The “thermal burden” associated with a normal sports bra can be ruinous, even for an event as short as a mile. Ms. Kipyegon’s bra is made from FlyWeb, a 3D-printed thermoplastic polyurethane material that is better at minimizing sweat retention than other textiles. The bra was developed over two years and is the first 3D-printed bra Nike has ever made.

Weblike in its construction and “featherlight,” according to Janett Nichol, vice president of Nike’s apparel innovation unit, the bra had to be soft and supportive “yet also feel like you are not wearing anything at all.”

The bra also had to be incredibly thin in order to reduce aerodynamic drag under Ms. Kipyegon’s fly suit. The racer-back style allows for more range of motion while running than two shoulder straps would.

Ms. Kipyegon will be the first athlete to wear the bra in competition, but the plan is to offer the FlyWeb bra to other athletes across various sports and, subject to testing, possibly bring a version of the bra to consumers by 2028.

Running shoes like these are known as “spikes” because of the spikes on the soles that can enhance grip and traction and that enable athletes to accelerate quickly and maintain their stability.

The spikes worn by Ms. Kipyegon for her 1,500-meter gold medal run in 2024 and for her world record for the mile in 2023 were called the Nike Victory 2. After feedback from Ms. Kipyegon, her new spikes, which have a taller and lighter design than their predecessor, became known as the Nike Victory Elite FK. (FK refers to Ms. Kipyegon’s initials and also stands for Fastest Known.)

Each shoe weighs 85 grams, which is about 25 percent lighter than the Victory 2 design. They also have the tallest air unit — the foam cushioning on the sole designed to decrease impact on athletes’ joints — ever built into a track spike.

Because Nike didn’t have to worry about durability or the prohibitive costs of commercialization for this one-off design, it was able to work with materials it doesn’t usually use. The FlyKnit upper material is more open in its knit structure, and each spike weighs just three grams — or the weight of about three paper clips.

Carrie Dimoff, the footwear product director at Nike Innovation, said that because the spikes were lighter and had new features, Ms. Kipyegon could “increase her energy return and improve her running efficiency.” The shoe’s outsole plate has six titanium spikes, compared with five on the Victory 2.

Titanium is lighter than steel and stronger than aluminum, the primary metals used in running spikes. The six spikes are embedded in carbon fiber layers on the plate rather than screwed in, creating a more seamless integration underfoot.

Nike said that the shoe would conform to World Athletics regulations, but it has not been submitted for approval. This could raise questions for the governing body when determining whether to ratify the run as a record.