BodyKore GR639 Leg Curl/Extension

Leg extension curl machine—BodyKore GR639 Leg Curl/Extension

Need consistent quad and hamstring isolation—without swapping attachments or guessing setup? This leg extension curl machine solves one clear problem: it gives you repeatable, measurable knee extension and knee flexion work in one selectorized, commercial-grade station, with fast pin changes and fit adjustments that scale across users.

Leg extension curl machine overview

Direct answer: The BodyKore GR639 combines leg extension and leg curl in one selectorized unit with a 220 lb weight stack (upgradeable to 340 lbs), built for smooth motion and efficient training flow.

Why it matters in real gyms:

• Faster circuits: extension to curl with minimal downtime.
• Less clutter: one station replaces two separate machines.
• Cleaner coaching: the same setup logic repeats for every client.

Leg extension curl machine biomechanics

Direct answer: Good pivot alignment and pad placement keep the effort on the target muscles, not on uncomfortable joint mechanics.

Biomechanics research on leg-extension equipment shows that equipment mechanics—such as resistance pad placement and system geometry—can change knee joint loading.  This is why the GR639’s angled pads, pivot positioning, adjustable seat depth/angle, and multiple starting positions matter: they help you find a controlled line of pull and keep the thigh stable.

For rehab-minded buyers: open-chain knee extension is widely discussed after ACL reconstruction, and recent evidence and clinical viewpoints support that it can be used safely when timing, load, and range are selected appropriately.  Patellofemoral forces also vary by task and joint angle, so controlled tempo and smart range choices matter.  (If you’re recovering from injury, follow your clinician’s plan.)

Fit-first setup checklist (60 seconds)

• Align the machine pivot with your knee.
• Adjust the seat so your knee is supported, not jammed.
• Pick a starting position you can control smoothly.
• Secure the thigh roller so your hips stay down.
• Use a slow first set to confirm alignment.

Leg extension curl machine programming

Direct answer: Program it as “targeted volume you can track,” then progress load or reps while keeping the setup identical.

General resistance training guidance commonly starts at two non-consecutive days per week, scaling intensity to the person and goal.  For older adults, structured strength training is also widely supported when progression is gradual and technique is prioritized.

Fast start templates

• Hypertrophy: 3–4×8–12 extensions, then 3–4×10–15 curls; last reps controlled.
• Strength: 4–6×4–6 on one movement, then 1–2 lighter sets for pristine form.
• Recovery: 2–3×12–20 with a lighter load and smooth motion; stop well before pain.

Coaching cue that prevents “cheating”

If your hips lift or you swing the weight, reduce the load and refit the thigh roller.

Key features: leg extension curl machine

Direct answer: The GR639 is engineered for a smooth feel, fast adjustment, and stable daily use.

✅ 2-in-1 extension + curl station
✅ 220 lb stack; 340 lb upgrade option
✅ Angled pads for alignment
✅ Pivot placement for full contraction
✅ Adjustable seat depth and seat angle
✅ Multiple starting positions
✅ Adjustable thigh roller for stability
✅ Smooth selectorized pin changes
✅ Rolled steel oval tubing frame
✅ Thermoset powder-coated finish
✅ Cup/phone/key holder built in
✅ Commercial grade; 1000+ lb rating

Leg extension curl machine specs

Direct answer: A compact footprint with substantial structure and stack capacity.

• Dimensions: 68" x 50" x 65"
• Machine weight: 582 lbs
• Footprint: 24 sq ft
• Frame: rolled steel oval tubing
• Frame color: Black or Silver
• Weight stack: 220 lbs (upgradeable to 340 lbs)

Manuals and data sheets for the GR639 leg extension/leg curl are available upon request.

Leg extension curl machine delivery

Direct answer: Tennessee-based support, with nationwide U.S. shipping and planning help for homes, studios, corporate wellness rooms, and commercial facilities.

From our Tennessee headquarters, we help customers across all U.S. states coordinate delivery and placement. To request a quote or plan a build, visit Hamilton Home Fitness.

Selectorized weight-stack machines are valued because they eliminate plate handling and enable quick load changes for multi-user environments.  Basic care keeps the movement smooth:

• Wipe pads and touchpoints regularly.
• Inspect cables/pulleys on a schedule.
• Keep the stack area clear to protect the selector pin.

People also ask
Is a leg extension curl machine good for beginners? Yes—start light, dial in fit, and progress in small steps with consistent mechanics.

Is leg extension safe for knees? For many people, it can be—fit, range, load, and tempo matter. If you’re rehabbing an injury, follow clinician guidance.

How do I switch from curl to extension? Reposition the seat and pads so the pivot aligns with your knee and the contact point matches the movement; then choose a controlled start position.

What weight stack should I choose? 220 lbs fits most mixed-user settings; choose the 340 lb upgrade when stronger users or growth are expected.

If you want a premium, space-smart station that makes quad and hamstring work easy to coach and easy to repeat, the GR639 delivers—and it keeps your lower-body program consistent week after week.

Manuals

Leg Extension & Leg Curl - GR639

Data Sheets

Isolation Series Leg Extension/Leg Curl GR639