SGDS-72 Seated Leg Curl / Leg Extension

Professional Dual-Function Lower Body Machine

The SGDS-72 Seated Leg Curl / Leg Extension is a premium selectorized strength machine designed to provide complete isolation training for the quadriceps and hamstring muscle groups within a single compact unit. Engineered with advanced biomechanics and smooth resistance delivery, this machine allows users to perform both knee extension and knee flexion movements safely and effectively, making it an essential addition to commercial gyms, fitness clubs, rehabilitation centers, and performance training facilities.

Key Features

• Dual-function design: Leg Extension & Seated Leg Curl
• Heavy-duty 50 × 100 mm steel frame with 3 mm wall thickness
• Precision welded commercial-grade construction
• Smooth nylon pulley system
• Internally lubricated 6 mm aircraft-grade cables
• Electrostatic powder-coated finish (double coating process)
• Ergonomically contoured seat and back support
• Adjustable leg roller and starting positions
• Comfortable high-density foam padding
• Compact footprint with professional appearance

Biomechanical Design

The SGDS-72 is engineered around the natural biomechanics of the knee joint to maximize muscle activation while minimizing unwanted stress on ligaments and connective tissues.

Leg Extension Biomechanics

The leg extension movement is an open kinetic chain exercise where resistance is applied distally at the ankle while the user extends the knee.

Primary Joint Action: Knee Extension

Primary Muscles Activated:

• Rectus Femoris
• Vastus Lateralis
• Vastus Medialis
• Vastus Intermedius

Secondary Stabilizers: Hip Flexors, Core Stabilizers

The machine's pivot point aligns with the user's anatomical knee axis, creating a natural movement path that enhances quadriceps recruitment while reducing shear forces across the knee. The resistance profile provides consistent tension throughout the range of motion, helping users achieve greater muscular contraction, especially near full extension where quadriceps activation peaks.

Seated Leg Curl Biomechanics

The seated leg curl is considered one of the most effective hamstring exercises because it trains the muscles while they are placed in a lengthened position.

Primary Joint Action: Knee Flexion

Primary Muscles Activated:

• Biceps Femoris
• Semitendinosus
• Semimembranosus

Secondary Muscles: Gastrocnemius, Popliteus, Gluteal Stabilizers

The seated position places the hips in flexion, creating greater hamstring stretch and increasing muscle fiber recruitment compared to traditional lying leg curl designs. The machine's cam system maintains optimal resistance throughout the movement, ensuring continuous loading during both concentric and eccentric phases.

Kinesiology Benefits

Quadriceps Development

The leg extension movement effectively targets all four heads of the quadriceps, making it ideal for:

• Muscle hypertrophy
• Strength development
• Athletic performance enhancement
• Knee stabilization training
• Rehabilitation protocols

Special emphasis is placed on the Vastus Medialis Oblique (VMO), a critical muscle for patellar tracking and knee health.

Hamstring Development

The seated leg curl develops:

• Knee flexion strength
• Sprinting performance
• Explosive athletic movements
• Injury prevention
• Posterior chain balance

The seated position produces greater activation of the hamstring musculature due to increased muscle length during loading.

Movement Characteristics

• Resistance Type: Selectorized weight stack resistance
• Leg Extension: Open-chain knee extension
• Leg Curl: Open-chain knee flexion
• Strength Curve: Optimized to match the body's natural force production throughout the entire range of motion
• Range of Motion: Allows full physiological knee flexion and extension while maintaining proper joint alignment

Training Applications

Ideal For:

• Commercial Fitness Centers
• Luxury Health Clubs
• Hotel Gyms
• Personal Training Studios
• Sports Performance Facilities
• Physical Therapy Clinics
• Rehabilitation Centers

Recommended Training Goals:

• Muscle Growth (Hypertrophy)
• Strength Development
• Sports Conditioning
• Injury Prevention
• Functional Performance
• Post-Rehabilitation Strengthening

Ergonomic Advantages

• Anatomically aligned pivot points
• Reduced joint stress
• Comfortable seated posture
• Adjustable starting positions
• Smooth and controlled movement path
• Easy machine transitions between exercises

The ergonomic design accommodates users of different heights while maintaining correct biomechanics and exercise efficiency.

Specifications

Specification	Details
Model	SGDS-72
Exercise Functions	Seated Leg Curl / Leg Extension
Frame Material	50 × 100 mm Steel Tube
Tube Thickness	3 mm
Cable Diameter	6 mm
Pulley Material	High-Strength Nylon
Weight Stack Material	Steel
Cushion Color	Black
Finish	Double Powder Coating
Length	1420 mm
Width	1270 mm
Height	1600 mm
Machine Weight	290 kg