4004A Seated Leg Extension—Wholesale Pricing

Model 4004A Seated Leg Extension — Wholesale Pricing, Bulk Order Specifications, and OEM Procurement Guide

Model 4004A Seated Leg Extension — Wholesale Pricing, Bulk Order Specifications, and OEM Procurement Guide

The seated leg extension remains one of the highest-rotation selectorized stations on a commercial strength floor. It isolates the quadriceps through a single, easy-to-coach movement pattern, demands almost no member instruction, and accepts a broader range of user sizes and ability levels than any compound leg alternative. For procurement teams, that combination translates into predictable throughput, low supervision burden, and a unit that pays back its cost in utilization rather than novelty.

The model 4004A seated leg extension is built around a selector-pin weight system with an 80 kg internal stack, a fully enclosed tower shroud, and an adjustable start position. The specification sheet positions it for commercial gyms, hotel fitness rooms, corporate wellness centers, apartment and condominium gyms, school athletic facilities, and wholesale distribution. This guide covers the technical data that matters at the quotation stage, the biomechanics buyers should understand before comparing alternatives, layout and logistics planning, maintenance economics, and the questions distributors and operators raise most often.

Specification Sheet

What Makes a Leg Extension Commercial Grade

A leg extension looks mechanically simple, but it is one of the most demanding selectorized designs in a catalogue. Every repetition moves the full stack weight through a long arc at high angular velocity, and the machine must remain rigid while absorbing eccentric load from members of widely different body mass. That is why assembled mass is a meaningful specification: the 4004A ships at 198 kg, which places it in the category associated with stable commercial platforms rather than residential-grade alternatives.

The frame is built from heavy-gauge flat-oval steel tube with a full-welded construction. Post-weld treatment begins with grit blasting to guarantee coating adhesion, followed by a furnace-baked, heat-cured, dual-layer electrostatic epoxy powder coat. The two-layer system matters more than the color choice: it provides coating thickness, corrosion resistance, and a surface that can be cleaned repeatedly without lifting.

The main pivot runs on sealed bearings, and the resistance path is governed by an eccentric cam. A circular pulley delivers constant resistance, which feels disproportionately heavy near terminal extension. An eccentric cam varies the cable radius so that resistance rises through the mid-range and reduces toward full extension, matching the quadriceps strength curve and keeping tension consistent without a hard sticking point.

The stack tower is fully enclosed with a front shroud and a magnetic, tethered selector pin. That enclosure is a safety feature as much as an aesthetic one: it prevents bystander contact with moving plates and keeps foreign objects out of the guide rods. The selector pin itself is tethered so it cannot be removed and misplaced.

Biomechanics and the Knee-Pivot Alignment Question

The human knee is not a simple hinge. Its axis of rotation shifts as the tibia moves relative to the femur, following a curve described by the instantaneous center of rotation. A fixed machine pivot can only approximate that curve, and the quality of that approximation determines whether the shin pad tracks cleanly or slides along the tibia during the set.

The adjustment system on the 4004A — adjustable seat pad, adjustable back pad, multiple start positions, and a self-aligning ankle roller — exists to solve exactly this problem. The operational instruction is straightforward: align the lateral femoral epicondyle, the bony point on the outside of the knee, with the machine's pivot center. When the axes match, the machine's angular velocity equals the limb's angular velocity, the force vector stays perpendicular to the tibia, and parasitic shear is minimized.

Alignment errors are measurable. A pivot placed too far forward increases compressive load on the patellofemoral joint. A pivot placed too far backward increases anterior draw on the tibia and raises tensile stress on the anterior cruciate ligament, particularly through the final 15 degrees of extension. Floor staff should be trained to check alignment rather than simply handing members a pin.

The external moment arm also changes with knee angle. In a seated leg extension, the distance from the knee joint to the shin pad defines that lever arm: a more distal pad position increases the lever and requires less stack weight to produce high muscle tension, but it also raises shear at the knee. Pad placement is therefore not a comfort adjustment — it changes the load profile of the exercise.

A second point is worth addressing directly. The leg extension has acquired a reputation for being inherently harsh on the knees, but the research does not support treating it as uniquely hazardous. Comparative biomechanics data shows that patellofemoral stress is actually higher in a squat than in a seated leg extension through the 90-to-45-degree knee-flexion range. The practical implication is not that one movement replaces another; it is that members with sensitive patellofemoral joints can often train productively through a limited range, while progressive loading is appropriate for healthy members seeking adaptation.

How the 4004A Fits Into a Leg Lineup

The leg press is the stronger default for overall lower-body strength. It is a closed kinetic chain movement that recruits quads, hamstrings, glutes, and calves together, permits heavier absolute loading, and offers manipulation through foot placement. Its limitations are floor area and technical setup: it requires more space, and poor bracing can increase spinal compressive load.

The leg extension is the stronger choice for targeted quad work. It teaches neuromuscular control, permits higher repetition ranges with minimal systemic fatigue, and serves as an effective finisher after compound work. It also provides a controlled environment for members who cannot or should not load the spine and hips. The two machines are complementary rather than competitive, and most well-specified selectorized lines carry both.

Footprint, Layout, and Freight Planning

The assembled footprint of the 4004A is 1426 × 1156 mm, or 1.65 m². For layout planning, allow a 1 m clearance on the access sides, giving a planned envelope of approximately 2.4 × 2.2 m per unit. The height of 1524 mm places it under a standard 2.4 m ceiling with comfortable clearance, though ceiling-mounted equipment and services should be checked before final placement.

The packing dimensions of 1.6 × 1.2 × 0.65 m and a carton volume of 1.248 m³ are the figures to use for freight calculations. At 198 kg gross, this is a heavy single-item crate. A forklift or pallet jack is required at the receiving end, and door widths, elevator capacities, and corridor turns should be confirmed before shipment. Standard export packing uses bubble wrap, stretch film, and a wooden crate; EPE foam is available where specified.

Container dispatch is rapid once production is running. Published schedules show five days for a single unit, 15 days for a 20 ft container, and 25 days for a 40HQ container, with the usual qualification that quantity and customization affect the actual dispatch date. Mixed-container shipments are supported, which matters for distributors consolidating a full selectorized line.

Pricing, Payment, and Commercial Terms

Wholesale pricing is structured around order volume. Published manufacturer schedules show commercial selectorized units in the 500 to 600 USD range at 10-piece volume, with sample pricing around 700 USD per unit. These are supplier-listed figures rather than fixed quotations, and the 4004A price should be confirmed against current steel, coating, and logistics costs at the time of order.

The standard payment structure is T/T with 30% deposit and 70% balance before delivery. Western Union and cash are listed alternatives with some suppliers. Incoterms commonly offered include EXW, FOB, CIF, and DDP; the choice materially changes landed cost and should be specified in the pro forma rather than assumed.

OEM and ODM services cover frame color, cushion color, logo engraving, and specification adjustment for bulk orders. Minimum order quantities for customized production should be confirmed at quotation. English manuals, installation videos, and spare-parts supply are standard inclusions.

Buyers preparing tender submissions should request CE, ISO, and SGS documentation in advance. These certificates are commonly available on request but are not automatically attached to every shipment.

Maintenance and Consumables

The service life of a selectorized leg station is governed by its consumable replacement cycle. The highest-wear items are the cable, selector pin, guide rods, pulley system, and upholstery. A maintenance log is the difference between a controlled replacement and an emergency repair during peak hours.

A workable schedule: daily visual inspection of the cable for strand separation and of upholstery for tears; weekly confirmation that the selector pin seats fully and the stack travels without obstruction; monthly re-greasing of guide rods, inspection of pivot bearings, and frame-bolt torque check; and quarterly review of welds, corrosion, and the full service record.

The warranty runs 3 years on the main frame and 1 year on other parts. Photographic records of delivery condition and serial numbers should be retained, since they are commonly required for warranty validation. Spare-parts kits are available and should be ordered with the initial shipment rather than after the first failure.

Programming and On-Floor Coaching

For general lower-body development, the conventional sequence is leg press first for 3–5 sets in the 6–12 repetition range, followed by leg extension for 2–4 lighter sets in the 8–15 range as a finishing movement. The leg extension contributes targeted quad volume and time under tension without adding systemic fatigue.

For members focused on definition and the distal quadriceps, the leg extension can carry more of the session. Moderate weight, a controlled eccentric, and a full contraction at the top produce the desired stimulus. Partial-range work can be useful, but it should be a deliberate variation rather than a compensation for insufficient load selection.

For members with a history of knee sensitivity, the available guidance supports training through the 90-to-45-degree range rather than through full terminal extension. Members should be advised to obtain clinical clearance for any specific condition, and on-floor trainers should treat pre-existing knee issues as a reason to reduce range rather than load.

Frequently Asked Questions

What muscle does the leg extension train?

The primary target is the quadriceps femoris. The movement isolates the quads through knee extension without recruiting the glutes, hamstrings, or calves to share the load, which is why it is used for targeted hypertrophy and shaping work.

Is the leg extension suitable for beginners?

It is one of the easiest selectorized movements to learn. The path is fixed, the adjustment is simple, and the resistance is selected with a pin. Beginners should start with moderate loads and higher repetitions while focusing on controlled tempo.

How important is knee alignment with the pivot?

It is the central setup requirement. The lateral epicondyle of the femur should align with the machine's pivot center. Misalignment changes the force vector and introduces shear at the knee joint. The adjustable seat, back pad, and start positions are designed to make this alignment achievable across different body sizes.

Can the range of motion be limited for members with knee sensitivity?

Yes. Training through the 90-to-45-degree range is commonly recommended where terminal extension causes discomfort. The padded shin roller and adjustable start positions support this kind of modification.

What is the difference between a standalone leg extension and a leg extension and curl combo?

A standalone unit dedicates the full frame to quadriceps isolation and typically offers a longer adjustment range and a larger stack. A combo unit places extension and curl on one frame, saving floor space at the cost of one movement at a time. The choice depends on available area and member demand.

What customizations are available for distributors?

Frame color, cushion color, logo placement, decals, and packaging can all be specified. OEM and ODM production supports both sample-based and drawing-based design input. Color matching is most reliable when the buyer supplies a Pantone reference or physical swatch.

What delivery terms are standard?

EXW, FOB, CIF, and DDP are commonly offered. The selected term determines who handles freight, insurance, and import clearance, so it should be confirmed in writing on the pro forma invoice.

What documentation should be requested for import and tender use?

CE, ISO, and SGS certificates, a commercial invoice, packing list, bill of lading, and an exploded parts diagram. Requesting these documents at the quotation stage prevents delays at customs and during tender submission.

A Note on Evaluation

The 4004A seated leg extension competes in a category where specifications diverge more than photographs suggest. Published alternatives range from approximately 189 kg to 250 kg assembled mass, from 80 kg to 110 kg stack weight, and from compact footprints under 1.1 m² to units exceeding 1.8 m². The variation is not cosmetic: it reflects different choices about stability, adjustment range, stack capacity, and floor efficiency.

Buyers should evaluate this model against written specifications for tube gauge, stack weight, cable diameter, guide-rod material, adjustment range, and warranty terms. A lower purchase price on a lighter frame is rarely the better value when the unit is expected to run through thousands of cycles per week. The questions that matter are how long the pivot stays smooth, how cleanly the stack travels, and whether spare parts will still be available in three years. Those are the criteria on which a procurement decision should rest.