Pelvic step: The contribution of horizontal pelvis rotation to step length in young healthy adults walking on a treadmill

Abstract

Transverse plane pelvis rotations during walking may be regarded as the "first determinant of gait". This would assume that pelvis rotations increase step length, and thereby reduce the vertical movements of the centre of mass-"the pelvic step". We analysed the pelvic step using 20 healthy young male subjects, walking on a treadmill at 1-5 km/h, with normal or big steps. Step length, pelvis rotation amplitude, leg-pelvis relative phase, and the contribution of pelvis rotation to step length were calculated. When speed increased in normal walking, pelvis rotation changed from more out-of-phase to in-phase with the upper leg. Consequently, the contribution of pelvis rotation to step length was negative at lower speeds, switching to positive at 3 km/h. With big steps, leg and pelvis were more in-phase, and the contribution of pelvis rotation to step length was always positive, and relatively large. Still, the overall contribution of pelvis rotations to step length was small, less than 3%. Regression analysis revealed that leg-pelvis relative phase predicted about 60% of the variance of this contribution. The results of the present study suggest that, during normal slow walking, pelvis rotations increase, rather than decrease, the vertical movements of the centre of mass. With large steps, this does not happen, because leg and pelvis are in-phase at all speeds. Finally, it has been suggested that patients with hip flexion limitation may use larger pelvis rotations to increase step length. This, however, may only work as long as the pelvis rotates in-phase with the leg.

Pelvic Rotation Effect on Human Stride Length: Releasing the Constraint of Obstetric Selection

“…While our results show a greater pelvic step length (portion of total step length derived from transverse rotation of pelvis) than reported in previous studies (Sessoms, ; Liang et al, ), the overall pelvic contribution to travel distance in our sample is small, ranging from 2.4% in males at the slower walking speed to 5.1% in females at the faster speed. In obtaining a 5% stride length contribution from the pelvic step, females transversely rotated the pelvis 17° per stride advancing the swing hip an average of 8.5 cm per stride, pelvic mean values more than 50% greater than those obtained for males.…”

“…Horizontal rotations of the pelvis have the potential to do more than minimize and smooth displacement of the COM. For example, at walking speeds greater than 1 ms −1 , pelvic rotation lengthens the step (Liang et al, ). Although not widely studied, yet known since 1965, the effect of pelvic rotation on step length as in COMv displacement is minor (Ducroquet et al, ).…”

“…Although not widely studied, yet known since 1965, the effect of pelvic rotation on step length as in COMv displacement is minor (Ducroquet et al, ). The so‐called “pelvic step” length at self‐selected walking speeds accounted for only 0.3% of total step length in a small mixed‐sex subject pool (Sessoms, ) and a modest 1.8% in a larger all male sample (Liang et al, ). However, as walking speed increases, pelvic step accounts for a greater percentage of total step length and is associated with an increase in amplitude of pelvic rotation (Liang et al, ).…”

“…The so‐called “pelvic step” length at self‐selected walking speeds accounted for only 0.3% of total step length in a small mixed‐sex subject pool (Sessoms, ) and a modest 1.8% in a larger all male sample (Liang et al, ). However, as walking speed increases, pelvic step accounts for a greater percentage of total step length and is associated with an increase in amplitude of pelvic rotation (Liang et al, ). These related phenomena suggest that for a given speed, individuals of varied pelvic width and leg length are likely to differ in their locomotor kinematics.…”

How does external lateral stabilization constrain normal gait, apart from improving medio-lateral gait stability?

“…In line with this, it has been reported that constrained pelvis rotation reduces the energy transfer from lower to upper extremities and subsequently reduces arm swing [16]. Transverse pelvis rotation also reduces vertical center of mass displacement [17] and contributes to step length, but only minimally [18]. Thus, apart from providing medio-lateral gait stability, lateral stabilization devices with constrained transverse pelvis rotation might limit the need to control angular momentum, reduces arm swing, and less likely changes the vertical center of mass displacement and step length.…”