The Influence Of Different Weight-bearing Modes On The Balance Of Dynamic And Static Posture And Analysis Of Vulnerability To Shoulder And Neck Injuries

Postural stability is a crucial issue that requiring high level of body balance to maintain performance during quiet standing,locomotion,and any activities.Most college students frequently and daily carry items with backpack or shopping bags while walking from or to classes and,also to restaurants,stores,market and bars or parties.It can cause different level of damage to human body if loading for a long time.Purpose:To examine the effect of holding or carrying different loads on balance platform while standing and subsequent postural sway on medial-lateral direction whilst walking and stepping from a simulated kerb.To explore the correlation between the vulnerability of the shoulder-neck and the balance ability in a stationary and upright situation.Method: Fifteen healthy young adults(age=24.1±1.4 years;height=1.67±0.10m;mass=60.4±11.3kg,BMI 21.4±2.2 kg/m2)participated in the study and the static postural control was assessed using the AMTI System with a 50 Hz sampling rate in the standing,walking,and stepping for 40 s.Nine conditions during the three simulated situations were performed for each test,thus in total 27 trials were conducted for each participant completing entire experiment.The nine conditions including no load,10%BWbackpack,20%BWbackpack,10%BWsingle-bag,20%BWsingle-bag,10%BWboth-hand carriage,20%BWboth-hand carriage,10%BWsingle-hand carriage and 20%BWsingle-hand carriage.Statistical Analysis was performed using the SPSS statistical package(version 24.0).Conclusion:1.The effect of load conditions was statistically significant difference in both medial/lateral direction and anterior/ posterior direction of postural sway.2.It should be suggested that young adults should wear backpack no more than 10%BW because the postural sway may be significantly increased in sagittal plane with any loads over10%BW.3.Loading asymmetrically behave more unstable than loading symmetrically in balance control.4.There was no significant interaction between loading conditions and gender both in the A/P direction and the M/L direction.But young women may have higher falls risk than young man with asymmetrical loading carriage.Especially,it should not be advised to carry loads over 20%BW asymmetrically for them.5.Shoulder-neck pain may lead to unstable balance ability with incremental magnitude of loads.