| Objective:With the development of national sports and the goal of strengthening the army,highintensity sports and training activities are increasing day by day.High-intensity exercise,especially centrifugal exercise,is easy to cause skeletal muscle injury.Some studies have shown that the incidence of skeletal muscle injury is 10%?55%.The clinical manifestations are mainly delayed local muscle swelling,pain and limb movement limitation.Moreover,the process of muscle regeneration is slow and easy to form scar tissue,which results in the hindrance of muscle rehabilitation and increases the probability of secondary injury.Sports and life have serious consequences.Therefore,how to accurately evaluate the severity of skeletal muscle injury and intervene early and effectively to reduce the probability of secondary injury has always been the focus of sports medicine research.In this study,we intend to establish different degrees of acute skeletal muscle injury models by using animal exercise platform at different time.The target muscle samples were taken to observe the injury at a given time period after different exercise loads under light microscopy.The changes of serum creatine kinase isoenzyme(CK-mm)level and tumor necrosis factor-alpha(TNF-alpha)and interleukin in rats after exercise were detected.The expression of inflammatory factors such as 1beta(IL-1beta)and interleukin-6(IL-6)was used as biochemical evidence to verify muscle injury.At the same time,the projection temperature of target muscle surface was monitored by infrared thermal imaging technology at a given time point after exercise,and the relationship between the three factors was analyzed according to the data obtained.The purpose of this study is to verify the effectiveness and sensitivity of infrared thermal imaging as a non-invasive and simple method in monitoring and judging muscular motor injury.Methods:(1)Establishment of experimental grouping and skeletal muscle injury model: 100 10-week-old male Wistar rats were randomly divided into five groups: control group(KB group),30-minute exercise group(A group),60-minute exercise group(B group),90-minute exercise group(C group)and 120-minute exercise group(D group),with 20 rats in each group.The control group did not apply exercise load,while the exercise group continued to exercise at a speed of 16 meters per minute on a small animal platform with a slope of-16 degrees for different periods of time.(2)Infrared thermal imaging of target muscle was monitored at 6 time points(before exercise,immediately after exercise,8 hours,16 hours,24 hours and 3 days after exercise).Triceps brachii muscle,which was the most easily injured muscle during centrifugal downhill running,was selected as the target muscle.Infrared thermal imaging data of target muscle surface were monitored and recorded at 6 time points in group A?D.In KB group,the data were recorded at the same time point as the normal physiological fluctuation of temperature.(3)Detect the different degree of skeletal muscle injury: At 5 time points(immediately after exercise,8 hours after exercise,16 hours,24 hours and 3 days after exercise),4 rats in group A?D were randomly selected and executed for cervical dislocation(4 rats in group KB were also randomly executed at the same time).About 1.0 mm x 1.0 mm x 0.2 mm muscle mass was taken from the lower end of the medial head of triceps brachii muscle of right forelimb at the junction of muscles and abdomen.Routine paraffin embedding and HE staining.2.Two HE sections were made in each rat,and the histological changes of skeletal muscle were observed under light microscope.Each specimen was observed and counted twice by two researchers at different times.(4)To detect the changes of biochemical indexes in rats at different time points: at the same time,the abdominal aorta blood was taken from the muscle samples of the rats,and the levels of tumor necrosis factor-alpha(TNF-alpha),interleukin-1bet(IL-1bet),interleukin-6(IL-6)and creatine kinase isoenzyme(CK-mm)in the serum were detected.5.Perform statistical analysis based on the data obtained and summarize the results.Results:(1)There was no statistical difference between KB?D group and pre-exercise monitoring data;there was significant difference between A?D group and pre-exercise monitoring data,but there was no statistical significance between each group;there was significant difference between D group and pre-exercise and other groups at 8 hours after exercise,and there was no significant difference between KB?C group and post-exercise monitoring data;there was no significant difference between C and D group and the same group at 16 hours after exercise.There was no significant difference between group C and D before exercise,group A and group B.There was significant difference between group C and group D 24 hours after exercise and before exercise and other groups.There was no significant difference between group C and group D.There was no significant difference between groups 3 days after exercise.(2)There was no significant difference between KB group and A group in the observation of specimens at each time interval.The structure of muscle cells was intact,arranged neatly in honeycomb shape,and no inflammatory cell infiltration was observed.There was only a small amount of muscle cells swelling in group B immediately after exercise,and no obvious abnormality in other time intervals.In group C,muscle cells swelling increased immediately after exercise,interstitial blood vessels dilated,and 16 after exercise.A small amount of inflammatory cell infiltration could be seen in the hourly samples,and the swelling range of myocytes was enlarged 24 hours after exercise,thrombosis was found in some interstitial blood vessels,and inflammatory cell infiltration increased earlier.In group D,most myocytes were swollen immediately after exercise,the original honeycomb structure was blurred,interstitial blood vessels were mostly dilated,and a small amount of inflammatory cell infiltration and transportation could be seen in the 8 hours after exercise.Inflammatory cell infiltration was observed in 16 and 24 hours after operation.Three days after exercise,the specimens of each group were almost the same.(3)The level of serum creatine kinase in group A was similar to that in group KB at each time point,but there was no statistical difference;the value in group B was slightly higher than that in group KB immediately after exercise,but the difference was not significant;the level of creatine kinase in other time points was similar to that in group KB,and there was no statistical difference;the level of creatine kinase in group C and D was statistically different from that in group KB at each time point,among which 24 hours after exercise.Hours showed significant difference,but there was no significant difference between C and D groups.The levels of TNF-a in serum of group A?D could not be detected at all detection points;the levels of IL-6 in serum of group A and B could not be detected at all detection points;the levels of IL-6 in group C and D increased immediately after exercise,with significant difference compared with the control group,and there was no significant difference at other time points compared with the control group;the levels of IL-1beta in serum of group A and B could not be detected at all detection points,and the expression of IL-1beta in group C and D immediately after exercise was not detected.The level of IL-1beta expression in C and D groups reached their peak at 16 hours after exercise,which was significantly different from that in control group.The level of IL-1beta expression decreased from 24 hours to 3 days after exercise,but it was still higher than that in control group.Conclusion:The skeletal muscles of rats are easily damaged during centrifugal exercise,especially during exhaustive centrifugal exercise,and show delayed histological features.90 minutes exercise load is the critical point of skeletal muscle injury.120 minutes exhaustive exercise can maximize skeletal muscle injury.The serum CK level in the biochemical test after exercise can be used to judge the injury,and the expression of inflammatory factors is more representative of IL-1beta.Infrared thermal imaging technology can detect the change of projection temperature of target muscle after exercise,and its sensitivity is not lower than serum CK test in the case of skeletal muscle injury.Therefore,infrared thermal imaging technology as a non-invasive,simple means of detection in the diagnosis and monitoring of skeletal muscle injury is worth promoting. |
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