereas the mean maximum heart rate throughout exercise was182.13 ±11.95 bpm,a significant difference(p=0.01).The findings of a urine routine revealed that some firefighters had an increased amount of positive urine protein immediately following exercise.The weighted stair climb took an average of 88.87 ±14.56 seconds to complete.According to the most recent national fitness test criteria,the mean score for this activity was 98.61,and it was performed in good condition.(2)The UPLC-MS analytical platform discovered substantial changes in the metabolic profiles of urine samples between Groups A and B,as well as between Groups A and C.There were 117 metabolites that were substantially different between Group A and Group B;the screening of Group A and Group C yielded 93 important difference metabolites.(3)The key metabolic pathways that differed between groups A and B were-alanine metabolism,histidine metabolism,alanine,niacin,and nicotinamide metabolism,and tryptophan metabolism.Alanine,aspartate,and glutamate metabolism,histidine metabolism,linoleic acid metabolism,and other metabolic pathways differed between groups A and C.Conclusion:(1)The training is rigorous,and it is common for firefighters to experience exercise fatigue.The training results,in accordance with international authorities and the most recent domestic assessment standards,can better meet the current needs of the national comprehensive emergency rescue team for professional combat.(2)There were significant changes in the levels of the differential metabolites-alanine,carnosine,L-valine,citrate,and hypoxanthine,which are related to substance and energy metabolism;the metabolites L-glutathione and N-acetyl-cysteine,which are related to oxidative stress,were up-regulated in the immediate post-exercise period,while the relative levels of nicotinamide,N1-methylnicotin The immunerelated metabolites kynurenine and kynurenine were increased and downregulated,respectively,in the immediate post-exercise interval.(3)Simulated weight-bearing stair climbing training may have an effect on the amino acid,lipid,oxidative stress,and immune response metabolic pathways in the human body.The significant increase in urinary hypoxanthine and citrate levels immediately following high-intensity training could be used as a direct indicator of exercise fatigue,which could be used to monitor exercise intensity and further improve the overall performance of firefighting squadrons in special training. |
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