Study On The Protective Effect Of Parachute Ankle Brace In Landing Of Airborne Soldiers

With the increase of training intensity and difficulty of airborne troops,the problem of musculoskeletal disorders of airborne troops has become more and more prominent,and the injury of ankle joint has seriously affected the health of airborne commanders and the combat effectiveness of troops.Parachute ankle brace(PAB)has been widely used in foreign airborne troops.In this study,we evaluated the protective effect of one type PAB and analyzed the effects of different factors on muscle electromyographic activity around the ankle joint and ankle stability during landing,in order to provide a theoretical basis for preventing and reducing injuries to the musculoskeletal system of the ankle joint caused by airborne soldier training.Objective To study the protective effect of one type PAB on the ankle joint during the half-squat Parachute Landing phase of simulated parachute jump,and to provide a theoretical basis for the prevention and reduction of musculoskeletal system injuries of the ankle joint caused by airborne training.Methods Thirty male airborne soldiers were selected to jump from a 1.5m and2.0m height jumping platform and land on the sand in a half-squat parachute landing position with PAB on(experimental group)and without PAB on(control group).The experiment was divided into 1.5m experimental and control groups versus 2.0m experimental and control groups.The postural angle sensor and surface electromyography were applied to measure the tilted angle of the ankle joint coronal plane,root mean square(RMS)and maximum voluntary contraction(MVC%)of the muscles around the ankle joint,respectively.The ankle joint protection effect of this type of PAB was evaluated.Results(1)At the same height,the tilted angle of the ankle joint coronal surface in the experimental group was reduced compared with that in the control group,and the difference was statistically significant(P < 0.05).Under the same protection condition,the ankle coronal tilt angle in the 1.5m group was reduced compared with that in the 2.0m group,and the difference was statistically significant(P<0.05).The ankle coronal tilt angle in the 2.0m experimental group was less than that in the 1.5m control group,and the difference was statistically significant(P<0.05).The factors influencing the ankle coronal tilt angle were protection status,jump height and body weight in descending order(P < 0.05).(2)The RMS values of the right anterior tibialis and bilateral lateral gastrocnemius muscles decreased in the 1.5m experimental group compared with the 1.5m control group,while the RMS values of the bilateral peroneal longus muscles increased,and the difference was statistically significant(P<0.05).The RMS values of the bilateral anterior tibialis and bilateral lateral gastrocnemius muscles decreased in the 2.0m experimental group compared with the 2.0m control group,and the RMS values of the bilateral peroneal longus muscles increased;the difference was statistically significant(P<0.05).The RMS values of the right anterior tibialis,bilateral lateral gastrocnemius muscles and right peroneus longus muscle were reduced in the 1.5m experimental group compared to the 2.0m experimental group,and the difference was statistically significant(P <0.05).The RMS values of the bilateral anterior tibialis,bilateral lateral gastrocnemius muscles and right peroneus longus muscle were reduced in the 1.5m control group compared to the 2.0m control group,and the difference was statistically significant(P< 0.05).(3)The MVC% values of the right anterior tibialis and bilateral lateral gastrocnemius muscles decreased in the 1.5m experimental group compared to the1.5m control group,while the MVC% values of the bilateral gastrocnemius longus muscles increased,and the difference was statistically significant(P < 0.05).The MVC% values of the bilateral anterior tibialis and right lateral gastrocnemius muscle decreased in the 2.0m experimental group compared to the 2.0m control group,and the MVC% values of the bilateral gastrocnemius longus muscles increased,and the difference was statistically significant(P < 0.05).The MVC% values of bilateral anterior tibialis,bilateral lateral gastrocnemius muscles and right peroneal longus muscle were reduced in the 1.5m experimental group compared with the 2.0m experimental group,and the difference was statistically significant(P < 0.05).The MVC% values of bilateral anterior tibialis,right lateral gastrocnemius muscle and right peroneal longus muscle were reduced in the 1.5m control group compared with the 2.0m control group,and the difference was statistically significant(P<0.05).(4)The factors influencing the RMS and MVC% values of the anterior tibialis,lateral gastrocnemius muscle and peroneus longus muscle were mainly protection status and jump height,and body weight also influenced the RMS and MVC% values of the right peroneus longus muscle(P<0.05).(5)In the control group,there was a positive trend of correlation between the RMS and MVC% values of the anterior tibialis and peroneus longus muscle and the angle values;the difference was statistically significant(P<0.05).Conclusion(1)Wearing PAB during landing can provide effective protection for the ankle joint,improve the stability of the ankle joint,and reduce the load on the muscles around the ankle joint.(2)The ankle joint load during landing of airborne soldiers is influenced by protection level,the height of the jumping platform and body weight.(3)When landing at 2.0m height,the muscle load around the ankle joint is at a very high level.