Breast Kinematics Research Articles

Vertical Breast Displacement in Asian Women During Exercise: influence of Bra Type, Size and Different Parts of the Breast

Abstract Asian women have smaller breast sizes and greater breast density, which suggests specific research on their breast kinematics and biomechanics. To investigate vertical breast displacement of Asian women among exercise modalities (rope skipping, walking, jogging, running) in different support conditions (wearing everyday bra or sports bra), and assess the motion between different parts of the breast, seven participants were selected to participate in this study. Five infrared markers were placed on each of their left breasts, and a three-dimensional motion capture system (NDI Optotrak Investigator) was used to collect the data on vertical breast displacement during walking (5 km/h), jogging (7.5 km/h), running (10 km/h) and rope skipping (2 Hz). No significant difference was found in the vertical displacement of different parts of the breast in the two bra conditions. Also, there was significant difference in vertical breast displacement among rope skipping, jogging and running. Breast size did not significantly affect its vertical displacement. The smaller, denser breast appears to reach a threshold of vertical displacement that is similar at high severities of dynamic exercises (jogging, running and rope skipping). The results might be useful for designing special sports bras for Asian women with small breasts or rope skipping participants to improve the shock absorption function.

A hybrid forecasting model for ageing breast deformation during yoga practice

In this work, the deformation of bilateral breasts was investigated with an established hybrid model to predict the nipple movement specifically for senior women during yoga exercise. A motion capture system was used to collect the displacement of 10 markers on the breasts from 11 senior women (average age of 62) during yoga practice and then the data were analyzed by integrating the absolute grey relation analysis (AGRA) and extreme learning machine (ELM). The right and left breasts had the maximum motion amplitude in the horizontal direction but they were respectively featured with contraction and extension during yoga practice. AGRA showed that the nipple motion was highly associated with the vertical region above the nipple for the left breast but the parallel region along with the nipple for the right breast. The ELM model is able to predict the nipple movement within tolerable error (∼0.0037). This study lays a foundation for a better understanding of ageing breast kinematics during yoga poses with limited practical experiments. Besides, the accurate and efficient results can be used not only for yoga pose instruction but also for ergonomic sports bra design.

A novel multi-study intervention investigating the short and long term effects of a posture bra on whole body and breast kinematics

BackgroundPoor standing posture has been reported in women with larger breasts, increasing the risk of back pain. Whilst breast reduction surgery can improve posture, conservative measures such as special bras may offer short or long-term relief of symptoms without surgical intervention. Research questionThis study aimed to utilise a multi-study intervention to investigate the short and long-term kinematic effects of wearing a posture bra. MethodsStudy one utilised biomechanics and physiotherapy expertise to modify the design of a prototype bra to improve posture and breast kinematics; resulting in a second-generation posture bra. To test this bra, 24 females were randomly assigned to control and intervention groups. The control group wore their everyday bra; the intervention group wore the generation 2 posture bra in place of their everyday bra for three months. Pre and post intervention, posture (spine curvature, scapula position, whole body alignment) and breast kinematics were assessed during sitting, standing and walking. Short-term effects of the posture bra were compared to an everyday bra and no bra (study two), whilst the long-term effects were compared using the no bra condition (study three). ResultsBiomechanical intervention improved posture and breast kinematics in a prototype posture bra resulting in a second-generation prototype. Pre-intervention, the generation 2 posture bra significantly improved scapula retraction by 6° during both sitting and standing, but also increased deviation of whole body alignment compared to everyday bra and no bra conditions. During walking the posture bra reduced breast motion by 17 % compared to the everyday bra. Following the three-month wearer intervention, scapula depression significantly improved in the intervention group. SignificanceA biomechanically informed posture bra was able to effectively support the breasts and improve scapula position without compromising spinal curvature, reducing the risk of musculoskeletal pain associated with poor posture.

The detection of the upper boundary of breasts using 4D scanning technology

ABSTRACT Anthropometric measurements such as breast volume are directly associated with the product development for bras. However, a non-contact method that accurately detects the upper boundary of breasts has not been reported. By taking advantage of the time delay in the vertical displacement between the breasts and the chest wall during physical activity, we 4D-scanned 26 female participants using Temporal 3dMD system and proposed a method to visualise the amount of variability for this relative displacement, so as to reveal the upper boundary of breasts on static 3D body scans. This is also one of the first studies that investigate the vertical displacement and the shape deformation of breasts during running using 4D scanning technology. Ultimately, the method and results can increase the understanding of breast kinematics, and benefit the product design of bras, especially for sports bras, and other products for women that require a close fit to the torso.

Effects of Breast Motion on Lower-Body Kinematics during Running

We measured the effects of breast motion on lower-body kinematics during overground running. Thirty female participants aged 18–60 years completed two blocks of three trials each of overground running for 25 m at self-selected pace under two conditions: with and without breast support provided by a sports bra. Participants' body movements were analyzed with 18 parameters characterizing breast and lower-body kinematics. Sports bra use reduced breast motion and increased about 83% of the lower-body kinematic parameters, including running velocity; stride length; foot clearance; vertical and lateral center of mass displacement; and thorax, hip, knee, and ankle range of motion (all p < 0.05). Among the changed characteristics, the stride length, center of mass displacements, thorax and knee range of motions correlated negatively (r = –0.25 to –0.46) with the velocity of breast motion. Therefore, the reduction of breast motion may improve lower-body kinematics during running, which may influence sport and leisure performance.

The Kinematics of Breasts Implanted With a Reduced Mass Implant: A Pilot Study.

Breast implants may increase breast skin tension and interact with surrounding tissues to alter breast position and motion during dynamic activity. Reducing implant mass and changing implant location (submuscular/subglandular) may also affect breast kinematics and the subsequent loads on breast structures. The aim of this pilot study was to describe the kinematics of breasts augmented with reduced-mass implants during standing, walking, and running, compared with natural breasts, and to provide insight into how implant location (submuscular/subglandular) alters breast kinematics. Two breast augmentation participants (12-15 months postsurgery: 32AA presurgery, anatomical submuscular 255 cc B-Lite reduced-mass implant; 32A presurgery, anatomical subglandular 285 cc B-Lite reduced-mass implant) and 2 natural-breasted participants of similar breast size and anthropometrics were recruited. Nipple and torso positional data were recorded with electromagnetic sensors during standing, walking, and running. Nipple kinematics relative to the torso were calculated. The B-Lite participants both displayed greater nipple projection and elevation during standing and a 50% reduction in nipple acceleration during walking, when compared with their natural counterparts. During running, the B-Lite subglandular participant displayed decreased nipple kinematics compared with her natural counterpart and lower nipple kinematics compared with the B-Lite submuscular participant during walking and running. A combination of implant location (subglandular) and reduced mass minimized nipple kinematics during running. Reducing nipple kinematics during dynamic activity may decrease the loading on breast structures, helping to decrease ptosis and increase the longevity of procedure outcomes.

Understanding key performance indicators for breast support: An analysis of breast support effects on biomechanical, physiological and subjective measures during running

ABSTRACTTo assess the effectiveness of breast support previous studies monitored breast kinematics and kinetics, subjective feedback, muscle activity (EMG), ground reaction forces (GRFs) and physiological measures in isolation. Comparing these variables within one study will establish the key performance variables that distinguish between breast supports during activities such as running. This study investigates the effects of changes in breast support on biomechanical, physiological and subjective measures during running. Ten females (34D) ran for 10 min in high and low breast supports, and for 2 min bare breasted (2.8 m·s−1). Breast and body kinematics, EMG, expired air and heart rate were recorded. GRFs were recorded during 10 m overground runs (2.8 m·s−1) and subjective feedback obtained after each condition. Of the 62 variables measured, 22 kinematic and subjective variables were influenced by changes in breast support. Willingness to exercise, time lag and superio-inferior breast velocity were most affected. GRFs, EMG and physiological variables were unaffected by breast support changes during running. Breast displacement reduction, although previously advocated, was not the most sensitive variable to breast support changes during running. Instead breast support products should be assessed using a battery of performance indicators, including the key kinematic and subjective variables identified here.

Trunk marker sets and the subsequent calculation of trunk and breast kinematics during treadmill running

Female participants present a unique challenge as the design of the bra used to support the breasts occludes the correct positioning of many recommended trunk marker sets. This study aimed to compare the effect of two existing and one new trunk marker set on the calculation of trunk and breast kinematics. Twelve females had markers placed on their trunk and right nipple; these markers were tracked using infrared cameras during five running gait cycles and used to define three trunk calculation methods: Trunk 1: suprasternal notch, right and left ribs; Trunk 2: supersternal notch, processus xiphoideus, 7th cervical and 8th thoracic spinous process; Trunk 3: Trunk 2 plus a marker 33% from the suprasternal notch to the processus xiphoideus, and another 50% between the 7th cervical and 8th thoracic spinous process. Trunk segment capture success, segment origin instability, segmental residual, trunk kinematics, and breast range of motion (relative to the trunk segment), were calculated for each trunk segment. Segment capture success varied from 88% (Trunk 1) to 100% (Trunk 2 and 3). Segment origin instability ranged from 0.2 cm (Trunk 2 and 3) to 1.5 cm (Trunk 1). Maximum trunk extension differed by 7° and breast range of motion varied by 41% (anterioposterior), 54% (mediolateral), and 21% (superioinferior) between trunk calculation methods. The selection of marker set used to construct the trunk segment is critical before recommending improvements to bra design to improve breast support. The Trunk 3 marker set is recommended for subsequent breast research.

Breast Support Garments are Ineffective at Reducing Breast Motion During an Aqua Aerobics Jumping Exercise.

The buoyant forces of water during aquatic exercise may provide a form of ‘natural’ breast support and help to minimise breast motion and alleviate exercise induced breast pain. Six larger-breasted females performed standing vertical land and water-based jumps, whilst wearing three breast support conditions. Underwater video cameras recorded the motion of the trunk and right breast. Trunk and relative breast kinematics were calculated as well as exercised induced breast pain scores. Key results showed that the swimsuit and sports bra were able to significantly reduce the superioinferior breast range of motion by 0.04 and 0.05 m, respectively, and peak velocity by 0.23 and 0.33 m/s, respectively, during land-based jumping when compared to the bare-breasted condition, but were ineffective at reducing breast kinematics during water-based jumping. Furthermore, the magnitude of the swimsuit superioinferior breast range of motion during water-based jumping was significantly greater than land-based jumping (0.13 m and 0.06 m), yet there were no significant differences in exercise induced breast pain, thus contradicting previously published relationships between these parameters on land. Furthermore, the addition of an external breast support garment was able to reduce breast kinematics on land but not in water, suggesting the swimsuit and sports bras were ineffective and improvements in swimwear breast support garments may help to reduce excessive breast motion during aqua aerobic jumping exercises.

Magnitude of multiplanar breast kinematics differs depending upon run distance

Recommendations for breast support, dynamic breast pain assessment, and implications for sports performance have been made within breast biomechanics research; however, these studies have been based upon short exercise protocols (2–5 min). The aim of this study was to investigate the effect of breast support on multiplanar breast kinematics over a 5-kilometre run. Ten female participants (34D or 32DD) conducted two 5-kilometre runs, in a low and high breast support. Relative multiplanar breast kinematics were averaged over five gait cycles at six intervals of a 5-kilometre run. Increases in multiplanar breast kinematics were reported from the start to the end of the run, with the greatest rate of increase in breast kinematics reported within the first two kilometres of running. The greatest relative increases in breast range of motion (34%), velocity (33%), and acceleration (41%) were reported in the superioinferior direction at the fifth kilometre (33 min of running) in the high breast support. Key findings suggest that the run distance, and therefore run duration, employed for both fundamental research and product validation protocols should be carefully considered and it is suggested that running protocols for assessing breast biomechanics should exceed 7 min.

The effect of breast support and breast pain on upper-extremity kinematics during running: implications for females with large breasts

The relationship between inappropriate breast support and upper-extremity kinematics for female runners is unclear. The purpose of this study was to investigate the effect of breast support and breast pain on upper-extremity kinematics during running. Eleven female recreational runners with larger breasts (UK D and E cup) completed a 7 min 20 s treadmill run (2.58 m · s−1) in a high and low breast support condition. Multi-planar breast and upper-extremity kinematic data were captured in each breast support condition by eight infrared cameras for 30 s towards the end of the run. Breast pain was rated at the end of each treadmill run using a numeric analogue scale. The high support bra reduced breast kinematics and decreased breast pain (P < 0.05). Upper-extremity kinematics did not differ between breast support conditions (P > 0.05), although some moderate positive correlations were found between thorax range of motion and breast kinematics (r = 0.54 to 0.73). Thorax and arm kinematics do not appear to be influenced by breast support level in female runners with large breasts. A high support bra that offers good multi-planar breast support is recommended for female runners with larger breasts to reduce breast pain.

The movement of the trunk and breast during front crawl and breaststroke swimming

Breast displacement has been investigated in various activities to inform bra design, with the goal of minimising movement; however, breast motion during swimming has yet to be considered. The aim was to investigate trunk and breast kinematics whilst wearing varying levels of breast support during two swimming strokes. Six larger-breasted females swam front crawl and breaststroke (in a swimming flume), in three breast support conditions while three video cameras recorded the motion of the trunk and right breast. Trunk and relative breast kinematics were calculated. Greater breast displacement occurred mediolaterally in the swimsuit condition (7.8, s = 1.5 cm) during front crawl and superioinferiorly in the bare-breasted condition (3.7, s = 1.6 cm) during breaststroke, with the sports bra significantly reducing breast displacements. During front crawl, the greatest trunk roll occurred in the sports bra condition (43.1, s = 8.3°) and during breaststroke greater trunk extension occurred in the swimsuit condition (55.4, s = 5.0°); however, no differences were found in trunk kinematics between the three breast support conditions. Results suggest that the swimsuit was ineffective as a means of additional support for larger-breasted women during swimming; incorporating design features of sports bras into swimsuits may improve the breast support provided.

Multiplanar breast kinematics during different exercise modalities

Multiplanar breast movement reduction is crucial to increasing physical activity participation amongst women. To date, research has focused on breast movement during running, but until breast movement is understood during different exercise modalities, the breast support requirements for specific activities are unknown. To understand breast support requirements during different exercise modalities, this study aimed to determine multiplanar breast kinematics during running, jumping and agility tasks. Sixteen 32D participants had markers attached to their right nipple and torso. Relative multiplanar breast displacement was calculated during bare-breasted treadmill running (10 kph), maximum countermovement jumping and an agility t-test. Exercise modality influenced the magnitude and direction of breast displacement, velocity and acceleration (p < .05). Jumping produced greater vertical breast displacement (.09 m) but less mediolateral breast displacement (.05 m) than running or the agility task, but agility tasks produced the highest multiplanar breast velocities and acceleration. Breast movement during jumping was predominantly in the vertical direction, whereas the agility task produced a greater percentage of mediolateral breast acceleration than running or jumping. Exercise modality impacted upon the magnitude and distribution of bare-breasted multiplanar breast kinematics in this homogenous 32D cohort. Therefore, to reduce breast movement in women of a 32D bra size, manufacturers may wish to design sport-specific products, with greater vertical support for exercise modalities incorporating jumping and greater mediolateral support for agility tasks.

Within-Participant Variance in Multiplanar Breast Kinematics During 5 km Treadmill Running

More and more studies are emerging reporting breast kinematics. These studies rarely present effect sizes, power, and variance in the data. Important inferences are drawn from these data, including applications to product design, breast pain assessment, sports performance effects, and more. The aim of the study was to explore the within-participant variance in breast kinematic data during a 5 km run. Multiplanar breast kinematics and within-participant variance, defined by the coefficient of variation, for 10 female participants wearing a low and high level breast support were calculated during a 5 km run. Greater within-participant variance was reported in the high level (mean=15%) breast support compared with the low level (mean=12%). Within-participant variance in breast kinematics did not change over the 5 km run. Differences in the magnitude of within-participant variance in breast kinematics were reported between directions of breast movement, with greater levels in the anteroposterior direction compared with mediolateral and vertical. It is important for the progression of this research area that the presence and sources of within-participant variance in breast kinematics are quantified and acknowledged, ensuring that the margin for meaningful differences can be reported.

The effect of different breast support conditions on multiplanar breast kinematics and kinetics during running

Outdoor fallers differ from indoor fallers substantially in demographics, lifestyle, health condition and physical function. Biomechanical predictors of outdoor falls have not been well characterized. Current validated measures of postural deficits, which describe only the overall postural behavior, are predictive of indoor falls but not outdoor falls. We hypothesized that a model-based description of postural muscle tone and reflexes, particularly during dual tasking, would predict outdoor falls. We tested whether postural stiffness and damping from an inverted pendulum model were predictive of future indoor and outdoor falls among older adults from the MOBILIZE Boston Study. The center of pressure data during standing were obtained from 717 participants aged 77.9 ± 5.3 years. Participants stood barefoot with eyes open for 30 s per trial, in two sets of five standing trials. One set included a serial subtractions task. Postural stiffness and damping values were determined from the postural sway data. After the postural measurements, falls were monitored prospectively using a monthly mail-in calendar over 6–36 months. Associations of postural measures with fall rates were determined using negative binomial regressions. After covariate adjustments, postural stiffness (p = 0.02–0.05) and damping (p = 0.007–0.1) were associated with lower outdoor falls risk, but not with indoor falls. Results were invariant by direction (anteroposterior versus mediolateral) or by condition (quiet standing versus dual task). Outdoor fall risk may be tied to postural control more so than indoor falls. Dual tasking is likely related to fall risk among older and sicker older adults, but not those relatively healthy.

Predictors of Three-Dimensional Breast Kinematics during Bare-Breasted Running

This study aimed to analyze differences in breast kinematics between breast cup sizes during running and the ability of breast and body size measurements to explain these differences. Forty-eight women (A to G cup; mean ± SD: age = 26.0 ± 6.0 yr, stature = 1.667 ± 0.064 m, mass = 62.78 ± 8.24 kg) with chest sizes of 32 to 38 inches participated. Chest and breast girths, a restricted anthropometric profile, suprasternal notch to nipple distances, and body mass index were measured, and breast mass was estimated. Multiplanar relative breast displacement, velocity, and acceleration during treadmill running were then recorded. Differences in breast kinematics were compared between cup sizes before and after allometric/polynomial scaling using significant breast and body size measures. All kinematic variables significantly increased with breast cup size (P < 0.05). Mean anterior-posterior (a/p), medial-lateral (m/l), and vertical bare-breasted displacements ranged from 0.030 to 0.059 m, from 0.018 to 0.062 m, and from 0.042 to 0.099 m, respectively, across A to G cups. Breast velocities ranged from 0.428 to 1.244 m·s(-1) (a/p), 0.411 to 1.708 m·s(-1)(m/l), and 0.819 to 2.174 m·s(-1) (vertical), respectively. Increases in breast acceleration varied from 11.664 to 48.438 m·s(-1) (a/p), 15.572 to 51.987 m·s(-1) (m/l), and 23.301 to 66.447 m·s(-1) (vertical), respectively. Scaling models found that breast mass was the only anthropometric measure to consistently explain differences in breast kinematics between cup sizes. Bare-breasted kinematics significantly increased with cup size during running. Differences in breast displacement, velocity, and acceleration between cup sizes could be predicted using estimates of breast mass based on conventional brassiere sizing. These data inform the design and evaluation of effective bra support.

Supported and unsupported breast displacement in three dimensions across treadmill activity levels

Appropriate sports bras are crucial to limit potential breast pain and ptosis. In an attempt to optimize breast support during exercise, manufacturers now produce activity level-specific sports bras. However, until breast movement across activity levels is understood, the criterion for such apparel is unknown. Therefore, the aim of this study was to quantify multi-planar breast displacement across treadmill activity levels and breast support conditions. Twenty-one D cup participants had markers attached to their nipples and trunk to calculate relative 3D breast displacement. Supported and unsupported mediolateral, anterioposterior, vertical, and resultant breast displacement was assessed during treadmill walking up to maximum running. Unsupported resultant breast displacement increased from 4.2 ± 1.0 cm during walking to 15.2 ± 4.2 cm during running. There was no change in breast displacement amplitude or direction as running speed increased above 10 km · h−1, with vertical breast displacement then accounting for ∼50% of overall displacement. While breast support was effective in reducing the amplitude of breast displacement during walking and running, the direction was unaffected. In conclusion, instead of activity level-specific breast support, future research should identify multi-planar breast kinematics during various sporting modalities. This might lead to production of a sports-specific bra to reduce the negative consequences of breast movement.

Three-Dimensional Kinematics of the Breast during a Two-Step Star Jump

Anecdotal reports suggest two-step star jumps cause excessive breast movement and discomfort, leading to recommendations for this activity as a diagnostic tool to determine effective breast support in a retail environment. The aim was to investigate multiplanar bare-breast kinematics during the two-step star jump and to establish the relationship between breast kinematics, discomfort and cup size. Thirty-nine females completed five two-step star jumps with no breast support after which breast discomfort was rated. To establish relative breast kinematics infrared cameras tracked the 3D co-ordinates of breast and body markers. Maximum resultant breast displacement, velocity and acceleration during jumping reached 18.7 cm, 93.1 cm·s⁻¹ and 3.6 g, respectively. Significantly more vertical breast displacement (p < 0.01) and velocity (p < 0.01) occurred compared with mediolateral and anteroposterior kinematics. Breast discomfort increased as cup size increased (r = .61). Two-step star jumping stimulated multiplanar breast kinematics and high levels of breast discomfort. Therefore, this activity may be useful in a retail outlet to determine the function and comfort of a sports bra.

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

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 · 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.

Effects of high and low breast support on breast kinematics and kinetics during treadmill running

Results: The mean vertical component of the peak bra/breast spring force during treadmill running was greatest during the downward breast trajectory and was approximately 30% less in the high breast support condition (13 N ± 7 N) compared to the low support condition (17 N ± 10 N). This force reduction was accompanied by a 300% decrease in breast and bra discomfort. Conclusion: Wearing a well-fitted supportive sports bra is recommended for females with large breasts to reduce the breast forces and, in tum, exercise induced breast and bra discomfort during physical activity such as treadmill running.