Breasts: Getting the right support

What is appropriate breast support?

Breast movement and breast strain 

  • Breasts move relative to the chest wall when women participate in physical activity. 
  • Breast motion is exacerbated during activities where the torso moves up and down (jumping and running). 
  • Excessive breast motion = exercise-induced breast pain = negatively affects occupational performance. 
  • Wearing appropriate external breast support (such as a sports bra) typically recommended. 
  • Breast injuries and pain still common, despite extensive biomechanical research over the past 15 years to improve sports bra designs = more research needed. 

Breast tissue is not like other tissues in the human body - it doesn’t have any muscle or bone within it. 


The complexity of breast motion can be seen in this video. It is taken from a 34DD (UK size) woman running on a treadmill whilst bare-breasted, so not wearing any external breast support. And you can see here, the breast doesn’t just move up and down, it moves in all directions and even deforms and is manipulated by the movement it is going through. There is an array of markers on the breast to try and track this motion.

There is a time-lag that occurs between the body and the breast, the body moves upwards followed by the breast. The breast then reaches its highest point just as the body starts to move downwards, which then pulls the breast downwards which creates a real strain on that breast tissue. And that is essentially what sports bras are trying to limit, that time-lag, to make the movement of the breast more in sync with the movement of the body. 

Bra types available 

There are three basic types of sports bra – compression, encapsulation and combination. 

They each support the breasts in a different way: 

compression bra

Compression sports bra (or crop top)

  • A compression sports bra, also known as a crop top style, aims to compress the breasts closer to the chest in order to reduce breast movement. 
  • Moves the centre of mass of the breasts closer to the body, which reduces what we call in biomechanics, the moment (force x distance) of the breast. 
  • Usually one piece of strong, elastic material 
  • Stretches when putting on and taking off – decreases lifespan of bra 
  • Research promotes use of this style for smaller-breasted (<D cup) women only 
encaptulation bra

Encapsulation sports bra 

  • An encapsulation style sports bra separates and supports each breast individually halving the mass. 
  • They are more of a sturdy construction and many tend to use underwire to create that separation to form two individual cups. 
  • Research promotes use of this style for larger-breasted (>D cup) women to reduce movement and discomfort. 
combination bra

Combination sports bra 

  • There are bras on the market that incorporate both an encapsulation and a compression element. There tends to be encapsulating cups but with an external layer of fabric spanning across them to create compression. 
  • Can reduce exercise-induced breast pain by minimising ‘breast slap’ - simultaneously elevating and compressing the breasts. 

It is not clear which sports bra style is best, although it seems that different sports bra styles suit different functions and breast sizes, therefore having a variety of styles on the market is useful. 

Considerations for work 

Wearing body armour causes a level of discomfort for female officers and a restriction in the capability to perform actions, especially running and self-defence, which are the most physical activities performed. Wearing an appropriate bra may be critical for comfort when worn with body armour. 

Research has shown that 71% of female police officers are wearing an underwired everyday bra, with the next most common bra being a sports bra (17%). However, research showed that when officers were fitted for a new sports bra and underwired bra to wear for duty, over 70% of officers stated that they found the sports bra was more comfortable. In addition, wearing a sports bra meant that various actions were easier to perform, and they would most likely wear a sports bra in future under their body armour. 

Washing and wearing of sports bras 

So how often should you change your sports bra? What is the lifespan of a sports bra? A lot of that comes down to the washing and wearing of the garment as laundering affects the mechanical properties of some sports bra materials. After 25 washes of a sports bra the support it provides will start to reduce, although it is likely to remain comfortable. As a rule of thumb, when you change your trainers you should consider changing your sports bra! 

Bra sizes and getting a good fit 

Bra sizing systems 

Berlei Australia conducted a survey to study women’s figures were chest circumference, bust and rib cage (underbust) measurements were used to identify bra size in the 1920s. 

Cup sizes were introduced in 1928 - known as ‘Alphabet bras’, you could buy an A cup (youthful), B cup (average), C cup (large) or D cup (heavy). 

Imperial (inches) and metric (cm) bra sizing systems are used by manufacturers and retailers around the world today which are based on using a tape measure to assess bra size. 

Limited progress has been made to develop a more accurate and scientific sizing system since then! 

What are the issues with the bra sizing systems? 

  • Bra size is difficult to measure – affected by breathing and posture. 
  • Measuring should take place over a well-fitted, unpadded, thin bra – so measurements are not meaningful if your own bra does not fit.
  • Crop tops often vaguely sized as small/medium/large. 
  • The sizing of most bras are derived from directly measuring only one or two women deemed as “fit models”. 
  • Simple chest measurements do not adequately represent the 3D shape of female breasts. 

Bra fit - why do women get it wrong? 

Poor bra fit is very common - approximately 87% of female police officers are reported to be wearing ill-fitting bras - but why? 

  • A lack of knowledge regarding the need for appropriate breast support during physical activity / in the workplace and how a bra should fit. 
  • Inconsistencies between manufacturers, companies use their own size charts and grading methods. 
  • Inadequate bra designs. 

Research that has evaluated the traditional method of bra sizing (using a tape measure), compared with using a set of bra fit criteria, has confirmed that the traditional method overestimates band size, underestimates cup size and becomes less accurate as band size increases. 

Negative health effects of poor bra fit 

A correctly fitting and supportive bra is essential to good health at work. 

A poorly fitting bra can lead to: 

  • breast pain 
  • poor breast support 
  • poor posture 
  • upper body musculoskeletal problems (e.g. neck pain, back pain, shoulder pain) 
  • deep bra furrows in the shoulders (due to excessive pressure from shoulder straps that are taking too much of the weight of the breasts) 

The incidence of bra fit issues were investigated within a population of British Army recruits during their Basic Training. 75% of recruits reported at least one bra fit issue. Nearly half of recruits reported their bra straps “sometimes”, “often” or “always” dug in. 

This research highlights that for women who require high breast support for their job, having a correct bra fit and the most appropriate bra for their activity, is so important! 

How to assess your own bra fit 

Research suggests that you should follow a set of best-fit criteria, rather than use a tape measure, when you are choosing a bra (everyday or sports type). The recommendation is that you should educate yourself on how to assess your own bra fit, so you can continually be evaluating your bras. This knowledge empowers you to take control and not have to rely on others. 

Previous research has shown that 77-87% of female police officers were wearing underwired bras or sports bras in an incorrect size (generally wearing cup sizes that were too small), highlighting that, as in the general population, it is important to check your bra fit regularly. 

How does your bra fit?

Follow these tips to get the perfect bra fit and the maximum support and comfort for your breasts.
The band should fit firmly around the chest (firm = no more than 5 cm give,or 2 fingers). 80% of the support provided to the breasts should come from the band, and it should fit so that it is comfortable to expand and contract when breathing hard.  The band should also be level all around the body and not ride up at the back.
The breasts should be encased within the cups, with no bulging or gaping. 
The underwire should follow the natural crease of the breast and not rest on any breast tissue, particularly under the arm.
If an encapsulation sports bra is being worn then the front of the bra should sit flat against the body.
The shoulder straps should not be too tight, or too loose - no more than a 5 cm give (2 fingers). Only 20% of the support provided to the breasts should be provided by the shoulder straps.
When trying on a sports bra, jump up and down in the changing room if possible, as this will place the most demand on the sports bra to ascertain whether the support level is correct for what you need.

Understanding breasts, the challenges and concerns