BACKGROUND:Unaccustomed exercise triggers skeletal muscle damage,but produces a specific training effect that reduces muscle re-injury to reduce pain-muscle memory. OBJECTIVE:Based on the etiology of delayed onset muscle soreness,to review the existence and possible mechanism of skeletal muscle memory in delayed onset muscle soreness and to present new insights into the prevention and treatment of delayed onset muscle soreness. METHODS:The first author searched in PubMed,Embase,Web of Science,CNKI and WanFang databases for relevant literature published from January 1990 to December 2022.The keywords were"DOMS,skeletal muscle memory,exercise skeletal muscle adaptation,repeat turn effect,exercise and autophagy,autophagy and inflammation"in English and Chinese,respectively.A total of 102 articles were finally included for review. RESULTS AND CONCLUSION:The etiology of delayed onset muscle soreness is currently believed to be an acute inflammatory response due to metabolic disorders,mechanical injury and oxidative stress,while exercise-induced skeletal muscle memory can reduce delayed onset muscle soreness and exercise re-injury.When the duration,frequency and intensity of centrifugal training are gradually increased,symptoms of the injury can be minimized or even avoided.Therefore,based on the mechanism of exercise-induced skeletal muscle memory,it is the future research direction to find more effective ways to prevent and alleviate exercise-induced muscle injury.This review aims to(1)clarify the existence of exercise-induced skeletal muscle memory;(2)explore the possible mechanisms of exercise-induced skeletal muscle memory and propose the relationship between this memory and skeletal muscle autophagy;and(3)provide new strategies for the prevention and treatment of delayed onset muscle soreness by improving the level of skeletal muscle autophagy.

Ankle joint cartilage injuries could lead to severe pain and limited joint activity,and early diagnosis of ankle joint cartilage injury is particularly important.3D-MR sequences has good diagnostic efficiency for ankle joint cartilage injuries.The research progresses of 3D-MRI in diagnosing ankle cartilage injuries were reviewed in this article.

Objective To assess the short-term effects of bariatric surgery on body composition. Methods Fifty-seven patients who underwent bariatric surgery were assessed by dual-energy x-ray absorptiometry (DEXA) before surgery, and 1 and 3 months after surgery. The body composition indexes of whole body and different regions were compared. Results The body mass index (BMI) decreased by 10.61％ and 18.51％, and the lean mass (LM) by 13.22％ and 14.35％ at 1 and 3 months after surgery, respectively. The A/G far mass (FM) decreased significantly 3 months after surgery (P ＜ 0.05). The bone mineral density (BMD) of the spine increased, but that of the pelvis decreased at 1 and 3 months after the operation, and a reduction was observed in the BMD of the whole body by 1.23％ and 1.45％, respectively (P ＜ 0.05). Compared to the baseline, the bone mineral content (BMC) of the spine, pelvis, and whole body increased at 1 and 3 months post-surgery, with a statistically significant difference (P ＜ 0.05). The FM of the whole body (9.52％ and 22.77％) and four regions (legs, trunk, android, and gynoid) reduced. A significant loss of FM (P ＜ 0.05) was observed in the android region by 15.80％ and 31.86％ at the two follow-ups. Conclusion Bariatric surgery can effectively reduce the patient's BMI and FM in the short term, and promotes the redistribution of fat; however, it may be accompanied by a reduction in LM, while the BMD and BMC change trend of pelvis and whole body are opposite.

OBJECTIVE: To evaluate orthopedic metal artifact reduction algorithm (O-MAR) in CT orthopedic metal artifact reduction at different tube voltages, identify an appropriate low tube voltage for clinical practice, and investigate its clinical application. MATERIALS AND METHODS: The institutional ethical committee approved all the animal procedures. A stainless-steel plate and four screws were implanted into the femurs of three Japanese white rabbits. Preoperative CT was performed at 120 kVp without O-MAR reconstruction, and postoperative CT was performed at 80–140 kVp with O-MAR. Muscular CT attenuation, artifact index (AI) and signal-to-noise ratio (SNR) were compared between preoperative and postoperative images (unpaired t test), between paired O-MAR and non-O-MAR images (paired Student t test) and among different kVp settings (repeated measures ANOVA). Artifacts' severity, muscular homogeneity, visibility of inter-muscular space and definition of bony structures were subjectively evaluated and compared (Wilcoxon rank-sum test). In the clinical study, 20 patients undertook CT scan at low kVp with O-MAR with informed consent. The diagnostic satisfaction of clinical images was subjectively assessed. RESULTS: Animal experiments showed that the use of O-MAR resulted in accurate CT attenuation, lower AI, better SNR, and higher subjective scores (p < 0.010) at all tube voltages. O-MAR images at 100 kVp had almost the same AI and SNR as non-O-MAR images at 140 kVp. All O-MAR images were scored ≥ 3. In addition, 95% of clinical CT images performed at 100 kVp were considered satisfactory. CONCLUSION: O-MAR can effectively reduce orthopedic metal artifacts at different tube voltages, and facilitates low-tube-voltage CT for patients with orthopedic metal implants.
Animal Experimentation ; Animals ; Artifacts* ; Asian Continental Ancestry Group ; Clinical Study ; Femur ; Humans ; Informed Consent ; Orthopedics* ; Rabbits ; Signal-To-Noise Ratio ; Tomography, X-Ray Computed*

BACKGROUND:There is no simple and effective method to relieve delayed muscle soreness.
OBJECTIVE:To conclude the injured mechanism and therapies of delayed muscle soreness by reviewing literature about damage and repair of the skeletal muscle.
METHODWanfang and PubMed databases (from January 1991 to January 2014) were retrieved for articles
related to morphological structure of the skeletal muscle, mechanism of delayed muscle soreness, and treatment and repair of the skeletal muscle using the keywords of“molecular mechanisms;delayed onset muscle soreness;pain;skeletal muscle;injury”in Chinese and English, respectively. Final y, 24 articles were included in result analysis.
RESULTS AND CONCLUSION:Studies have shown that skeletal muscle injury is related to calcium imbalance, energy imbalance and high concentration of active oxygen. Skeletal muscle injury includes metabolic injury, mechanical injury and inflammatory injury. Insulin-like growth factor, peroxisome proliferator-activated receptorγ-coactivator-1αpromoter and tumor necrosis factorαplay important roles in skeletal muscle repair process. Animal experiments have demonstrated that edaravone may reduce secondary damage and inflammatory infiltration by means of directly preventing rapid peroxidation injury of free radicals in the skeletal muscle. Clinical studies have shown that Chinese medicine preparations, massage and acupuncture can delay the occurrence of exercise-induced muscle injury and fatigue, to improve the speed and quality of the recovery of damaged muscles. The treatment of delayed muscle soreness can achieve satisfactory results by combining physiotherapy with traditional Chinese medicine.

BACKGROUNDLittle is known about the value of (31)P-magnetic resonance spectroscopy ((31)P-MRS) in in vivo assessment of exhaustive exercise-induced injury in skeletal muscle. We aimed to evaluate the value of a (31)P-MRS study using the quadriceps femoris after a single bout of acute exhaustive swimming in rats, and the correlation between (31)P-MRS and histological changes.

METHODSSixty male Sprague-Dawley rats were randomly assigned to control, half-exhaustive, and exhaustive exercise groups. (31)P-MRS of the quadriceps femoris of the right lower limb was performed immediately after swimming exercise to detect Pi, PCr, and β-ATP. The Pi/PCr, Pi/β-ATP, PCr/β-ATP, and PCr/(PCr+Pi) were calculated and pH measured. Areas under the receiver operating characteristic curve (AUCs) were calculated to evaluate the diagnostic potential of (31)P-MRS in identifying and distinguishing the three groups. HE staining, electron microscopy and desmin immunostaining after imaging of the muscle were used as a reference standard. The correlation between (31)P-MRS and the mean absorbance (A value) of desmin staining were analyzed with the Pearson correlation test.

RESULTSPi, PCr, Pi/PCr, and PCr/(PCr+Pi) showed statistically significant intergroup differences (P < 0.05). AUCs of Pi, PCr, Pi/PCr, and PCr/(PCr+Pi) were 0.905, 0.848, 0.930, and 0.930 for the control and half-exhaustive groups, while sensitivity and specificity were 90%/85%, 95%/55%, 95%/80%, and 90%/85%, respectively. The AUCs of Pi, PCr, Pi/PCr and PCr/(PCr+Pi) were 0.995, 0.980, 1.000, and 1.000 for the control and exhaustive groups, while sensitivity and specificity were 95%/90%, 100%/90%, 100%/95%, and 100%/95%, respectively. The AUCs of Pi, PCr, Pi/PCr, and PCr/(PCr+Pi) were 0.735, 0.865, 0.903, and 0.903 for the half-exhaustive and exhaustive groups, while sensitivity and specificity were 80%/60%, 90%/75%, 95%/65%, and 95%/70%, respectively. In the half-exhaustive group, some muscle fibers exhibited edema in HE staining, and the unclear Z-discs and the mitochondria with vacuolar degeneration under electron microscopy. Compared with the half-exhaustive group, muscle fiber edema was increased in the exhaustive group, and the Z-discs were broken and the mitochondria exhibited marked vacuolar degeneration under electron microscopy. There were significant difference in A values of desmin staining in the right vastus lateralis among the control, half-exhaustive, and exhaustive groups with 0.58 ± 0.06, 0.30 ± 0.04, and 0.21 ± 0.02, respectively (P < 0.05). Histological examination also showed injury-induced changes in the vastus lateralis among the different intensities groups. Statistically a moderate correlation between (31)P-MRS and desmin was observed, the correlation coefficients of Pi, PCr, Pi/PCr, and PCr/(PCr+Pi) were -0.706, 0.709, -0.726, and 0.791, respectively (P < 0.01).

CONCLUSIONS(31)P-MRS can effectively reflect the changes in energy metabolism in the skeletal muscle after a single bout of acute exhaustive swimming in rats. Based on the significant correlation between (31)P-MRS parameters and histological changes, the changes of Pi, PCr, Pi/PCr, and PCr/(PCr+Pi) can indirectly reflect the degree of exercise-induced injury.

Animals ; Energy Metabolism ; physiology ; Magnetic Resonance Spectroscopy ; methods ; Male ; Physical Conditioning, Animal ; physiology ; Quadriceps Muscle ; metabolism ; Rats ; Rats, Sprague-Dawley

BACKGROUND:Meniscal root damage is an important reason for meniscus extrusion. In recent years, there are many reports on the relationship between meniscus root injury and meniscus extrusion at abroad, but it is rare at home. OBJECTIVE:To investigate the correlation between knee medial meniscus extrusion and the medial meniscus posterior root tears. METHODS:A retrospective analysis of the MRI and arthroscopic findings of 84 patients with knee medial meniscus extrusion signs was conducted. Medial meniscus extrusion≥ 3 mm or length of medial meniscus extrusion/maximum diameter of meniscus extrusion ≥10%was defined as serious extrusion. The chi-square test analysis was used to analyze the correlation between posterior root tears and the medial meniscus extrusion. RESULTS AND CONCLUSION:MRI measurement results of medial meniscus extrusion (length of medial meniscus extrusion ≥ 3 mm or length of medial meniscus extrusion/maximum diameter of meniscus extrusion≥ 10%) was significantly related with the arthroscopic findings of posterior root tears (P<0.05) with the odds ratio and 95%confidence intervals of 25.04 (3.07-204.44) and 6.96 (1.38-35.19) respectively. The medial meniscus serious extrusion is closely related to posterior root tears of the medial meniscus, which is a significant feature of the meniscus posterior root tears.

Objective To investigate bone age of left-hand wrist in healthy adolescents of Shenyang and Beijing for assessing the process of skeletal development.Methods From 2008 to 2012,1333 adolescents (aged form 4.0 to 18.0 ys) of Shenyang and Beijing were enrolled in this study.Skeletal age was estimated by left hand and wrist X-ray using CHN atlas by 2 qualified radiologists.The correlation between skeletal and chronological age was analyzed using correlation analysis.Skeletal age and chronological age were compared using paired t test.The differences between skeletal and chronological age in genders and regions were compared using independent-samples t test.SPSS for Windows (version 13.0)was used for statistical analysis.P ＜ 0.05 was considered as significant difference.Results (1) Close correlation was found between skeletal age and chronological age (P ＜ 0.01) for both two genders and two regions.(2)Among 28 groups of investigation,16 groups (boys,11 groups) had higher skeletal ages than chronological ages with statistical significance,including Shenyang boys aged 6.0-18.0 ys,Shenyang girls aged 6.0-7.9 ys and 14.0-15.9 ys,Beijing boys at 6.0-15.9 ys and Beijing girls at 8.0-13.9 ys.(3) Comparison between boys and girls:5 groups showed significant difference,including 8.0-9.9 ys,10.0-11.9 ys and 16.0-18.0 ys groups in Shenyang and 6.0-7.9 ys,10.0-11.9 ys groups in Beijing.(4) Comparison between Shenyang and Beijing:6 groups showed statistical significance,including boys at 10.0-11.9 ys,12.0-13.9 ys and 16.0-17.9 ys and girls at 6.0-7.9 ys,8.0-9.9 ys and 10.0-11.9 ys.Conclusion Although CHN atlas method could reflect adolescent bone development,the skeletal age is higher than chronological age in many groups,and the difference between skeletal and chronological age is statistically different between genders and between two regions.This research can be used as a reference for the study of skeletal development and for further emendation of CHN atlas.

Objective To evaluate the value of ice-compression therapy in mice skeletal muscle after acute crush injuries and correlate treatment effect with different compression time by MR DTI. Methods Forty Weistar mice were randomly divided into 4 groups by random number table method: control group (A), 5 min compression time group( B), 15 min compression time group(C) and 30 min compression time group(D). Diffusion tensor imaging examinations were performed before, immediately after, 24, 48 and 72 hours after injuries. ADC and FA values were calculated by fiber tracking tool. The morphological changes were confirmed by histopathology, and immunohistochemical methods were used for the assessment of Desmin expression with mean of A value. Statistical analysis by LSD-t test and Spearman rank correlation.Results (1) For every group before injuries, ADC valueswere (1.38±0.04) ×10-3,(1.38±0.08) ×10-3, ( 1.34 ± 0. 05 ) × 10 -3, ( 1.36 ± 0. 09 ) × 10 -3 mm2/s respectively, FA value were 0. 46 ± 0. 05,0. 45 ±0. 03,0. 45 ± 0. 05,0. 48 ± 0. 04 respectively. ADC values increased significantly and FA values reduced in each group immediately after injuries compared with pre-injury values. ADC values were ( 1.84 ±0. 10) × 10-3, ( 1.79 ±0. 09) × 10-3, ( 1.55 ±0. 07) × 10-3, ( 1.57 ±0. 04) × 10 -3mm2/s respectively,FA value were 0. 21 ±0. 04, 0. 26 ±0. 03, 0. 31 ±0. 02, 0. 30 ±0. 04 respectively. ADC values were still higher and FA values lower than pre-injury values at 24 hours after injury in A, B groups. ADC values were (1.54±0.13) ×10-3, (1.57±0.13) × 10-3mm2/s, FA value were 0.25 ±0.03, 0.26±0.02. (2)DTT showed fibers distorted and the number of fiber bundles reduced, some separation and displacement in each group immediately after injury. C, D groups improved more than A, B groups over time. (3) The disorder arrangement of skeletal muscle cells with edema and filaments separation were found in HE staining after injury, but the degree mitigated in C, D groups. Desmin staining became lighter with fuzzy edge immediately and 24 hours after injury, and changed more than 72 hours after injury. (4) The correlation coefficients of ADC, FA values and A value were respectively - 0. 789 and 0. 763 ( P ＜ 0. 05 ). Conclusions DTI can non-invasively reflect the pathological changes after acute crush injuries of muscles of mice and ice compression therapy. It is a useful method to guide ice compression treatment after acute crush injuries.

Objective To investigate the capillary blood volume (BV) changes in acute ischemic denervated hindlimb of rabbits and the value of 256-slice detector computed tomography (CT) perfusion imaging in evaluation.Methods A total of 40 healthy, adult white rabbits underwent either right hindlimb femoral artery excision combined femoral nerve denervation (combined modeling group, n = 10), simple femoral artery excision (iachemia group, n = 10), simple femoral nerve denervation (denervation group,n = 10), or simple femoral artery separation (sham-surgery group, n = 10).At 1,7, 14, 21, and 28 days following surgery, CT perfusion scanning (Philips Brilliance 256-row) was performed and CT perfusion images were processed using maximum-slope method with Function CT software on EBW workstation.The ratio of BV (rBV) in muscle tissue between right and left hindlimbs was calculated in each group.At 14 and 28 days, following sacrifice, rabbit bilateral adductor was harvested for immunohistochemical staining.The ratio of microvessei density (rMVD) in muscle tissue between right and left hindlimbs was calculated.The significance of the difference of rBV at each time point was assessed using analysis of variance of factorial design (2 ×2).Pearson correlation analysis was used to study the relationship between rBV and rMVD.Results After surgery, the 1st day rBV of combined modeling group, combined modeling group,denervation group and sham-surgery group is 0.31 ± 0.15 ( n = 6), 0.29 ± 0.12 (n = 6), 0.98 ± 0.08 ( n =6), 0.98 ± 0.07 ( n = 6) respectively.The 7th day following surgery rBV is 1.69 ± 0.45 ( n = 5 ), 1.63 ±0.43(n=6), 0.99 ±0.07(n =6), 1.00 ±0.08(n =6).The 14th day is respectively 1.58 ±0.18(n=5), 1.49 ±0.25(n =6), 0.94 ±0.08(n =6), 1.01 ±0.05(n =6).The 21th day is 1.42 ±0.41 (n=4),1.43 ±0.31(n=4), 0.94 ±0.05(n =5), 1.02 ±0.05(n =5),and the 28th day is 1.00 ±0.25(n=4),0.99 ±0.08(n=4), 0.92 ±0.09(n =5), 1.02 ±0.13(n=5).At each time point with exception of postoperative 28 days(F(A) =0.214,P>0.05), ischemia produced main effects on rBV(F(A) =274.268,30.044,65.787,18.886 ,P < 0.01 ), while simple denervation did not show main effects on each time point.Ischemia and denervation did not yield interaction effects on each time point, rMVD from each group supported above-mentioned changes.The correlation coefficient of rBV to rMVD was r = 0.862 ( P < 0.01 ).Conclusions BV in acute ischemic denervated hindlimb of rabbits shows a dynamic change, and denervation does not obviously influence this process.256-slice detector CT perfusion imaging can be used to noninvasively and semi-quantitatively evaluate the dynamic changes of capillary bed in acute ischemie denervated hindlimb of rabbits.