Muscle activity of the TFL was less during squat posture compared to upright posture whereas the activity of the gluteal muscles was greater in the squat posture compared to upright posture. Muscle activity was greater on the stance limb than in the moving limb in both the upright stance and squat postures during resisted side stepping. This increased activity may be due to the fact that the stance limb has to produce sufficient torque to stabilize the pelvis against gravity.Ģ. There were three primary findings of this study:ġ. This procedure was performed in both the upright and squat postures. After side stepping approximately 8 steps, the participant was then asked to step in the opposite direction, eventually stopping at the location at which they started. Then participants moved the other foot so that the feet were once again approximately 30 cm apart. Then, participants were instructed to side step a distance of 1 floor tile (12 inches ) resulting in the feet being approximately 60 cm apart. A resistive elastic band was wrapped around the participant’s ankles and tied so that it was gently stretched to approximately 110% of its full, unstretched length. Three-dimensional knee and hip kinematics were recorded using a 10 camera motion capture system and quantified using the commercially available software.). Participants of this study stood with each foot aligned with the sides of a 12-inch (approximately 30 cm) wide square floor tile. Muscle activity of the TFL and gluteus medius in the stance and moving limbs were measured using a surface EMG system.
The participants for this study included 24 healthy, college aged adults (12 male,12 female, mean +/- SD age, 22.9 +/- 2.9 years height 171.1 +/-10.5 cm mass 68.6 +/- 12.9 kg) who reported having no back, hip, knee, or ankle pain of greater than 2 weeks within the previous year. This study was unique because the researchers compared muscle activation of the TFL and gluteus medius during resisted side stepping in both the upright and squat postures. No previous study compared hip abduction activation in both the squat and upright postures. Only one previous study examined resisted side stepping with patients maintaining an upright posture and only one other study examined resisted side stepping with patients in a squat posture. According to the authors, only two previous studies specifically measured gluteus medius and tensor fascia lata muscle activation during resisted side stepping. Previous studies investigated the maximum voluntary isometric contraction of various hip abduction exercises including resisted side stepping, sidelying hip abduction, as well as weight-bearing and non-weight bearing standing hip abduction. The purpose of this study was to examine hip abductor muscle activity and hip and knee joint kinematics during resisted side stepping in order to determine the level of muscle activation in both the stance and moving limbs and the effect of posture during this exercise.
2015 45: 675-682 Article summary by Rachel Berry, SPT from Missouri State University, Springfield, Missouri
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