sports bras 1 The Construction of Sports Bras

Sports bras are a different breed of clothing. Their fabric and construction are completely unique and their expected level of performance is like no other clothing. They’re expected to keep our girls in place so that they don’t bother or bounce around during our workouts yet they’re suppose to be breathable, flexible, and comfortable. To be honest, I don’t think I could or will ever make a sports bra. This past year, I visited factories and saw first-hand the machines that created this category of clothing and never ever would I want such machine in my apartment. They’re loud, huge, and kind of scary looking. I’m not saying they can’t be made my home sewers, because they can (click here to see how Melissa of Fehr Trade made her own running vest and leggings), I’m saying I hesitate to dive into the category. Regardless, I think the technology is really cool and interesting to know and I wanted to share my knowledge of the category with you. Enjoy my loves…

Fabric: The fabric of sports bras and all other active wear is what sets this category of clothing apart from every day wear. I’m sorry if my next bit gets a tad bit technical but the technology is quite amazing and I promise that if you follow along and read slowly, it will all make sense.

As opposed to the fabric of every day wear (cotton, wool, linen), the fabric of active wear has one main purpose – to move moisture from the skin, through the fabric, and to the outside air (this process is called wicking) in order to cool down the wearer. What’s interesting about this is that most active wear, including sports bras, are made of polyester, nylon, lycra, or spandex or a blend of the previous four with cotton yet polyester, nylon, lycra, and spandex (not cotton) are hydrophobic by nature, meaning they don’t absorb water easily. So how can a hydrophobic fabric move moisture away from the body? Well, by modifying the composition and structure of the fiber while it is being manufactured (because polyester, nylon, lycra, and spandex are manufactured fibers/fabrics), they are able to transport the moisture from the wearer’s body to the outside air, and thus, keep the wearer cool during workouts.

So how does the fiber or fabric change during manufacturing that allows it to wick? I’m so glad you asked. Moisture is moved from the wearer to the outside air through the tiny spaces between the fibers. The teeny tiny spaces form just as small passageways, called capillaries, that move moisture away from the body. The narrower the capillaries, the more effective the transportation of moisture. So, the fabrics of sports bras and all other active wear have been modified to have more and narrower capillaries. Simple, right?

Today, the best fabric for wicking is a called COOLMAX. It is trademarked by INVISTA and you will know that a sports bra or another piece of active wear is made of this fabric because the content label will actually state the trademark name COOLMAX (as opposed to just saying polyester, nylon, lycra, or spandex). The next best fabric for wicking is another trademarked fabric called SUPPLEX. It’s not as good as COOLMAX but is still does a damn good job wicking.

Cotton is also used in sports bras but is almost always used as a blend with nylon, polyester, lycra, or spandex. Cotton, by nature, is a hydrophilic fiber, meaning it attracts water but it also retains water. For everyday wear, this is okay, but for active wear, this is not okay. The wearers wants to get rid of the moisture he or she is sweating, not retain it. Cotton is also used in blends to provide a softer hand.

Mesh is also used in active wear for breathability. I have noticed that many of my sports bras are lined with mesh and the middle section of the racer back as well as the cleavage area have mesh to allow air to pass through.

sports bras diagram1 The Construction of Sports Bras

Construction: Sports bras are almost always and pretty much solely sewn with coverstitches and chainstitches. As with normal bras, a straight stitch cannot be used to sew sports bras because it would break as we moved vigorously, and many times wildly, throughout working out. Although zigzag stitches provide give to a seam, it still isn’t enough to withstand a workout.

The seams of sports bras are also almost always and pretty much solely overlapping (as opposed to placing right sides together and sewing) and many times coverstitches straddle the seam (see sketch). The reason for this type of seam construction is used to reduce bulk.

Silhouette: There are types of silhouettes of sports bras – compression, encapsulated, and underwire.

Compression, just like its name, compresses the chest to provide support and keep the girls in place. These bras usually don’t have seams, the only exception being a side seam, and is best for the smaller busted girls (A-cup and maybe B-cup).

The second type of silhouette, the encapsulated, provides more support than the compression with the use of seams that shape larger busts (B-cup and bigger). Although the seams can be a princess seam shape, they are usually in the shape of a bra cup. Also, binding is top applied on the inside and straddles the cup seam. The purpose of the binding is to act as an underwire but with less rigidity.

The third type of silhouette, the underwire, is for the largest of girls (C-cup and larger ((although B-cups can wear them if they want more support)) ). This type of bra is basically a normal bra but made with activewear fabric.

All three silhouettes of sports bras can be made as a racer back or with two straps (one left and one right). The racer back provides the most support.

Band: Just as with normal bras, the wider the band, the more support provided.

Closure: Sports bras usually have no closure and are a pull-on type of clothing. The reason is closures can be very irritating during a work out (hooks and eyes = ouch!). If sports bras have a closure, it is usually in the form of a hook and eye and it is in the back of the bra, not the front.

When to throw away: Just as a rule of thumb, if you wear your sport bra 3-4 times a week, it should be thrown away/replaced every six months. The reason for this is the elastic looses elasticity and retention and doesn’t provide support is used to.