What is the antagonist muscle in a leg extension?

When you perform leg extensions, for example, your quadriceps are the active, or agonist, muscles, while the hamstrings are the antagonist muscles, which lengthen while the quads contract.

When performing a leg extension What muscle is the antagonist?

The hamstrings are the agonist and the quadriceps are the antagonist. In the contact and recovery phase, the quadriceps contract to extend the knee while the hamstrings lengthen to allow the movement. The quadriceps are the agonist and the hamstrings are now the antagonist.

Which muscle group is an antagonist to knee extension?

Antagonistic muscle pairs in action

In the contact and recovery phase, the quadriceps contract to extend the knee while the hamstrings lengthen to allow the movement. The quadriceps are the agonist and the hamstrings are now the antagonist.

What are the synergist muscles in a leg extension?

The synergist muscles or those that assist in the exercise and are thus also strengthened are gastrocnemeus in the calf, the sartorius and gracilius in the upper leg and the popliteus or knee flexors.

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What muscles work during leg extension?

Leg extension exercises target the quadriceps femoris. The quadriceps are a group of muscles in the front and side of your thigh.

The muscles worked

  • rectus femoris.
  • vastus lateralis.
  • vastus medialis.
  • vastus intermedius.

What are examples of antagonistic muscles?

Antagonist and agonist muscles often occur in pairs, called antagonistic pairs. As one muscle contracts, the other relaxes. An example of an antagonistic pair is the biceps and triceps; to contract, the triceps relaxes while the biceps contracts to lift the arm.

How do antagonistic muscles work?

One muscle of the pair contracts to move the body part, the other muscle in the pair then contracts to return the body part back to the original position. Muscles that work like this are called antagonistic pairs. In an antagonistic muscle pair as one muscle contracts the other muscle relaxes or lengthens.

What muscles are contracted in knee extension?


Muscle Proximal Attachment Actions
Biceps femoris—long head Ischial tuberosity • Hip extension • Knee flexion • Knee external rotation
Biceps femoris—short head Lateral lip of the linea aspera • Knee flexion • Knee external rotation

What muscles perform knee extension?

The quadriceps femoris muscle group (rectus femoris, vastus lateralis, vastus medius, and vastus intermedius) crosses the knee via the patella and acts to extend the leg.

What type of contraction is knee extension?

A concentric contraction is when a muscle is active while it is shortening under load. Flexing your elbow during a bicep curl and bringing the forearm closer to the shoulder is a concentric contraction for the bicep muscles. If you extend your knee to a straight leg, your quadriceps are concentrically contracting.

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Which muscles are prime movers in knee extension?

Knee Extension:

  • Prime Mover: Quadriceps – vastus lateralis, vastus medialis, vastus intermedius, rectus femoris.
  • Synergists: There are no true synergists of knee extension. …
  • Antagonists: Biceps Femoris, semimembranosus, semitendinosus, popliteus, gastrocnemius, gracilis, sartorius.

What is the prime mover in leg extension?

The hamstring group cross both the hip and knee joints and are the main movers in knee flexion and thigh extension. These three muscles are the biceps femori… This movement requires the use of the knees, which includes tibiofemoral joint and the femoropatellar joint.

What is the function of a synergist and antagonist?

Antagonist: muscles that oppose, or reverse, a particular movement. Synergist: helps prime movers by adding a little extra force to the same movement or by reducing undesirable or unnecessary movements.

Should you go heavy on leg extensions?

The leg extension as an exercise relies on the torque involved in moving the weight, so you don’t need to load the machine up to the max to get benefit. While the quads are extending the knee the weight is resting just on top of the ankle joint. So you can benefit from not using too much weight.

Is the leg extension machine bad?

Drawbacks of the Leg Extension

The leg extension applies constant tension on the anterior cruciate ligament (ACL), so people with ligament injuries should avoid this exercise. The leg extension also increases the risk of lateral patellar deviation, meaning the knee cap can slide right or left unnaturally.

What’s a good weight for leg extensions?

Based on an average weight lifted of 99.9 lbs for all MyFit users we suggest you start at 50% of that weight: Try 50 lbs and aim for 12-15 reps.

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