Manufacturing Gymshark-Style Seamless Activewear: Santoni Knitting, Contour Shading & OEM Sourcing

Gymshark transformed modern fitness apparel by pioneering body-contouring seamless activewear. By eliminating traditional cut-and-sew side seams and engineering multi-density jacquard knit patterns directly onto circular knitting machines, they created garments that sculpt the physique, enhance muscular definition, and endure high-intensity gym training.

If you are building a fitness apparel brand targeting gym enthusiasts, powerlifters, or high-energy studio trainers, this technical manufacturing guide explains how to program Santoni seamless knitting machines, design flattering contour shading, and source high-margin Gymshark-grade collections.

1. The Santoni Circular Knitting Revolution: How Seamless Is Built

Unlike traditional cut-and-sew garments where flat fabric is cut into panels and sewn with overlock machines, seamless activewear is produced as a continuous 3D tubular knit using advanced electronic circular knitting machines:

• Santoni SM8-TOP2V / SM8-TR1 Electronic Machines: GiftMoss utilizes high-speed Italian-engineered Santoni 8-feed circular machines equipped with individual needle selection across 28-gauge to 32-gauge cylinders (13" to 17" cylinder diameters).
• Tube-to-Garment Conversion: The machine knits a seamless cylinder containing pre-programmed variable stitch densities, waistband compression bands, ribbed texture zones, and breathability mesh eyelets in a single continuous process.
• Minimal Assembly Seams: The only sewing operations required are joining the inner leg inseam and attaching the crotch gusset with 4-needle 6-thread flatlock stitching. Side seams, outer hip seams, and sewn waistband attachments are completely eliminated.

2. Body-Mapping Jacquard & Glute Contour Shading

The hallmark of Gymshark's Vital Seamless and Adapt collections is the signature under-glute shadow contour and thigh-slimming side panels. These are not printed onto the garment — they are programmed directly into the knitting CAD software:

• Stitch Density Variation (Piqué vs. Plain Knit): By alternating between tight tuck stitches, open piqué loops, and dense flat knit structures, the machine creates natural light-and-shadow visual effects using yarn tension alone.
• Two-Tone Marl Plating (Space-Dye Yarn): Feeding a darker micro-polyamide yarn through the rear feeder and a lighter space-dyed yarn through the face feeder produces dimensional heathered textures with deep contrast shading.
• Under-Glute Lifting Ribs: A localized crescent-shaped zone of tighter compression knit sits directly underneath the gluteal fold, providing physical lift and visual accentuation without requiring uncomfortable internal padding.

3. Multi-Zone Gradient Compression & Ribbed Structures

A high-performance gym legging must deliver structural core support around the abdomen while allowing unrestricted mobility at the knees and hips. Seamless technology achieves this through zoned tension programming:

1. Zone 1: Reinforced Ribbed Waistband (High Compression): Knitted with double-core 70D Lycra in a 2x2 rib structure to provide firm tummy control that stays locked in place during heavy deadlifts.
2. Zone 2: Quadriceps & Hamstring Panels (Medium Compression): Engineered plain jersey knit that holds muscle groups firmly to minimize energy loss from soft-tissue vibration.
3. Zone 3: Popliteal & Calf Mesh Panels (Light Compression & Ventilation): Open jacquard micro-eyelets placed behind the knees and along the lower calves to maximize airflow and evaporate perspiration instantly.

4. Microfiber Core-Spun Yarn Blends for Maximum Durability

Gym environments involve harsh abrasive contact with knurled barbell grips, bench press upholstery, and floor friction. The yarn composition must be rugged yet soft to the touch:

• Yarn Architecture: 60%–65% Polyamide 6.6 Microfiber (Nylon 6.6), 25%–30% Cationic Polyester (for multi-tone marl effects), and 10%–15% Air-Covered Elastane (Lycra®).
• Air-Covered Spandex (ACY): The elastane core is continuously enveloped by surrounding nylon microfilaments via pressurized air nozzles. This shields the elastane from body oils and chlorine, preventing rubber degradation and elasticity sag over time.
• Hydrophilic Wicking Finish: Pre-treated with moisture-management auxiliaries to pull sweat away from the skin and disperse it across the outer fabric surface for rapid evaporation.

5. Solving the Squat-Proof Opacity Challenge in Light & Pastel Colorways

Pastel seamless sets (e.g., Chalk Pink, Sage, Lilac) are highly popular but prone to transparency during deep squats. GiftMoss solves this through three factory-level countermeasures:

• Increasing Finished Fabric GSM to 310–330 g/m²: Higher knitting density packs more yarn loops per square centimeter, preventing light transmission when stretched.
• High-Gauge 32G Needle Cylinders: Finer needles create micro-tight loop interlocks that do not spread apart under horizontal tension.
• Dope-Dyed Interior Yarn Layer: Using high-opacity semi-dull interior yarns prevents skin tones and dark underwear from reflecting through the outer knit.

6. Tech Pack Blueprint & Small-Batch OEM Sourcing

Launching a seamless fitness line does not require ordering 1,000 units per color. GiftMoss offers agile OEM programs designed for growing fitness brands: