Nike Girls HydraStrong Strive Racing Kneeskin Size Guide

This size guide covers the Nike Girls' HydraStrong Strive Racing Kneeskin. Engineered for the elite junior competitor, this suit is fully World Aquatics (FINA) approved for official racing and U12 compliant, with stitched seam construction that satisfies youth competition textile rules.

Built from Nike's ultra-durable HydraStrong fabric, it delivers targeted muscular compression and an optimised hydrodynamic profile to reduce drag. The open-back design and seamless V-back straps ensure a secure, zero-distraction fit with a maximum, unrestricted range of motion on every stroke. Flat-locked seams prevent chafing during intense efforts.

Select your size using your child's height, chest, waist, hips, and torso measurements. Age is shown as a guide only — always use body measurements as children develop at different rates.

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Body Measurement Points

How to Measure

Take all measurements directly against your child's skin using a soft tape measure. Age ranges are a guide only — always use body measurements. Use the torso measurement as the primary guide for kneeskins as it determines how the suit sits across the shoulders and through the body.

A
HeightMeasure your child's full standing height without shoes, from the crown of the head to the floor.
B
ChestMeasure around the fullest part of the chest, keeping the tape horizontal and snug but not tight.
C
WaistMeasure at the narrowest part of the natural waist, typically the small of the back.
D
HipsMeasure around the fullest part of the hips and seat, keeping the tape horizontal.
E
TorsoMeasure from the midpoint of the shoulder, over the bust, through the legs and up the back to the starting point. This is the primary guide for kneeskin sizing.

Age is a guide only. If measurements fall between sizes, speak to a member of staff at Allens who will be happy to advise on the best fit.

Sizing Table — Nike Girls' HydraStrong Strive Kneeskin

Size	22Y / XXS–XS Ages 5–6	24Y / S Ages 7–8	26Y / M Ages 9–10	28Y / L Ages 11–12	30Y / XL Ages 13–14	32Y / XXL Ages 15–16
Body Measurements (cm)
Height	114–126	126–138	138–150	150–160	160–170	170–180
Chest	61–66	66–71	71–76	76–82.5	82.5–89	89–95
Waist	58.5–61	61–63.5	63.5–66	66–70	70–73.5	73.5–77.5
Hips	63.5–70	70–76	76–82.5	82.5–89	89–95	95–99
Torso	106.5–115.5	115.5–124.5	124.5–133.5	133.5–142	142–151	151–160
Body Measurements (inches)
Height	45–50	50–54	54–59	59–63	63–67	67–71
Chest	24–26	26–28	28–30	30–32.5	32.5–35	35–37.5
Waist	23–24	24–25	25–26	26–27.5	27.5–29	29–30.5
Hips	25–27.5	27.5–30	30–32.5	32.5–35	35–37.5	37.5–39
Torso	42–45.5	45.5–49	49–52.5	52.5–56	56–59.5	59.5–63

Age ranges are a guide only. All measurements are body measurements, not garment measurements. Use the torso measurement as the primary guide for kneeskin sizing. Speak to a member of staff at Allens if you are unsure.

Fit Notes — Nike Girls' HydraStrong Strive Kneeskin

Always use body measurements to select the correct size — age ranges are a guide only as children develop at different rates.
Use the torso measurement as the primary guide — this determines how the kneeskin sits across the shoulders and through the body without pulling or gaping.
The suit is World Aquatics (FINA) approved and U12 compliant — legal for all sanctioned competitive swimming events. Always check with your event organiser for any local age group rules.
The suit should be completely wrinkle-free when correctly fitted — any bunching or gathering indicates the suit is too large.
The open-back V-back straps should sit flat with no twisting — ensure the straps are correctly positioned before racing.
Allow 10–15 minutes to put on correctly for the first time. Take care with fingernails and jewellery to protect the fabric.
Do not use sunscreen, oils, or petroleum-based products before putting on the suit. Rinse in cold fresh water immediately after each use. Do not machine wash, tumble dry, iron, or dry-clean.
Unsure? Contact our team or call +44 1827 330600. Speak to a member of staff at Allens if you are unsure.

Frequently Asked Questions — Nike Girls' HydraStrong Strive Kneeskin

Measure your child's height, chest, waist, hips, and torso using a soft tape measure taken directly against the skin. Use the torso as the primary guide — it determines how the kneeskin sits across the shoulders and through the body. Age ranges are a guide only. Speak to a member of staff at Allens if you are unsure.

Always select by body measurements. The age ranges shown are a guide only — children of the same age can vary significantly in size. Measure all five dimensions and compare to the sizing table above, using the torso as the primary guide. If measurements fall between sizes, speak to a member of staff at Allens who will be happy to advise.

Yes — the Nike Girls' HydraStrong Strive Kneeskin is World Aquatics (FINA) approved and features the official QR code mark, making it legal for all sanctioned competitive swimming events. It is also U12 compliant, with stitched seam construction that satisfies youth competition textile rules. Always check with your event organiser for any local age group rules that may apply.

If your child's measurements fall between two sizes, speak to a member of staff at Allens who will be happy to advise on the best fit. The torso measurement is the most important factor — if it falls clearly within one size range, select that size even if other measurements are borderline.

Nike HydraStrong is a premium performance fabric engineered for competitive swimmers. It provides exceptional chlorine resistance, shape retention, and long-lasting elasticity — meaning the suit maintains its compression and coverage meet after meet. It is significantly more durable than standard swimwear fabrics, making it ideal for the rigorous demands of race-day use.

The kneeskin should feel firm and compressive but wearable throughout a full competition day. It should be completely wrinkle-free when correctly fitted — any bunching or gathering indicates the suit is too large. The V-back straps should sit flat with no pulling or twisting, and the leg hems should end above the knee. Allow 10–15 minutes to put on correctly for the first time.

The Nike HydraStrong Strive Kneeskin is a competition suit designed for racing. Using it for regular training will degrade the fabric and reduce its lifespan. Reserve it for races and competition warm-ups to preserve its compression and hydrodynamic properties. Nike offer a range of training swimsuits for everyday pool use.

Rinse the suit in cold fresh water immediately after every use to remove chlorine and salt. Do not machine wash, tumble dry, iron, or dry-clean. Store flat and dry, away from direct sunlight. Avoid contact with sunscreen, oils, and petroleum-based products before putting the suit on as these degrade the fabric. Handle with care when putting on and taking off to protect the HydraStrong material.