| Skeletal muscle accounts for about 40%of the body weight.In addition to exercise function,recent studies have confirmed its powerful metabolic and endocrine functions.It has become a relatively basic research to influence skeletal muscle through exercise training and then play its function.As a practical and applied guiding research,how and when exercise can better affect skeletal muscle is worthy of further study.As a researcher of sports human science,it is also very meaningful to explore"how"and"when"with new methods and new theories.Therefore,this study has designed three parts.The first part is to explore which form of exercise has greater impact on the skeletal muscle of mice.The second part is to explore the difference of the effects of early and late day exercise on the skeletal muscle of mice through the theory of biological rhythm.The third part is to carry out the practical verification of human strength training on the basis of the conclusions of the first two animal experiments.Aerobic exercise,resistance training and combined exercise are commonly used in mouse sports training.In recent years,many studies focus on combined exercise and think it can have a better effect.However,there are few means and devices of combined exercise in mice.To solve this problem,in the first part of this study,we designed a new exercise model that can combine aerobic exercise and resistance training,and obtained a patent.Then we compared this method with the treadmill exercise based on 70%VO2max and the ladder exercise based on the maximum load percentage,in order to explore the better exercise method that exercise affects skeletal muscle,this paper discusses how to exercise.Biological rhythms not only exist in the center of the body,but also are active in many peripheral organs.The self-regulation of classical rhythm factors such as per,cry,clock and BMAL1 constitutes the molecular clock basis of skeletal muscle,and rhythm genes have also been proved to be closely related to skeletal muscle.It has become a new scientific problem whether we can choose a better time period for exercise training according to the biological rhythm of skeletal muscle,so as to achieve better training effect.Although some reports reveal that exercise time points should be selected,and it is believed that the biological rhythm fluctuation of hormones,body temperature and other factors plays an important role,but in the peripheral blood,there is no significant difference,however,the role of rhythm factors in it is less involved.Based on this problem,this study explored the rhythm fluctuation relationship between rhythm factor and myogenic factor from C2C12cells and C57 Mouse skeletal muscle,determined the experimental design of resistance training on mice in the morning and afternoon,in order to explore the better exercise time affecting skeletal muscle,and tried to explore the problem of"when to exercise"after re verifying the characteristics of climbing ladder movement.The active and rest patterns of mice are just the opposite of that of humans.It has been reported that athletes have better exercise ability in the afternoon or evening,and after training in the evening,their exercise ability improves more.However,most of these studies are limited to the study of phenotype and lack of direct mechanism.On the basis of the first two parts of this paper,we tested the hypotheses of this paper through strength training of ordinary young men in the morning and afternoon,and analyzed the potential molecular mechanism through a variety of means.Objective:This paper introduces and compares the effects of three different ways of exercise（running based on 70%VO2max,pyramid ladder training based on maximum load and cage climbing by means of self climbing）on skeletal muscle,and selects a better form of exercise for time selection;To explore the rhythm of C2C12 cells,the 24-hour biological rhythm of mouse skeletal muscle,the difference of the effects of climbing exercise on mouse skeletal muscle in the morning and afternoon,and the effects of climbing exercise on mouse lactic acid and myogenic factors,so as to determine the appropriate time for strength training to have a positive impact on skeletal muscle;Objective to explore the influence of strength training in morning and afternoon on body composition,strength and metabolism of ordinary young men,and analyze the better time and potential value of strength training.In order to provide theoretical and practical reference for the choice of sports mode and time point in the field of sports science.Methods:1.The effect of different exercise on skeletal muscle of mice and its mechanismTwenty four 8-week-old male C57 mice were randomly divided into three groups:running,climbing stairs and self climbing.They exercised on Monday,Wednesday and Friday for 8 weeks.The body phenotype,glucose tolerance,muscle and fat mass,muscle morphology and structure,and satellite cell activation were recorded and analyzed.The transcription levels of myogenic gene,protein synthesis gene,protein degradation gene,muscle fiber type gene,mitochondrial function related gene and energy metabolism related gene were determined by RT-PCR.The protein expression levels of the above representative genes were detected by Western blot,Serum metabonomics was used to analyze the differences of metabolites and enrichment pathways after three kinds of exercise,and the relationship between different metabolites and strength and glucose tolerance of mice was analyzed.2.The effect of time selective resistance training on skeletal muscle of mice and its possible mechanism1)Relationship between myogenic factors and rhythm factors in C2C12 cellsThe skeletal muscle cell line C2C12 was used as the research object.After the rhythm was induced by 50%horse serum,the expression of 8 hours,12 hours,16hours,20 hours,24 hours and 28 hours rhythm genes and myogenic genes were determined;RT-PCR was used to analyze the expression of rhythm gene and myogenic gene on the first day,the second day,the third day and the fourth day;The plasmids with Bmal1 as transcription factor and myogenic factor Myo D as promoter were constructed and transfected into 293T cells.2)Study on the rhythm of muscle factor expression in skeletal muscle of miceEighteen 8-week-old C57 male mice were randomly divided into 6 groups.The samples were collected at 9:00,13:00,17:00,21:00,1:00 and 5:00 respectively.The samples were collected about 10 minutes at each time point.ELISA was used to detect serum indexes.RT-PCR was used to detect the levels of rhythm factors Per1,Per2,Cry1,Cry2,CLOCK,Bmal1 and Myo D at different time points.3)Effects of resistance training in the morning and afternoon on skeletal muscle of mice and its possible mechanismTwenty two 8-week-old C57 male mice were randomly divided into control group,morning exercise group（E9,training at 8am）and afternoon exercise group（E17,training at 4pm）.They exercised every Monday,Wednesday and Friday for 10weeks,and the data were collected at noon every Sunday.The body weight,body fat ratio,GTT,ITT,grip strength,muscle wet weight and cross-sectional area of muscle fiber were recorded.The expression levels of muscle fiber type gene,myogenesis,differentiation,secretion and fusion gene and neuromuscular junction gene were detected by RT-PCR.The levels of ATP,lactic acid and irisin in gastrocnemius muscle were detected by ELISA.Western blot was used to detect the expression level of Pax7,Myo D protein and phosphorylation of m TOR and P70S6K.4)Effects of one-time resistance training on anaerobic metabolism of skeletal muscle in miceThirty three 8-week-old C57 male mice were used as the experimental objects.After the training was adapted and the maximum load was determined,the serum and skeletal muscle lactate levels were detected by ELISA before the beginning of resistance training,50%max,75%max,100%max,75%max,50%max,5 min,15min,30 min,60 min and 120 min after exercise,RT-PCR was used to detect the transcription levels of myogenic genes Myo D,myogenin and mitochondrial genes Mfn1,Mfn2 before and immediately after exercise.3.The influence of strength training in the morning and afternoon on body composition,strength and metabolism of young menTwenty four male college students aged 18-25 were recruited and divided into two groups according to the ratio of maximum strength to muscle mass（no statistical difference）.They were given strength training in the morning and afternoon,with12rm as the load.They were given left and right leg flexion and extension training and sitting position pull-down training every time.They were trained every Monday,Wednesday and Friday for 4 weeks.Data were collected at noon every Sunday,After8 weeks of recovery,the data and blood samples were collected again.The serum and plasma indexes were detected by ELISA.The differences of serum metabolites were detected by metabonomics.The types of different metabolites and enrichment pathways were analyzed.Results:1.The effect of different ways of exercise on skeletal muscle of mice and its possible mechanismThe results showed that the weight gain of mice decreased,white fat decreased,muscle fiber structure had a benign adaptation,blood glucose tolerance increased,and satellite cells activated;In terms of inhibiting weight gain,the effect of self climbing is better.In terms of muscle hypertrophy,satellite cell activation and grip strength,the effect of resistance training is better;The results of PCR and protein detection showed that the three kinds of exercise increased the energy metabolism of mice.Resistance training had obvious effects on myogenesis,protein synthesis and inhibition of protein degradation.Aerobic exercise had obvious effects on mitochondrial biogenesis and mitochondrial function;After aerobic exercise,the metabolism of glucose and lipid was mainly concentrated in the differential metabolite accumulation pathway,and the resistance training was mainly concentrated in the amino acid metabolism,while the self climbing exercise had both characteristics;From the physiological phenotype to the molecular phenotype,and then to the metabolic phenotype,we can find the corresponding relationship.There is a correlation between the different metabolites and the power and glucose tolerance,and the power is stronger.2.The effect of time selective resistance training on skeletal muscle of mice and its possible mechanism1)After C2C12 cells were stimulated with 50%horse serum,Bmal1 gene and Myo D gene fluctuated within 24 hours;C2C12 cells could differentiate in 4 days.During the differentiation,myogenic factor Myo D expression and rhythm gene Bmal1 expression increased;It was found that Bmal1 could bind to Myo D promoter and activate the transcription of Myo D promoter.2)There was a fluctuation of rhythmic factor gene m RNA expression in skeletal muscle of mice during 24-hour cycle,which existed in both fast and slow muscles;in gastrocnemius,the rhythmic fluctuation of clock,Bmal1,irisin and Myo D m RNA levels was similar,higher in the morning and lower in the afternoon.3)Resistance training in the morning and afternoon had positive effects on grip strength,skeletal muscle hypertrophy and glucose metabolism;However,the effect of morning training group was better,which showed more muscle fibers with larger cross-sectional area and greater muscle quality;The morning training group showed better performance in inhibiting protein degradation,promoting myogenesis,differentiation and fusion;There was no significant difference in neuromuscular junction,ATP,lactic acid and satellite cell activation between the morning and afternoon exercise groups.The morning exercise group showed better performance in irisin level,myogenesis and protein synthesis of gastrocnemius muscle.4)One time resistance training can improve the level of lactic acid in gastrocnemius muscle and serum of mice.The peak of lactic acid in gastrocnemius muscle appears after the maximum load exercise,and the peak of lactic acid in serum appears 5 minutes after the exercise.Immediately after one-time exercise,the m RNA levels of myogenic genes Myo D and myogenin in gastrocnemius muscle increase,but the m RNA levels of mitochondrial related genes change little.3.The influence of strength training in the morning and afternoon on body composition,strength and metabolism of young menCompared with the end of the recovery period after exercise,exercise in the morning and afternoon can reduce the body fat content of young men and increase muscle strength;the results showed that the levels of TG,TC,NEFA and LDL in serum were decreased,and the levels of HDL and irisin in serum were increased.The effect was stronger in the afternoon training group.The difference of serum metabolites was more obvious in the afternoon training group.The difference of metabolites was mainly concentrated in amino acid metabolism and vitamin metabolism.Conclusions:1.The three forms of exercise had a positive effect on skeletal muscle,which was corresponding to the metabolic phenotype of serum1)All three forms of exercise can inhibit weight gain,increase sugar tolerance level and increase energy metabolism.2)The cage climbing movement is a kind of comprehensive sport form which is worth recommending because it has the characteristics of resistance training and aerobic movement.3)The resistance training can improve the muscle function,increase muscle strength and regulate metabolism stability by promoting muscle formation and improving skeletal muscle function.4)The metabolites and their enrichment pathways can be regarded as functions or markers of different modes of movement.2.Compared with afternoon,the morning exercise induced muscle formation and improved skeletal muscle function due to the strong regulation of rhythm factors1)Myo D gene promoter of C2C12 cells is regulated by rhythm gene Bmal1.2)The expression of myogenic factor and rhythmic factor was higher in the morning（am 8-9o’clock）and lower in PM 4-5 o’clock in the afternoon.3)The anti resistance training had a positive effect on the strength and sugar metabolism of mice last afternoon.The effect of the morning training group was more significant,which might be that the resistance training activated satellite cells,and Myo D,the rhythmic expression of Myo D,made the effect of training and rhythm superimposed,thus the training effect of the last afternoon was different.4)One time of resistance training can improve the level of lactate in gastrocnemius and serum of mice,and the expression of Myo D and myogenin genes increased.3.Compared with the morning,strength training in the afternoon has better effect on the strength,body composition and serum metabolite of young men1)The physical composition,strength and metabolism level of young men were improved by strength training last afternoon,and the effect of afternoon was better.2)Strength training mainly affects the amino acid metabolism pathway and vitamin metabolism pathway. |
PDF Full Text Request