BACKGROUND:Static stretching effectively improves joint motion amplitude,dynamic stretching effectively improves muscle strength and athletic performance through the post-activation strengthening effect of the muscles.OBJECTIVE:To explore the immediate effects of different stretching methods on knee joint muscle strength and vertical jump performance,and provide theoretical support for seeking the best stretching plan,improving sports performance,and preventing training injuries.METHODS:Thirty healthy college students were randomly recruited.The Biodex isokinetic muscle strength system,Qualisys infrared motion capture system,and AMTI three-dimensional force measurement platform were used to collect knee joint muscle strength and vertical jump data after static quadriceps/hamstring stretching,dynamic quadriceps/hamstring stretching,dynamic quadriceps/static hamstring stretching,and static quadriceps/dynamic hamstring stretching.The peak torque,average power,vertical jump height,peak vertical ground reaction force,and joint motion amplitude of the knee joint were used to evaluate the muscle strength and vertical jump performance of the knee joint.RESULTS AND CONCLUSION:Compared with the static quadriceps/hamstring stretching,dynamic quadriceps/hamstring stretching significantly increased knee joint peak torque,average power,and vertical jump height(P<0.05);dynamic quadriceps/static hamstring stretching and static quadriceps/dynamic hamstring stretching significantly increased knee extension and flexion peak torque and average power(P<0.05).Compared with static quadriceps/hamstring stretching,second peak vertical ground reaction force significantly decreased after static quadriceps/dynamic hamstring stretching(P<0.05);lower limb joint motion amplitude significantly increased after dynamic quadriceps/hamstring stretching(P<0.05).These findings indicate that immediate agonists/antagonistic muscle dynamic stretching and agonists dynamic stretching/antagonistic muscle static stretching significantly improve knee joint muscle strength,vertical jump performance,and joint motion amplitude.A larger joint motion amplitude is beneficial for improving athletic performance and better absorbing ground impact during landing.At the same time,agonists muscle dynamic stretching/antagonistic muscle static stretching is better than agonists/antagonistic muscle dynamic stretching to improve knee joint muscle strength,and agonists muscle static stretching/antagonistic muscle dynamic stretching is beneficial for improving the energy absorption capacity during vertical jumping and reducing the risk of injury during landing.

BACKGROUND:Static stretching effectively improves joint motion amplitude,dynamic stretching effectively improves muscle strength and athletic performance through the post-activation strengthening effect of the muscles.OBJECTIVE:To explore the immediate effects of different stretching methods on knee joint muscle strength and vertical jump performance,and provide theoretical support for seeking the best stretching plan,improving sports performance,and preventing training injuries.METHODS:Thirty healthy college students were randomly recruited.The Biodex isokinetic muscle strength system,Qualisys infrared motion capture system,and AMTI three-dimensional force measurement platform were used to collect knee joint muscle strength and vertical jump data after static quadriceps/hamstring stretching,dynamic quadriceps/hamstring stretching,dynamic quadriceps/static hamstring stretching,and static quadriceps/dynamic hamstring stretching.The peak torque,average power,vertical jump height,peak vertical ground reaction force,and joint motion amplitude of the knee joint were used to evaluate the muscle strength and vertical jump performance of the knee joint.RESULTS AND CONCLUSION:Compared with the static quadriceps/hamstring stretching,dynamic quadriceps/hamstring stretching significantly increased knee joint peak torque,average power,and vertical jump height(P<0.05);dynamic quadriceps/static hamstring stretching and static quadriceps/dynamic hamstring stretching significantly increased knee extension and flexion peak torque and average power(P<0.05).Compared with static quadriceps/hamstring stretching,second peak vertical ground reaction force significantly decreased after static quadriceps/dynamic hamstring stretching(P<0.05);lower limb joint motion amplitude significantly increased after dynamic quadriceps/hamstring stretching(P<0.05).These findings indicate that immediate agonists/antagonistic muscle dynamic stretching and agonists dynamic stretching/antagonistic muscle static stretching significantly improve knee joint muscle strength,vertical jump performance,and joint motion amplitude.A larger joint motion amplitude is beneficial for improving athletic performance and better absorbing ground impact during landing.At the same time,agonists muscle dynamic stretching/antagonistic muscle static stretching is better than agonists/antagonistic muscle dynamic stretching to improve knee joint muscle strength,and agonists muscle static stretching/antagonistic muscle dynamic stretching is beneficial for improving the energy absorption capacity during vertical jumping and reducing the risk of injury during landing.

Thermoacoustic imaging (TAI) is a new non-invasive, non-ionization and nondestructive modality capable of high microwave contrast and high ultrasound resolution, and it has attracted extensive attention in recent years. This review introduces the technical principle, imaging system and imaging characteristics of TAI, and then introduces the application of TAI for breast cancer detection as an example. This review introduces the advantages of TAI in solving corresponding clinical problems in view of its high resolution and high contrast. In addition, it also explains the roles of TAI in medical diagnosis and treatment. Finally, the potential applications of TAI in medical diagnosis is introduced from many aspects and multiple perspectives. The future development of TAI in the challenges of current medical diagnosis is also prospected.
Acoustics ; Breast Neoplasms ; diagnostic imaging ; Diagnostic Imaging ; methods ; Humans ; Microwaves

To investigate the effects of telmisartan on steatohepatitis (NASH) in rats by activating peroxisome proliferator-activated receptor gamma (r). Thirty male SD rats were randomized into normal control group, NASH control group and telmisartan prevention group. Normal control group was given standard food and the other two groups were given high fat diet for 16 weeks to induce NASH. Prevention group was given telmisartan (5 mg.kg-1.d-1) for 4 weeks by intragastric adminstration after 12 weeks. At the end of the 16th week, all the rats were sacrificed. Pathological changes of liver were observed by optical microscopy. Serum alanine aminotransferase(ALT), aspartate aminotransferase(AST), fasting blood glucose(FBG), fasting insulin(FINS), HOMA-IR(homeostasis model assessment insulin resistance), Serum TNF-a and adiponectin were detected and analyzed.Western blot and RT-PCR were used to detect PPARr expression in hepatic tissues on protein and mRNA levels. (1) Rats were successfully modeled. The liver tissue samples were divided into 4 degrees (F0 - 4) based on total fatty degeneration of liver cells.There was one rat reached F3 and nine rats reached F4 in NASH group, one rat reached F1, six rats reached F2 and three rats reached F3 in prevention group. Inflammatory activity scores of hepatic tissues in the model group were 2.67+/-0.25, while that in the control group was 0 (U=15 and P is less than to 0.01), in the prevention group were 2.67+/-0.25 and 1.36+/-0.12 (U=24 and P is less than to 0.05 ). (2) The levels of serum ALT, AST, FBG, FINS, TNFa and HOMA-IR in the model group were increased than those in the control group( the vaules of q were 13.130, 6.472, 6.909, 26.619, 14.591 and 49.683 respectively, P less than 0.01). The levels of serum ALT, FINS, FBG, TNFa and HOMA-IR in the prevention group were decreased as compared to the model group (the vaules of q were 7.024, 4.145, 14.829, 13.195 and 31.991 respectively, P less than 0.01 ). (3) The serum adiponectin, PPARrmRNA and protein in liver tissues of the model group were lower than those in the control group (q values were 10.696, 8.679 and 16.762 respectively, P is less than to 0.05).The data in the prevention group were higher as compared to the model group(q values were 3.879,3.079,6.400, P is less than to 0.05 respectively). HOMA-IR was positively correlated with the expression of TNFa but negatively correlated with the expression of adiponectin (r = 0.927, P is less than to 0.01; r = -0.891, P is less than to 0.01, respectively). Telmisartan may has preventive effect on rats with steatohepatitis (NASH) by a mechanism of activating peroxisome proliferator-activated receptor r.
Alanine Transaminase ; blood ; Animals ; Aspartate Aminotransferases ; blood ; Fatty Liver ; Insulin Resistance ; Non-alcoholic Fatty Liver Disease ; Rats ; Rats, Sprague-Dawley