Effects of hip and trunk muscle strengthening on hip function and lower limb kinematics during step-down task.
BACKGROUND
Strengthening of the hip and trunk muscles has the potential to change lower limb kinematic patterns, such as excessive hip medial rotation and adduction during weight-bearing tasks. This study aimed to investigate the effect of hip and trunk muscles strengthening on hip muscle performance, hip passive properties, and lower limb kinematics during step-down task in women.


METHODS
Thirty-four young women who demonstrated dynamic knee valgus during step-down were divided into two groups. The experimental group underwent three weekly sessions of strengthening exercises for eight weeks, and the control group continued their usual activities. The following evaluations were carried out: (a) isokinetic maximum concentric and eccentric work of hip lateral rotators, (b) isokinetic hip passive torque of lateral rotation and resting transverse plane position, and (c) three-dimensional kinematics of the lower limb during step-down.


RESULTS
The strengthening program increased concentric (P<0.001) and eccentric (P<0.001) work of hip lateral rotators, and changed hip resting position toward lateral rotation (P<0.001). The intervention did not significantly change hip passive torque (P=0.089, main effect). The program reduced hip (P=0.002), thigh (P=0.024) and shank (P=0.005) adduction during step-down task. Hip, thigh and knee kinematics in transverse plane and foot kinematics in frontal plane did not significantly modify after intervention (P≥0.069, main effect).


CONCLUSIONS
Hip and trunk strengthening reduced lower limb adduction during step-down. The changes in hip maximum work and resting position may have contributed to the observed kinematic effects.
Department of Physical Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil. Electronic address: laraujo.vanessa@gmail.com.
Vanessa Lara
VL
Araújo
Department of Physical Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Thales Rezende
TR
Souza
Department of Physical Therapy, Faculdade UNA de Bom Despacho, Bom Despacho, Minas Gerais, Brazil.
Viviane Otoni do Carmo
VODC
Carvalhais
Department of Physical Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Aline Castro
AC
Cruz
Department of Physical Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil. Electronic address: sfonseca@ufmg.br.
Sérgio Teixeira
ST
Fonseca
D000328:Adult; D001696:Biomechanical Phenomena; D005081:Exercise Therapy / Q000379:methods; D005260:Female; D006615:Hip / Q000502:physiology*; D006621:Hip Joint / Q000503:physiopathology; D006801:Humans; D007717:Knee / Q000502:physiology; D007719:Knee Joint / Q000502:physiology; D035002:Lower Extremity / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D016474:Weight-Bearing; D055815:Young Adult
Kinematics; Lower limb; Muscle work; Passive torque; Step-down task; Strengthening