---
source_url: "https://www.forbes.com/sites/brucelee/2026/02/02/how-to-choose-the-right-sports-bra-study-shows-effects-on-breathing/?utm_source=openai"
title: How To Choose The Right Sports Bra. Study Shows Effects On Breathing
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> **Original source:** https://www.forbes.com/sites/brucelee/2026/02/02/how-to-choose-the-right-sports-bra-study-shows-effects-on-breathing/?utm_source=openai

![Sports bra](https://imageio.forbes.com/specials-images/imageserve/6980ce69c58fc2792e43ebdb/Sports-bra/0x0.jpg?width=960)

A recent study found that sports bras selected by female runners impaired their breathing when they were running on treadmills. (Photo: Getty)

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A sports bra can literally take your breath away—if it’s too tight. Not too tight in a too-cool or too-excellent way but too tight in a squeeze-your-chest-too-much way. That’s what a running study [published](https://journals.lww.com/acsm-msse/abstract/9900/sports_bra_restriction_on_respiratory_mechanics.466.aspx "https://journals.lww.com/acsm-msse/abstract/9900/sports_bra_restriction_on_respiratory_mechanics.466.aspx") in the journal _Medicine & Science in Sports & Exercise_ found.

## Tighter Sports Bras Led To Harder, Faster and Shallower Breathing

That study ran with the question of whether sports bras could be so tight that they could make it harder to breathe and impede a runner’s respiratory function. It also included nine female runners — experienced and highly trained ones who had competed in 800-meter to marathon events at the national and international level. The study participants ran on a treadmill at various speeds while wearing different types of sports bras, including those they had selected. Shalaya Kipp, Michael G. Leahy and A. William Sheel from the School of Kinesiology at the University of British Columbia conducted the whole thing.

The results were breathtaking, to say the least. Even when wearing sports bras they had selected for fit, the runners had to work significantly harder to breathe, measured at an average of 350 Joules per minute. Switching to sports bras with looser underbands did result in their work of breathing going down to 301 Joules per minute. The participants’ self-selected sports bras were also associated with faster (an average of 57 versus 52 breaths per minute) and shallower (an average of 1.97 liters per breath versus 2.05) breathing than the sports bras with looser underbands.

Such results provided further evidence that many women are not choosing sports bras that fit properly. When it comes to the percentage of women who may be wearing the wrong-sized sports bra, 80% to 90% are a pair of numbers frequently tossed around the internet. For example, the following tweet (or X) mentioned 80%:

MORE FOR YOU

Meanwhile, [the Adidas website says](https://www.adidas.com/us/blog/444197-how-should-a-sports-bra-fit "https://www.adidas.com/us/blog/444197-how-should-a-sports-bra-fit"), “Studies have found that 90% of women aren't wearing their correct bra size.”

## The Type Of Activity Determines The Sports Bra Needed

There are two considerations when it comes to choosing a sports bra size. One is that anything that’s too tight around your chest can be uncomfortable and restrict movement. It can also compress different structures like nerves and block the flow of blood or lymph, [as I have described previously in _Forbes_.](https://www.forbes.com/sites/brucelee/2023/03/11/wearing-sports-bras-too-long-led-to-this-tiktokers-breast-health-scare/ "https://www.forbes.com/sites/brucelee/2023/03/11/wearing-sports-bras-too-long-led-to-this-tiktokers-breast-health-scare/") The other consideration is that anything too loose may allow your boobs to bounce around too much, resulting in pain and discomfort.

The proper balance depends on the type of activity you will be engaging in while wearing the sports bra. The most support with wider straps is needed for vigorous high-impact activities such as running, mountain biking, mountain hiking or other high-intensity workouts. Medium-impact activities like road cycling, skiing and flatter-ground hiking call for more medium support. Low-impact activities like walking, yoga and strength training may only need low support with narrower straps.

Breast size matters, too. D cups or larger can call for high support in all activities. A or B cups may need only low support for all activities.

## Determine The Sports Bra Size You Need

When measuring bust size, don't wear a padded bra. (Photo: Getty)

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Speaking of size, it’s a good idea to be up to date on your bra size measurements in general. Since the size and configuration of your breasts and chest can change over time, [as I have detailed before in _Forbes_](https://www.forbes.com/sites/brucelee/2023/08/15/tiktokers-claim-bee-pollen-makes-your-breasts-larger-but-does-it-really/ "https://www.forbes.com/sites/brucelee/2023/08/15/tiktokers-claim-bee-pollen-makes-your-breasts-larger-but-does-it-really/"), bra size is one of those things to re-check regularly. It’s one thing to still wear outdated fashion like extremely distressed denim or tall Ugg boots. But it’s another thing to stick with an outdated bra size.

Although a sports bra may fit a bit snugger than your standard bra, you should sport the same size for each. To figure out this size, first wrap a tape measure around your chest just below your bust to measure the size of your rib cage, rounded down to the closest inch. Your rib cage measurement then corresponds to the right band size for you: a 25 to 27 inch rib cage to a band size of 30; a 27 to 29 inch to a 32; a 29 to 31 inch to a 34; a 31 to 33 inch to 36; a 33 to 35 inch to 38; a 35 to 37 inch to 40; a 37 to 39 inch to 42; and a 39 to 41 inch to 44.

The next thing to do is go bust, so to speak. Wrap the tape measure around your chest where the fullest part of your breast is located. The measurement rounded to the nearest whole number is your bust size.

Your cup size then is then based on your bust size minus your rib cage measurement. A three inch difference means a AA cup size. It’s then as easy as ABC to figure out the relationship between this difference and larger cup sizes. Each added inch means stepping up to the next letter in the alphabet, progressing from an A size (which would correspond to a difference of 4 inches) to a B (5 inches) to a C (6 inches) to a D (7 inches) size. The next step up does a double take at the D-level for a DD size (8 inches) before proceeding to an E (9 inches) and F (10 inches).

### Check The Fit Of The Sports Bra

Once you’ve got the right cup size, you still want to make sure everything fits. That means that your breasts should be fully contained and centered within the cups. This shouldn’t be a cup runneth over situation. This shouldn’t be a cup partially full situation either. A sign that the cup may be too big for you is the fabric dimpling up or wrinkling rather than sitting smoothly on your breasts.

You’ve got to play with the band, too, so to speak. The band should fit snuggly around your rib cage rather than around your breasts themselves. In order to make sure that the band is not too tight, give it the finger — or rather two of your fingers. Make sure that you can fit exactly two fingers and no more between the band and your body.

Next, like Taio Cruz sings in that song “Dynamite,” throw your hands up in the air so that they are above your head and look at yourself sideways in a mirror. If the sports bra band looks higher in the back than it does in the front or your breasts slip out below the band, you may want to say “Ayo, gotta let go” of this band size and opt for a tighter one.

Make sure that you are not so strapped for time that you don’t pay close attention to the straps as well. Straps that take a dig at you literally — meaning digging into your skin — are too tight. Don’t play things too loose either with the straps falling off your shoulders. This two-finger test should apply to the shoulder straps as well. A sports bra with adjustable straps gives you more customizability. Wider straps typically offer more support than thinner straps but may be harder to keep hidden.

Then, jump around. Jump up, jump up and get down. Try various vigorous movements to see with every move you make how much your breasts move versus remain secure and supported. At the same time, see what happens with every breath you take. You should be watching not only breasts but the other parts of your body, too. Choosing a sports bra that fits more properly than your previous ones could end up being quite a breath of fresh air.