The Effects of Changes in Upper Limb Loads on the Activity of the Gluteus Medius Muscle in Single Limb Support

Abstract

Balance is an ability to have major effects on theperformance of all activities in daily living to main -tain the body in equilibrium(1, 2). Balance is a com -plex motor control work that include the integrationof sensory information, processing by the nervoussystem, and biomechanical factors(3). Three func -tional elements, that is, support by the muscu -loskeletal system which is the biomechanical aspectof the body, motor functions including motor coordi-nation, and integrated actions of sensory functionsare necessary for normal balance responses tooccur(4). The body can maintain balance only wheninternal force(muscle contraction, etc.) acts againstpostural changes caused by external forces(gravity,inertia, ground reaction forces, etc.)(5).The gluteus medius muscle is a representative hipjoint abductor muscle and is an important antigrav -ity muscle. This is a fan-shaped muscle extendingfrom the crista iliaca of the pelvis to the greatertrochanter of the femur which beings to contract atthe end stage of the swing phase, contracts maxi-mally during the mid stance phase. It contractsefferently to prevent the pelvis from dropping duringthe swing phase(6). If the gluteus medius muscle isweek or the beginning of hip joint abduction move -ments is suppressed, hip hiking deformation willoccur. Therefore, if the gluteus medius muscle isweakened or suppressed, walking will be damaged orrestricted(7). Patients with weak gluteus mediusmuscles cannot maintain pelvic stability, become tohave problems in walking as a results, and graduallydevelop low back pain, buttock pain, and greatertrochanter bursitis, etc. When the low back pain offemales with weak gluteus medius muscles wasidentified through physical tests and the weak glu -teus medius muscles were treated with appropriaterehabilitation programs, the pain of patients withweak gluteus medius muscles was graduallyrelieved(8). The gluteus medius muscle is maximallyactivated when the hip joint is abducted or internallyrotated. The gluteus medius muscle's isotonic abduc -tion and internal rotation movements in single limbsupport are very effective in the early stage of neu -romuscular rehabilitation. Therefore, those move -ments should be made very importantly in the earlystage of rehabilitation and rotation and functionalmovement patterns should be added to the hipjoint(9).