Why support matters for runners
We love running, we believe everyone should run. But there is no denying that running is a high-impact, repetitive activity. Without adequate support, breast tissue moves in multiple directions with each stride, which can become uncomfortable and distracting. In a large survey at the London Marathon, about one in three women reported breast pain. Broader surveys of exercising women have reported rates as high as roughly 70%, depending on age and activity. (PubMed, IASP)
Purpose-designed sports bras are a game changer. Encapsulation and hybrid designs can halve breast displacement during running compared with no sports bra, compression designs also helping at smaller cup sizes or lower intensities.
Several controlled studies now show movement reductions of roughly 50–60% at running speeds around 10 km/h, which is a significant difference you can feel. (Nature, SAGE Journals)
Support does more than tame bounce. There is emerging evidence that support level can influence trunk and lower-limb mechanics as well as increase performance, which is another reason to focus on adequate, comfortable support rather than simply “as tight as possible.” (PMC)
The benefits of a proper running bra
- Less pain and more comfort. Reduced movement means less strain on skin and supporting structures, fewer hot spots and less distraction on the run. (PubMed)
- Better motion control. Lower vertical and multi-planar movement improves comfort during easy miles and hard sessions alike. (Nature)
- Better Performance. A study conducted by Portsmouth University found that wearing a bad sports bra can result in a 4cm reduction in stride length, meaning you would run an extra mile over the course of a marathon distance! (UoP)
- Confidence and consistency. When kit feels right, it is easier to keep up training. At the elite end, professional fitting programmes have reported notable comfort gains and perceived performance benefits.
Bra types explained
- Compression – Uses uniform pressure to hold both breasts close to the body. Often lighter and simple. Best for smaller cups or lower impact training.
- Encapsulation – Separate cups support each breast individually, improving control across directions. Often preferred for C+ cups and high-impact running.
- Hybrid – Combines both approaches for a balanced feel.
In controlled testing, encapsulation typically reduces displacement more than pure compression at running speeds, although the best choice still depends on cup size, activity and fit. (Nature)
Hero brands to start with: explore Maaree for stabilising over-band concepts and adjustability, and Shock Absorber for proven high-impact designs. We keep ranges fresh, so check current availability.
How to choose the right support
1) Match support to your session and size
Use this simple guide as a starting point, then fine-tune through fit:
- AA–B cup: easy runs and gym work often suit compression or light hybrid; for intervals or long runs, step up to hybrid or encapsulation.
- C–DD cup: hybrid or encapsulation for most runs; look for firm underbands and adjustable straps.
- E+ cup: prioritise encapsulation or hybrid designs with multi-row hooks, robust cup construction and stable strap geometry.
2) Run-ready fit checklist
- Underband: snug on the loosest hook. It should sit level around the body, with space for two fingers under the band.
- Cups: breast tissue fills the cup without wrinkling or spillage. Encapsulation styles should sit flat at the centre front.
- Straps: adjust to remove slack, but avoid digging. Convertible or cross-back options can boost stability.
- Jump test: jog on the spot. You should feel contained, supported and able to breathe comfortably.
Design choices matter. In a University of Portsmouth analysis of 98 sports bras, five characteristics explained about 37% of movement-reduction performance: encapsulation style, padded cups, nylon content, an adjustable underband, and a higher neck drop. That is strong evidence to prioritise features and fit over brand hype.
3) Underwire vs wire-free
Underwire can improve shape and separation in encapsulation styles, while modern wire-free designs can feel softer. Both can work well for running when the fit is dialled in. Try both if you are unsure.
4) Fabric and construction
Look for moisture-wicking, quick-dry materials, flat or bonded seams at high-friction zones, and wide straps that spread load. These details reduce chafing on long runs.
Need a hand? Book a Free Sports Bra Fitting. Our team are extensively trained and will help you pick a support level and fit that suits your size, pace and training.
Care, lifespan and when to replace
Rotate two or more bras if you run often. Wash cool, avoid fabric softener, and line dry to preserve elasticity. Replace when the band stretches, straps slip even when tightened, cups crease, or when you notice more bounce on runs. Heavy weekly mileage will shorten the lifespan.
Common myths, busted
- “The tightest bra is always best.” Not true. Over-restrictive designs can change how your core moves and may increase spinal loading in modelling studies. Balance support with comfort and breathing. (PubMed)
- “Your sports-bra size is the same as your everyday bra.” Sizes vary by brand and style. Use the fit checklist and a jump test to validate.
- “Compression is only for small cups.” Well-designed compression or hybrid styles can work across sizes for the right session. Evidence still favours encapsulation for higher impact or fuller cups. (Nature)
A quick note on the “maximum support” trend
A recent computer-simulation study from the University of Portsmouth modelled different support conditions in a runner and suggested that extreme attempts to eliminate all breast motion could increase estimated loading within the spine.
This is early work with a very small sample, so it guides common sense rather than setting strict rules. The practical takeaway is still simple: aim for adequate support that feels natural to breathe and move in. (PubMed)
Brand spotlights
- Maaree – Known for designs that stabilise breast motion and offer smart adjustability to fine-tune support. Explore Maaree sports bras.
- Shock Absorber – A UK staple for high-impact running support, with decades of testing behind the range. Explore Shock Absorber sports bras.
Browse our full Sports Bras & Underwear selection or pop into Alexandra Sports to try options in person.
Related services
Comfort up top and stability underfoot make a strong pairing. If you are refining your whole running setup, our a Gait Analysis to determine your best footwear options alongside a fitted sports bra will put you in the best possible position for comfortable, injury-free running.
FAQ
References and further reading
- University of Portsmouth Research Group in Breast Health overview. (University of Portsmouth)
- Displacement reduction during running: compression and encapsulation examples. (Nature)
- Well-fitting sports bras reducing vertical displacement by about 60% in testing. (SAGE Journals)
- Prevalence of exercise-related breast pain in runners and active women. (PubMed)
- Design features that explain support performance across 98 sports bras.
- Associations between support level and trunk or lower-limb mechanics. (PMC)
- Early modelling work on very high support and potential spinal loading. (PubMed)
- Real-world elite fitting programmes and perceived performance benefits. (The Guardian)