Machine Seated Extension

Start Position
End Position

Starting position:

  1. Select the weight you would like to lift and insert the pin into the designated hole of the plate stack.
  2. Adjust the seat height so your upper arms and elbows are rested on the pad just below shoulder level.
  3. From a seated position, grab the handles with a neutral grip (palms facing each other) and bent elbows.
  4. Sit straight up with feet flat on the floor.

Downward movement/concentric phase:

  1. Extend elbows, pushing the handles downward, straightening arms across pad.
  2. Maintain good posture, sitting straight up throughout the entire movement.

Upward movement/eccentric phase:

    1. In a controlled fashion, allow the elbows to bend, returning the handles back to starting position.
Do not hold your breath. Exhale during the concentric/phase phase and inhale during the eccentric/lowering phase.


Exercise Data

  • Primary Muscles: Triceps brachii
  • Synergists: Anconeus
  • Stabilizers: Deltoids
  • Type: Strength, hypertrophy, muscular endurance
  • Mechanics: Elbow extension
  • Equipment: Triceps extension machine
  • Lever: 1st class lever
  • Level: Beginner to advanced
  • FAQ'S & FACTS ABOUT Machine Seated Extension

    What Is A Triceps Machine Seated Extension?

    Seated triceps extensions on a machine involve the primary elbow extensor, the triceps brachii. The upper arms are rested against pads, preventing the movement of the shoulders while isolating the triceps. The resistance is provided by a pulley system with which you adjust the weight accordingly with a pin. This makes it easy for the lifter to manipulate the load they are lifting without having to rack bars and plates.

    This exercise is performed seated, mimicking the movement executed with other triceps extension free-weight exercises. Unlike free-weight triceps exercises, however, the pulley system provides a uniform resistance throughout the entire range of motion.

    The concentric portion of the lift is elbow extension, which involves the lifting of the weight. The eccentric portion is elbow flexion, which involves the descent of the weight.

    The purpose of the seated triceps extension machine is to strengthen the triceps while promoting hypertrophy (increases in size) of triceps.

    Why Do Triceps Machine Seated Extensions?

    Seated triceps extensions on a machine provide a variation in exercises that activate the triceps brachii. It is a seated variation of triceps extensions, which allows the lifter to rest their upper arms on a pad. This position allows the lifter to perform the exercise with stricter technique, isolating elbow extension more effectively compared to the other triceps exercises.

    The positioning of the arms places emphasis on the long and medial heads of the triceps with elbow extension. The long head of the triceps is the only one of the three triceps heads that crosses the shoulder joint, attaching at the scapula. Therefore, performing elbow extensions with the upward positioning of the arms places greater stress on the long head. The long head of the triceps makes up the top and inner portions of the “horseshoe”. Building the medial and long heads of the triceps complements overall aesthetics of the triceps muscle.

    Performing elbow extensions on machines allows novice lifters to learn and develop triceps activation and strength. Intermediate and advanced lifters can benefit from implementing machine triceps extensions into their regimen as machines can provide a variation in angle, grip and resistance. Although it is primarily an exercise for aesthetics, machine triceps extensions also serve as an auxiliary exercise that can increase strength involved in other multi-joint exercises.

    Overall, seated triceps extensions on a machine strengthen and increase the size of the triceps brachii. They also serve as an auxiliary exercise that can increase strength involved in other multi-joint exercises.

    Anatomy Of A Triceps Machine Seated Extension

    The triceps brachii is located on the back of the upper arm, originating at the shoulder and inserting in the elbow joint. It consists of three heads, the long, medial and lateral head. The medial head lies beneath the long and lateral head. The long head origin is located at the infraglenoid tubercle of the scapula (shoulder blade). The original of the lateral head is located at the posterior shaft of the humerus. The medial head origin is located at the radial groove of the posterior humeral shaft.

    The long and lateral heads make up the “horseshoe” portion of the triceps. All three heads merge, sharing insertion into the olecranon process of the ulna, located at the elbow joint.

    The triceps brachii extend the elbow joint. The long head assists in arm adduction.

    The anconeus is a short, triangular muscle located at the elbow joint. Its origin is located at the lateral epicondyle of the humerus, inserting at the lateral aspect of the olecranon process of the ulna.

    The positioning of the shoulders in a flexed position requires the deltoids and rotator cuff muscles to ensure stability of the joint capsule throughout the movement.

    Variations Of A Triceps Machine Seated Extension

    One-arm machine triceps extensions.

    How To Improve Your Triceps Machine Seated Extensions

    Focus on the concentric portion of the contraction, concentrating on “squeezing” at the end of the flexing portion.

    Emphasis on eccentric contractions, prolonging the eccentric portion of the contraction, may also be incorporated in a training program focused on increasing strength. This should be implemented accordingly and with adequate muscle recovery as eccentric contractions cause substantial damage to muscle tissue.

    It’s important to note that your repetition and set volume will depend on your goals (e.g. strength, hypertrophy, muscular endurance). It is also important to allow adequate recovery days in between triceps and chest training to allow muscles to repair.

    Common Mistakes When Doing Triceps Machine Seated Extensions

    Returning the weight to starting position too quickly can threaten joint and tendon integrity. Performing the eccentric portion of the lift ballistically (e.g. dropping the weight on the way down) can result in triceps tendon and/or elbow injuries.

    It is important to note that exercise machines, in general, may not accommodate ergonomically to the varying heights, torso lengths and limb lengths of individuals. Adjust the seat height accordingly and ensure that you do not place your joints in any compromising positions against the weighted resistance.

    Injuries Or Ailments & Their Effects Regarding Triceps Machine Seated Extensions

    If proper technique is not adhered to (e.g. dropping the weight quickly instead of controlling the descent on the eccentric portion of the lift, lifting a load too heavy for the lifter), the likelihood of injury increases.

    Although rare, triceps tendon rupture and/or injury may occur if warm-up is not sufficient and/or if intensity (load) is increased inappropriately.