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How to start a fitness clothing line

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How to start a fitness clothing line

An introduction into the industry


If you’ve been served any activewear ad on Instagram, or better yet, seen an influencer tout an activewear line, you know that sportswear is no longer an exclusive genre of fashion reserved for the likes of Nike, Adidas and Under Armour.

In fact, while Gartner’s 2018 study on the Activewear Index showed that the three giants make up a third of overall traffic for activewear, startups and medium-sized activewear outlets are making their way to center stage – and plan to stay there for a long time.

Indubitably, activewear is an infinitely bigger industry than the new-year-new-me trend. Carefully mapping out your activewear manufacturing is more important than figuring out how you’re going to take it to market. Why?
You can create all the hype and aesthetic, but people buy with their hearts and justify it with their heads. As a result, if you bring to market a sub-par product, don’t be surprised to see your brand plummet faster than a stunt performer at a Red Bull event.

So, if you’re in the market to know how to start a fitness clothing line – be it workout clothes and gym wear, athleisure garments, athletic clothing etc. here’s exactly what you need to consider about the manufacturing of your pieces before diving headfirst (with the parachute).

Define your activewear category

With all the glitter and fairy dust lining this exciting market, don’t forget to first carve out your niche. Begin brainstorming and researching, where you want to plug your activewear line into is crucial. Athleisure? High-performing techwear? Yoga? Or something totally new altogether.

Whichever way you want to identify your brand, build your brand’s DNA and make sure you’ve got all the supporting documents that allow you to design your pieces. For example, if you’re after designing a line focused on performance-wear, you need to have the right approvals and certifications to classify your designs as such.

Activewear styles largely fall into three buckets:

High Impact: Performance-focused activewear with maximum support, flexibility, and of course, comfort.

Medium Impact: Most athleisure brands fall into this category with medium-impact apparel having an average level of support and performance-based capabilities for activities such as weight lifting, boxing and cycling.

Low Impact: Also classified as athleisure, low impact styles offer little support and best suited for activities like yoga, hiking, Pilates and casual exercise and even the walk-to-brunch on a Sunday look.


Be clear on design and construction elements that define your product

In many ways, once you have identified your market, the finer details you add your designs and the amount of attention to detail you pay to your garments, will help to make the final product glow in the market.

They will define your market penetration and customer satisfaction from a product standpoint. A few basic considerations in this regard would be:

  • Fabrication
  • The fit
  • Support
  • Paneling
  • Fabric weight (GSM)
  • Reflective details
  • Ventilation
  • Stitching



Consider the type of activity you are designing for and choose fabrics wisely. Typically, moisture-wicking fabrics are a choice selection to minimize odors and keep the wearer feeling fresh.


How much compression your pieces offer matters. Compression offers a variety of benefits such as reduced muscle fatigue, strain prevention, increased power and movement.


Although primarily governed by the type of material you use, consider how much support your activewear pieces will provide. The level of support coincides with the type of activity you associate your pieces with.

Designing for high impact activity like running, court and field sports? High support and anti-bounce sports bras are key.

Consider materials such as Mobilon (a transparent elastic tape) used inside bindings near cutouts, armholes and necklines to provide protection for stitches and avoid them coming apart when stretched. It is also used to ensure body hugging fit and maintain supple qualities of the garment.

On the other hand, Power Mesh is used to reduce stretch quality and provide better structural integrity. It is sandwiched in between the fabric layers.



Panels in sportswear are specific section of a piece of clothing targeting key muscle groups you’d expect to be exercise. For example, running shorts have paneling in line with your quadriceps (thighs) as they are your activated muscles during a run. These panels typically have specific fabrication and design elements geared to offer the best support.

Fabric weight (GSM)

Fabric weights depend on the season you’re designing a collection for s well as the type of activity. Sport lines designed for summer have lighter weights whilst colder seasons demand a heavier weight.

Similarly, high-level activities such as running call for lighter fabrics. A fine balance of the GSM of your fabric also affects the wearability, so consider carefully.

By the same token, fabric weights should also consider body temperature and climate and environmental conditions. For warmer climates, consider cooling fabrics and for cooler climates, vice versa.

Reflective details

Reflexive details aren’t a second thought. As with most of our advice, consider the activity and whether your clothing would benefit from light-reflective stitching and prints.

A night-time cyclist or runner would benefit from bonded stitching. For tops, these reflective details are often found along the arms and the back whilst for shorts and leggings, they’re added to the sides of the shins.


Ventilation plays a big role in blood circulation. Design elements such as cut-outs, mesh paneling, and laser-cut details are found strategically placed by high sweat areas.



The type of stitching on a garment matters and it’s to not only to hold the garment together but to also offer the most comfort and avoid irritation to the wearer.

Flatlock stitches are typically reserved for compression attire to avoid irritation and discomfort whilst overlock stitching is found on base-layers, tees in knit fabrics to help with stretch and recovery.

Stitching techniques such as the bag out style creates stitching that is invisible from both the inside and outside. These types of stitching techniques leave a clean finish. Bonding is another technique used to achieve this.

No matter what type of activewear you design, make sure that the seams can withhold being stretched. Nothing is worse than seeing your activewear double in size (with no come back) after an hour long workout.


Understand your fabrics

If you are new to the fashion and athletic wear industry, here are some quick tips to help you understand the basics of fabrics

For close to skin garments such as leggings and sports bras, opt for a poly-spandex mix (also known as interlock) and/or power mesh. Poly-spandex mix has a high gauge, providing beneficial give, stretch and fit. Poly-spandex mixed fabrics also have a high recovery quality and have no show-through (i.e. it passes the squat test). Power mesh fabrics are ideal for sweat-zones as they provide ventilation and aesthetic appeal. Power mesh also offers good stretch and fabric recovery.


For loosely fitted clothing, opt for single jersey polyester, stretchy nylon and woven fabrics. These fabrics are light-weight and drape well.


Create a collection to represent your ideas

How many garments should you have per collection? What types of garments should you include? These are all decisions you need to make by assessing your resources. Few things you always need to keep in mind include

  • A collection is usually made up of 8-15 garments of varying styles, designs and purpose but is united by common elements.
  • Opt for a broad range of garments such as sports bras, leggings, shorts, t-shirts and capris so you appeal to a wider demographic
  • Puffer and bomber jackets (and other outerwear) are slowly creeping into collections across global and local brands as they offer extra aesthetic and trend
  • Athleisure is a very trendy market, consider appealing to those looking for this style
  • Do your due diligence and research well-established and loved silhouettes, colors, seasonality trends and other factors that influence a purchase. How tip: Browse the comments and review sections of your potential competitors to get an idea of what your target market wants.
  • Appropriate fabrication is non-negotiable. Getting it wrong spells disaster.


Choose the right activewear manufacturer

There is an infinite number of activewear manufacturers on the market – some with more experience than others. After you do your research and are comfortable to approach a few sportswear manufacturers with your ideas, make sure they are ready to execute it for you.

Here are some tips to help you identify an established manufacturer:

  • Ensure that the activewear manufacturers you speak to have experience – and not just any experience but experience and specialization in activewear. This will allow them to provide valuable input to your fabric selection, design and provide recommendations where they see fit.
  • Sportswear manufacturers require dedicated machinery. At its core, woven garments are produced by weaving two sets of yarn whilst knit garments are produced by interloping one set of yarn. Woven and knit fabrics behave differently and thus require specialized machines.
  • Have a clear understanding of lead times, ability to source material, their network of suppliers and brands they’ve worked with (if they are able to provide that), level of customer support and their requirements around minimum order quantities (MOQs). Consider how sustainable they are as a custom activewear manufacturer, as well.
  • When analyzing samples, do a quality assurance (QA) check. Check the seams (stitches) whether they are even, have unnecessary give, etc.
  • Do wash tests to see if your colors fade or spill and ask your athletic clothing manufacturers to conduct stretch and recovery tests at proper labs for you to further assess.
  • Be across wash cycles and care information of your materials.


There are many factors that go into the manufacturing of your sportswear. Therefore spending as much time as required among your narrowed down list of fitness or gym clothing manufacturers to pick the partner that fits you and your activewear brand is crucial.

Runway Kit offers low MOQ production capacity coupled with decades of experience in the activewear industry to bring you a sustainable and digital platform to start your activewear line.

Partnering with powerhouses that manufacture the world’s leading sportswear brands, get in touch with the experts at Runway Kit to produce your dream label.


Runway Kit offers fashion designers and entrepreneurs the option to design, sample and manufacture in smaller, flexible quantities – all at start-up friendly, transparent costs.

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