The effect of breast support on the kinematics of the breast during the running gait cycle

Abstract

Although breast pain has been related to vertical breast displacement and velocity, the influence of breast support on multi-planar breast kinematics and breast comfort has yet to be ascertained. The aims of this study were to investigate multi-planar breast displacement, velocity, and acceleration with and without breast support during running and to establish the correlation with breast comfort. Fifteen females ran at 2.8 m x s(-1) in no bra, an everyday bra, and a sports bra. Three-dimensional coordinates of breast and body markers were tracked during ten gait cycles and following each trial the participants rated their breast comfort. Relative breast displacement was calculated and derived for velocity and acceleration. Vertical breast displacement, velocity, and acceleration peaked at, before, and after mid-stance, respectively. The patterns of displacement and velocity trajectories were unaffected by increasing breast support, though the magnitudes were significantly reduced. The magnitude and trajectory of breast acceleration was unaffected by increasing breast support and showed no correlation with comfort. Breast velocity displayed the strongest relationship to comfort (r = 0.61). Considerable mediolateral and anteroposterior breast kinematics were identified, suggesting that future studies and bra design may benefit from three-dimensional analysis. In conclusion, improvements in breast support may be defined by reductions in breast velocity and displacement.

A method to estimate strain in the breast during exercise

“…When no bra was used, markers were positioned on the right nipple, and the suprasternal notch (the junction of the sternum and the clavicles). When a bra was worn, the nipple marker was repositioned on the bra over the nipple with the assumption that there was no relative motion between the bra surface and the skin [6,[19][20][21][22][23]. The global coordinate system was defined with respect to the laboratory with the positive vertical coordinate in the upward direction and co-ordinates were measured to an accuracy of ±0.25 mm.…”

The influence of breast support on torso, pelvis and arm kinematics during a five kilometer treadmill run

“…These two breast supports were selected based upon their use within previous breast biomechanics literature (Scurr et al, 2010). Participants selected a maintainable running speed, commonly employed during training, this ranged from 8.5 km h À1 to 10.5 km h À1 , with an average of 9 km h À1 (1 km h À1 ).…”

“…Multiple tracking markers were positioned on the torso segment due to the potential obscuring of these markers in the two breast support conditions. In order to calculate the compression and elevation provided by each breast support a marker was positioned on the bras directly over the nipple (Scurr et al, 2010). Further to this, to track and identify the phases of the gait cycle, an additional marker was positioned on the left heel of each participant's trainer (Zeni, Richards, & Higginson, 2008).…”

“…Fourteen retro-reflective hemi-spherical markers (diameter of 12 mm) were positioned with hyper-allergenic tape on the anatomical landmarks which defined the segment end points and additional tracking markers for each segment (Visual3D, C-motion Inc.), detailed in Table 1. One additional marker was positioned directly over the right nipple on top of the bra, in the two breast support conditions (Scurr et al, 2010). Multiple tracking markers were positioned on the torso segment due to the potential obscuring of these markers in the two breast support conditions.…”

“…To eliminate the influence of torso orientation on the breast ROM, compression and elevation calculations, the global nipple coordinates were converted to relative nipple coordinates (relative to the torso origin) using a transformation matrix within Visual3D Scurr et al 2010), Pelvis markers (Schache et al 2001, Visual3D, C-motion Inc. marker set recommendations), Upper arm markers (Visual3D, C-motion Inc. marker set recommendations).…”