ABSTRACT
Objective: To study the protective effect of parachute ankle brace on ankle joint during simulated parachuting landing. Methods: In August 2021, 30 male paratroopers were selected as the test subjects by simple random sampling method. They jumped from the 1.5 m and 2.0 m height platforms respectively with and without parachute ankle brace, and landed on the sandy ground in a semi-squat parachute landing position. The experiment was divided into 1.5 m experimental group and control group and 2.0 m experimental group and control group. Angle sensor and surface electromyograph were used to measure and analyze the coronal tilt range of the ankle joint and the percentage of maximal voluntary contraction (MVE%) of the muscles around the ankle joint, respectively, to evaluate the protective effect of the parachute ankle brace. Results: At the same height, the tilt range of coronal plane of ankle in experimental group was significantly reduced compared with control group, and the difference was statistically significant (P<0.05). Under the same protection state, the tilt range of the coronal plane of the ankle in the 1.5 m group was significantly reduced compared with that in the 2.0 m group, and the difference was statistically significant (P<0.05). The coronal plane inclination range of the ankle in 2 m experimental group was significantly lower than that in 1.5 m control group, and the difference was statistically significant (P<0.05). Compared with 1.5 m control group, MVE% of right tibialis anterior muscle and bilateral lateral gastrocnemius decreased in 1.5 m experimental group, while MVE% of bilateral peroneus longus increased, with statistical significance (P<0.05). Compared with 2.0 m control group, the MVE% of bilateral tibialis anterior muscle and right lateral gastrocnemius decreased in 2.0 m experimental group, while the MVE% of bilateral peroneus longus increased, with statistical significance (P<0.05). The MVE% of bilateral tibialis anterior muscle, bilateral lateral gastrocnemius muscle and right peroneus longus muscle in 1.5 m experimental group decreased compared with 2.0 m experimental group, and the differences were statistically significant (P<0.05). Compared with 2.0 m control group, the MVE% of bilateral tibialis anterior muscle, right lateral gastrocnemius muscle and right peroneus longus muscle in 1.5 m control group decreased, and the differences were statistically significant (P<0.05) . Conclusion: Wearing parachute ankle brace can effectively limit the coronal plane inclination range of ankle joint, improve the stability of ankle joint and reduce the load on the muscles around ankle joint by landing. Reducing the height of the jumping platform can reduce the coronal plane incline range of the ankle and the muscle load around the ankle during landing.
Subject(s)
Humans , Male , Ankle , Ankle Joint/physiology , Lower Extremity/physiology , Muscle, Skeletal/physiology , ElectromyographyABSTRACT
Objective To analyze the correlation factors between CT imaging features of pulmonary embolism(PE)and clinical severity stratification,to explore the value of CT pulmonary angiography (CTPA)in acute PE severity stratification.Methods According to the clinical severity,48 patients with acute PE proved by CTPA were classified into two groups,including 21 critical and 27 non-critical patients. Embolism index,ratio of central pulmonary involvement,ratio of right ventricle maximum minor axis (RVMMA)to left ventricle maximum minor axis(LVMMA),namely RV:LV,dilation of main pulmonary and/or right pulmonary trunk,and dilation of bronchial arteries in both groups were analyzed comparatively. The correlation factors between CT imaging features and PE clinical severity stratification were explored.The correlation between RV:LV and embolism index of 48 patients was analyzed.Results Pulmonary embolism index(22.0%—85.0%,median 38.0%),ratio of central pulmonary involvement(42.5%),RV:LV (0.90—1.90,median 1.30),dilation of pulmonary artery(14 cases),and dilation of bronchial artery (8 cases)in critical group(21 cases)were higher than those corresponding factors(5%—48%,median 21.5%,31.25%,0.80—1.40,median 1.00,5 eases,and 3 eases)in non-critical group(27 cases) (Z=4.27,X~2=5.40,Z=2.58,X~2=11.45,X~2=4.87,P