The most basic, traditional calf exercise is the calf raise. But even in maximum plantar flexion, my gastrocnemius can be completely relaxed.

I can flex my gastrocnemius, but what movement requires it to contract?

1 Answer 1


The gatrocnemius is part of the triceps surae. This muscle group always co-activates due to how they are innervated and they are the ones that do plantarflexion.

Thus, when you do calf raises to full plantarflexion, there is absolutely no doubt that your gastrocnemius is contracted. The question is how much and which part of it is?

When you do not see the muscle buldging, this probably has two reasons that play a role:

  • the muscle is not loaded enough so that all fibres need to contract: when you're at 30% and below, it is predominantly the (much thinner) Type I muscle fibres doing the work. Thus, there is much less visible contraction. You need resistance putting more weight on that leg.
  • your knee is not fully extended: the more your knee is bent from full extension, the more the soleus does the main part of the work compared to the gastrocnemius. That's because the gastrocnemius has its origin above the knee joint (it is both a plantarflexor and knee flexor in function), so every degree of bending will give it more slack, which makes it harder to tense up under load since origin and insertion are already closer to one another without any effort and the muscle cannot work at its optimal length.

Thus, you need more load and an actively extended knee. This should help to see the gastrocnemius better.

The same goes for training the gastrocnemius for hypertrophy or strength: if you want to target the muscle, fully extend your knees!

  • Turns out it was all about knee extension for me. Even in maximum plantarflexion my gastrocnemius can be completely floppy when my knee is bent. Why is that?
    – minseong
    Commented May 6 at 4:12
  • 1
    @minseong The muscle has its origin above the knee joint, ie with your knee bent, it cannot build tension as well since the proximal end is closer to your heel. Commented May 6 at 4:38

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