Exercises and muscles targeted

Exercise	Muscles Targeted
Leg Extension (bilateral)	Quadriceps - All Four Heads (Rectus Femoris, Vastus Lateralis, Vastus Medialis, Vastus Intermedius, primary), Tibialis Anterior (secondary - dorsiflexion stabiliser at ankle), Hip Flexors (stabiliser through seated position)
Leg Extension (unilateral)	Quadriceps - Unilateral (one leg working to failure independently, primary), VMO - Vastus Medialis Oblique (terminal extension emphasis at 0-30 degrees), Rectus Femoris (hip flexion stabiliser in seated unilateral extension)
Leg Extension - Isometric Hold (peak)	Quadriceps - Full Contraction (sustained isometric at full knee extension, maximum VMO and Vastus Lateralis activation), Tibialis Anterior (sustained), Rectus Femoris (co-contraction stabiliser)
Leg Extension - Slow Eccentric	Quadriceps (eccentric loading through full knee flexion return, maximum hypertrophy stimulus at lengthened position), Rectus Femoris (increased eccentric demand as the hip flexed position lengthens the muscle at both ends)
Alternating Leg Extension	Quadriceps - Alternating (one leg extends while the other returns, continuous time under tension with independent arms), Core (increased anti-rotation demand during alternating asymmetric loading), Hip Flexors (sustained stabiliser through alternating seated extension)

The seated leg extension is the only exercise that isolates the quadriceps through pure knee extension without any hip extension contribution from the glutes or hamstrings. All four quad heads cross the knee joint and contribute to knee extension, making the leg extension the most complete quad isolation tool available. The independent arm design on the DSH017 makes it uniquely effective for identifying and addressing left-right quad strength differences that bilateral machines mask - a common asymmetry in athletes and lifters that contributes to knee tracking issues and unilateral lower body strength deficits.

Who this machine is built for

Serious Home Gym Builders
The DSH017 occupies a 63.0" × 63.0" square footprint and delivers plate-loaded quad isolation with independent bilateral arms at the same Olympic plate standard as every other machine in the setup. For a home gym that has squat and leg press coverage, the DSH017 adds the isolated quad stimulus that compound movements cannot replicate at equivalent targeted load.

Bodybuilders and Physique Athletes
Quadriceps detail — the visible separation between the four quad heads and the VMO sweep at the inner knee — develops through isolated knee extension under progressive plate resistance. The independent bilateral arms ensure both quads develop equally, and the alternating extension variation adds continuous time under tension across both legs without bilateral compensation reducing the stimulus on either side. The slow eccentric variation produces the lengthened-position quad hypertrophy stimulus that squats and leg presses cannot generate with the same specificity.

Powerlifters and Strength Athletes
Isolated quad work through knee extension addresses the VMO and terminal extension strength that supports squat lockout and knee stability under heavy bilateral loads. The DSH017 allows this to be trained with progressive plate loading at working loads that bodyweight and light resistance band terminal extension work cannot approach, and the unilateral format reveals any asymmetries that may be contributing to uneven squat depth or knee tracking under load.

Commercial Gym Owners and Operators
A plate-loaded independent arm leg extension machine covers the quad isolation category at the premium plate-loaded tier above selectorized leg extension alternatives. Members who train quads seriously — and especially those who have outgrown selectorized stack limits — seek out a plate-loaded alternative that allows genuine heavy progressive overload in the leg extension. The independent arms also give trainers a tool for assessing and programming around left-right quad imbalances in a commercial client population.

Physical Therapists and Sports Medicine Practitioners
The leg extension is a primary tool in quadriceps rehabilitation after ACL reconstruction, patellofemoral syndrome management, and post-surgical quad activation protocols. The infinitely adjustable backrest on the DSH017 allows the knee-to-pivot alignment to be optimised for each patient's anatomy and the specific range of motion that is safe for their stage of rehabilitation. Exercise selection and loading must follow the clinical programme and physician guidance for each patient's specific condition.

University and College Athletic Departments
Quad isolation and terminal extension strength is directly relevant to jumping, sprinting acceleration, and deceleration force absorption in virtually every team sport. The DSH017 provides this at plate-loaded bilateral loads with independent arms that make per-leg strength tracking and programming straightforward, supporting unilateral leg strength symmetry as a specific athletic performance and injury prevention target.

How to setup and use

Setting Up the DSH017 Leg Extension

Load Olympic plates evenly onto both weight horns, keeping amounts equal on each side within the 661 lb bilateral capacity. Start conservatively on the first session to confirm the working load for isolated quad training at the adjusted knee alignment.
Sit on the wide seat pad and slide the backrest to the position that places the back of the knee at the front edge of the seat pad, with the knee joint directly above the arm pivot axle. Use the infinite slide adjustment to find this position precisely — do not approximate it.
The correct knee-to-pivot alignment is the single most important setup step. If the knee is positioned forward of the pivot, the resistance arc will load the quad in only part of the extension range. If behind, the ankle pad will slide during the extension.
Place both lower legs behind the foam ankle rollers, confirming the rollers sit comfortably across the shin above the ankle rather than on the ankle bone itself.
Grip the side handles lightly for upper body stability - the grips anchor the torso without actively pulling during the extension.
For unilateral training, keep one leg passive against its ankle roller and extend only the working leg through the full arc before switching sides.

Performing the Exercise

From the starting position with the knees bent and the quads in a stretch, extend both legs simultaneously by contracting the quads and driving the lower legs upward against the ankle rollers through the full arc to complete knee extension.
Hold the peak extended position for one to two seconds with the quads fully contracted before beginning the return.
Lower both legs back to the starting position under control over at least two seconds, allowing the full quad stretch to develop at the bottom before the next rep.
For slow eccentric work, lower over four to five seconds on each rep. The eccentric phase under load at the lengthened quad position produces significant hypertrophy stimulus.
Avoid locking the knee hard at peak extension, reach full extension under muscle control rather than snapping the joint to end range.

Owner's Manual

Access the complete assembly guide, parts list, and maintenance schedule below.

Download Owners Manual

Shipping & Delivery

All Dynasty Fitness equipment ships free across the 48 contiguous US states via freight carrier. If the product description says preorder, we'll send you an estimated delivery date via email.

Estimated delivery: 7–14 business days from order confirmation. You will receive a tracking number and a delivery window confirmation call before your shipment arrives. Deliveries are curbside standard, white glove delivery to room of choice is available at checkout.

Returns: Free within 30 days of delivery. Items must be in original condition and packaging. Refunds processed within 5 business days of return receipt.

Questions? Contact our team at:
📧Email: info@thedynastyfitness.com
📞Call: +1 (213)-584-0858

Need a buying guide?

Looking for one to one support before making final decision?
Feel free to contact us. Our expert support team would love to assist you.

Need Installation Help?

We have partnered with another company to help provide installation around the country. Please use the link below to see the price per machine for installation
See Installation Rates

Payment & Security

Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.

Save 10%

Leg Extension DSH017

$1,989.00

$1,989.00 ~~$2,219.00~~ 10% off (Save$230.00 )

Commercial Grade
Pay With HFA/FSA

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The Dynasty Fitness DSH017 Leg Extension is a plate-loaded quadriceps machine with independent left and right arm frames on four ball bearings that train each leg separately against its own bilateral weight horn, eliminating the stronger quad from compensating for the weaker one across every rep. The arm frames carry counterweights that offset the mechanical weight of each arm so the effective resistance at the starting position matches the plate load precisely, and ergonomically shaped FOAM ankle rollers follow the natural movement arc of the lower leg for smooth, consistent quad activation through the full extension range. An infinitely adjustable backrest slides on inner and outer slides with three rollers to position the knee joint at the correct alignment with the arm pivot for each user's leg length — the defining adjustment that determines whether the resistance arc loads the quad through its full range or only part of it. Built from PT60×120×2.5mm steel with a 661 lb bilateral load capacity in matte black at 63.0" × 63.0", the DSH017 is built for commercial gyms, personal training studios, and serious home gym setups where dedicated plate-loaded unilateral quadriceps isolation is a training priority.

Plate-loaded leg extension with independent bilateral arm frames at up to 661 lbs total, each leg trains against its own weight horn with no compensation from the other side, making left-right quad strength differences visible and programmable from the first session
Counterweights on each arm frame offset the arm's mechanical weight so the effective resistance at the starting position equals the plate load rather than plates plus arm, keeping load targets accurate across every working set
Infinitely adjustable backrest on a three-roller slide system positions the knee precisely at the arm pivot for each user's leg length. The alignment that determines whether the quad is loaded through the full extension arc or only through a shortened partial range
Ergonomically shaped foam ankle rollers align with the natural lower leg movement path through the extension arc, maintaining consistent pad contact and load transfer from the starting bent-knee position through to full quad contraction at peak extension

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Exercises and muscles targeted

Exercise	Muscles Targeted
Leg Extension (bilateral)	Quadriceps - All Four Heads (Rectus Femoris, Vastus Lateralis, Vastus Medialis, Vastus Intermedius, primary), Tibialis Anterior (secondary - dorsiflexion stabiliser at ankle), Hip Flexors (stabiliser through seated position)
Leg Extension (unilateral)	Quadriceps - Unilateral (one leg working to failure independently, primary), VMO - Vastus Medialis Oblique (terminal extension emphasis at 0-30 degrees), Rectus Femoris (hip flexion stabiliser in seated unilateral extension)
Leg Extension - Isometric Hold (peak)	Quadriceps - Full Contraction (sustained isometric at full knee extension, maximum VMO and Vastus Lateralis activation), Tibialis Anterior (sustained), Rectus Femoris (co-contraction stabiliser)
Leg Extension - Slow Eccentric	Quadriceps (eccentric loading through full knee flexion return, maximum hypertrophy stimulus at lengthened position), Rectus Femoris (increased eccentric demand as the hip flexed position lengthens the muscle at both ends)
Alternating Leg Extension	Quadriceps - Alternating (one leg extends while the other returns, continuous time under tension with independent arms), Core (increased anti-rotation demand during alternating asymmetric loading), Hip Flexors (sustained stabiliser through alternating seated extension)

Who this machine is built for

How to setup and use

Setting Up the DSH017 Leg Extension

Load Olympic plates evenly onto both weight horns, keeping amounts equal on each side within the 661 lb bilateral capacity. Start conservatively on the first session to confirm the working load for isolated quad training at the adjusted knee alignment.
Sit on the wide seat pad and slide the backrest to the position that places the back of the knee at the front edge of the seat pad, with the knee joint directly above the arm pivot axle. Use the infinite slide adjustment to find this position precisely — do not approximate it.
The correct knee-to-pivot alignment is the single most important setup step. If the knee is positioned forward of the pivot, the resistance arc will load the quad in only part of the extension range. If behind, the ankle pad will slide during the extension.
Place both lower legs behind the foam ankle rollers, confirming the rollers sit comfortably across the shin above the ankle rather than on the ankle bone itself.
Grip the side handles lightly for upper body stability - the grips anchor the torso without actively pulling during the extension.
For unilateral training, keep one leg passive against its ankle roller and extend only the working leg through the full arc before switching sides.

Performing the Exercise

From the starting position with the knees bent and the quads in a stretch, extend both legs simultaneously by contracting the quads and driving the lower legs upward against the ankle rollers through the full arc to complete knee extension.
Hold the peak extended position for one to two seconds with the quads fully contracted before beginning the return.
Lower both legs back to the starting position under control over at least two seconds, allowing the full quad stretch to develop at the bottom before the next rep.
For slow eccentric work, lower over four to five seconds on each rep. The eccentric phase under load at the lengthened quad position produces significant hypertrophy stimulus.
Avoid locking the knee hard at peak extension, reach full extension under muscle control rather than snapping the joint to end range.

Owner's Manual

Access the complete assembly guide, parts list, and maintenance schedule below.

Download Owners Manual

Shipping & Delivery

All Dynasty Fitness equipment ships free across the 48 contiguous US states via freight carrier. If the product description says preorder, we'll send you an estimated delivery date via email.

Returns: Free within 30 days of delivery. Items must be in original condition and packaging. Refunds processed within 5 business days of return receipt.

Questions? Contact our team at:
📧Email: info@thedynastyfitness.com
📞Call: +1 (213)-584-0858

Need a buying guide?

Looking for one to one support before making final decision?
Feel free to contact us. Our expert support team would love to assist you.

Need Installation Help?

We have partnered with another company to help provide installation around the country. Please use the link below to see the price per machine for installation
See Installation Rates

Payment & Security

Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.

Leg Extension DSH017

$1,989.00

$1,989.00 ~~$2,219.00~~ 10% off (Save$230.00 )

Key Features

Independent Bilateral Arm Frames

Left and right arm frames pivot on four ball bearings across two arm pivot axles, each arm working completely independently against its own weight horn load. Neither leg can assist the other. The stronger quad works its resistance and the weaker works its own, making the DSH017 one of the few leg extension machines where left-right quad strength differences are automatically separated rather than averaged. Two counterweights offset the mechanical arm weight on each side so effective resistance matches the plate load from the first degree of extension.

Infinitely Adjustable Backrest

The back pad frame slides on inner and outer slides with three rollers, adjusting to any position along the rail via the backrest adjustment mechanism. The knee-to-pivot alignment this controls is the most critical fit variable on a leg extension even a few centimetres of misalignment shifts when in the extension arc the resistance peaks and where it is minimal. Infinite adjustment ensures the correct position is found and held for each user rather than selected from the closest of a limited number of indexed positions.

Ergonomic Foam Ankle Rollers

Two foam ankle rollers are shaped to follow the natural arc of the lower leg through the knee extension movement. A flat-surface roller presents a fixed contact edge that changes its pressure point on the shin as the lower leg angle changes through the extension arc. The ergonomically contoured foam surface maintains consistent contact with the shin throughout the full extension range, keeping load transfer to the quad consistent from the bent-knee starting position through to full extension at the top.

Wide Seat Pad and Side Grips

The wide seat pad accommodates different leg circumferences and provides stable bilateral seating contact that prevents the hips from lifting during maximum-effort unilateral extension. Two side grips allow light hand bracing that anchors the torso without creating pulling tension that would transfer load away from the working quads. The seat and grip combination keeps the upper body neutral and still so the quad extension is the only movement occurring during each rep.

Product Information
Product Name	Leg Extension
Model	DSH017
Series	DSH Plate Loaded Series
Product Type	Plate-Loaded Seated Leg Extension Machine
Primary Function	Bilateral or unilateral seated leg extension — quadriceps isolation through knee extension
Target Muscles	Quadriceps — Rectus Femoris, Vastus Lateralis, Vastus Medialis, Vastus Intermedius (primary)
Training Mode	Bilateral or unilateral — independent left and right arm frames
Grade	Commercial
Colour	Matte Black
Dimensions and Weight
Length	63.0 in (160.0 cm)
Width	63.0 in (160.0 cm)
Height	49.6 in (126.0 cm)
Net Weight	243 lbs (110 kg)
Load Capacity
Maximum Load Capacity	661 lbs (300 kg) — 330 lbs (150 kg) per side
Loading System	Plate-loaded — Olympic plates, 2 bilateral weight horns
Arm System
Arm Frames	2 x independent — left and right arm frames
Arm Pivot Bearings	Ball bearings x4 — 2 per arm pivot axle
Counterbalance	Counterweights x2 — one per arm, offsets arm mechanical weight
Adjustability and Pads
Backrest Adjustment	Infinitely adjustable — inner and outer slide system with 3 rollers
Ankle Rollers	Ergonomic foam x2 — follow natural lower leg movement arc
Seat Pad	Wide — accommodates varying leg circumferences
Side Grips	x2 — upper body anchoring during extension sets
Frame and Construction
Main Frame Tubing	PT60×120×2.5mm rectangular steel
Levelling Foot	1 x adjustable
Floor Feet	3 x rubber feet
Finish	Matte black powder coat
Indoor Use Only	Yes

Q: Why does the backrest position matter so much on a leg extension machine?
A: The backrest position determines where the knee sits relative to the arm pivot axle. When the knee is aligned directly over the pivot, the extension arc loads the quad through the full range from the bent-knee starting stretch through to full extension at the top. If the knee is too far forward or backward of the pivot, the resistance peaks at the wrong point in the range and the quad is only loaded effectively through part of the arc. The infinite adjustment on the DSH017 allows this alignment to be found exactly rather than approximated, which is why correct backrest setup produces a noticeably different training quality than a mis-set machine.

Q: How do I set the backrest correctly?
A: Sit on the seat and slide the backrest until the back of the knee sits at the front edge of the seat pad, with the knee joint positioned directly above the arm pivot axle when viewed from the side. The knee should not overhang the seat edge forward, nor should there be a significant gap between the back of the knee and the seat edge. Confirm by extending one leg slowly through the arc at very light load — the resistance should feel consistent through the full range rather than easy at one end and hard at the other.

Q: What is the benefit of training each leg independently on a leg extension?
A: Bilateral leg extensions allow the stronger quad to partially stabilise and compensate for the weaker quad through shared timing and momentum. When each arm is fully independent, the stronger and weaker legs must each complete the full extension under their own load with no assistance. This reveals the actual strength difference between legs as a measurable rep or load difference, which a bilateral machine masks. Addressing this asymmetry with equal loading on both sides until symmetry is restored reduces the quad imbalance that underlies many knee tracking and patellofemoral issues.

Q: Is the leg extension safe for knee health?
A: The leg extension is safe for healthy knees when the pivot alignment is set correctly and the range of motion is controlled. The machine design on the DSH017 keeps the tibia in a fixed extension path through the arc, which is a controlled environment that allows load and range to be progressed systematically. Users with existing knee concerns should consult a clinician before beginning leg extension training — some conditions benefit from terminal extension only (the last 30 degrees), while others may require full range, and the appropriate protocol depends on the specific condition.

Q: How does the Leg Extension DSH017 differ from the Leg Extension Prone Leg Curl DSA031?
A: The DSH017 is a plate-loaded machine with independent bilateral arms for both bilateral and unilateral training at up to 661 lbs. The DSA031 is a selectorized machine that covers both leg extension and prone leg curl from one station via a weight stack. The DSH017 is suited to users who want heavy plate-loaded progressive loading and independent arm unilateral training. The DSA031 suits facilities that want both quad and hamstring isolation from one compact selectorized station with rapid weight stack adjustment.

Q: What Dynasty Fitness machines pair with the DSH017 for complete quad and lower body training?
A: The DSH017 covers quad isolation through knee extension. Pair it with the Kneeling Leg Curl DSH014 for hamstring isolation through the hip-extended kneeling curl that complements the seated extension. The Hack Squat DSH036, Pendulum Squat DSH033, and V-Squat DSH038 add bilateral quad compound volume through squat-pattern loading. The 45 Degree Linear Leg Press DSH019 and Vertical Leg Press DSH043 cover bilateral pressing volume alongside the isolated extension work. Together these stations cover the quadriceps from compound bilateral pressing through to isolated unilateral extension.

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Every machine that leaves Dynasty Fitness carries the same promise: it is built to the commercial standard that professional training environments demand, priced so that standard is no longer exclusive to them, and backed by the support and warranty coverage that a long-term training investment deserves.

We are committed to equipment that stands the test of time — and to making sure the people who train the hardest have access to the tools that match their effort.