As someone who likely takes your health and fitness very seriously and takes great care in conditioning your body, you’ll want to exercise (pun definitely intended) the same amount of care with the clothing and equipment that helps you to reach those goals. Workout clothes have different materials and functions that your everyday clothes, so precautions need to be taken when caring for them.
For example, they are going to accumulate a lot more sweat than, say, your office clothes. This extra moisture means that it is imperative to air your gym clothes out between uses to avoid mold and mildew accumulation in your gym bag.
When you wash your gym gear, you should do so in a way that will minimize damage to the elasticity and sweat-wicking abilities of the spandex or polyester. This means, first and foremost, washing all of your workout gear together. Just like separating out delicate and dark fabrics in your regular laundry, you should do a separate load for your gym clothes. This is not only because they should ALL be washed in cold water (warm or hot will damage the elastic), but also because things like zippers, Velcro, and even towels and other cottony fabrics will scratch, snag and stretch out the synthetic, functional materials in your workout clothes.
Also unlike your other laundry, you should forego the fabric softener and reduce the amount of detergent you use when washing workout gear. This is because both of these can cling to the garments and create a seal, which traps in sweat and odors and diminishes the sweat-wicking functions of these types of clothing.
You should also air them out after washing them, as the heat of a dryer will wear down the elasticity and sweat-wicking functions of your workout gear. It will also warp and stretch the shape of your gym clothes, diminishing the compressing function that makes them so functional. If the dryer is an absolute must because you’re short on time, put it on the lowest, gentlest setting possible, but try not to make a habit of this.