Soft Tracksuits – Why the Material Matters

Short answer: How soft a tracksuit set feels is decided by the fibres and the knit. Sweat fabric with bamboo viscose is among the softest you can get, because the fibres are fine and smooth and because the inside is usually lightly brushed into an even, dense surface.

The fibres come first

The skin feels the number of fibre ends and not the name of the material. Short fibres give many ends that stick out and read as rough. Long, smooth fibres give few ends and a soft surface. That is the single factor that matters most to how a set feels.

The inside is what you feel

Sweat fabric is knitted so the inside can be brushed into a soft pile. That pile is what the skin touches, not the outside. A dense brushing in long fibres turns soft and stays soft, where a loose brushing collapses after a few washes and turns hard.

Weight and drape

A heavier fabric does not feel harder but calmer, because it lies still instead of following every movement. Sweat fabric with bamboo viscose is heavier than a comparable one in pure cotton, so it falls straight down and feels softer against the body.

Polyester is the problem

Many cheap sweat sets have a large share of polyester, because it is cheap and durable. The price is that the fabric does not breathe and turns clammy after two hours. See bamboo tracksuit sets for women and read the content label rather than the description.

The density of the knit

A densely knitted sweat fabric holds its shape better but can turn stiff if the knit is hard. A looser knit is softer and loses its shape sooner. The good set sits in between, and it can be felt by squeezing the fabric in your hand.

Ribbing at neck and wrist

The ribbing is where the skin feels the most pressure. Hard ribbing without stretch leaves a mark in the skin after an hour, and that is one of the most common reasons an otherwise soft top gets put away after a few wearings.

Softness that lasts

Because the softness of bamboo viscose comes from the shape of the fibre and not from a treatment, it does not wash out. A set feels much the same after twenty washes if it has not been in the tumble dryer. See the whole category under sweat clothing.

Fabric softener works against it

Softener feels soft at first, but it lays a film in the pile that collapses it and slows moisture transport. On sweat fabric the effect is clearer than on thin fabric, because there is more surface inside for the film to settle on.

How to keep the set soft

Wash at 30 degrees without fabric softener, turn the pieces inside out and hang them to dry. The tumble dryer collapses the pile and makes the ribbing brittle, and neither can be put right afterwards, however you wash next time. See also bamboo and temperature regulation and washing guide for bamboo clothing.