ZULTA
NL Join the waitlist

Hamstrings

Razor Curl

The Razor Curl is a strength exercise with no equipment for your hamstrings. Share of the load in the Zulta muscle model: hamstrings (semitendinosus/-membranosus) 44%, hamstrings (biceps femoris) 30% and calves (gastrocnemius) 10%.

Level: AdvancedEquipment: BodyweightSingle-joint (isolation)

How to do it

  1. Kneel on a pad or GHD with your ankles locked in place and your body upright.
  2. Lean forward from the knees, keeping a straight line from knees to head, until the torso is close to horizontal.
  3. Bend at the hips as you near the bottom so the torso folds down toward the thighs.
  4. Curl back up by bending the knees while opening the hips again, reversing the path.
  5. Finish upright with the hips fully extended.

Tips

  • Think of it as a Nordic Curl on the way down and a hip hinge that lets you back up.
  • Move smoothly between the two phases rather than stopping at the switch.

Common mistakes

  • Folding at the hips too early so the hamstrings never work at the knee.
  • Arching the lower back when the hips reopen.
  • Rushing the lowering phase.

Muscles worked by the Razor Curl

  • Hamstrings (semitendinosus/-membranosus) Primary44%
  • Hamstrings (biceps femoris) Primary30%
  • Calves (gastrocnemius) Secondary10%
  • Gluteus maximus Minor6%
  • Adductors Stabilizer4%
  • Spinal erectors (lower back) Stabilizer4%
  • Upper abs Stabilizer2%

Share per muscle in the Zulta muscle model. The model spreads the load of one rep over 40 muscles, based on EMG and biomechanics research.

The body lowered against the hamstrings; Nordics bias semitendinosus (Bourne 2017). Knee flexion with the thigh fixed isolates the hamstrings, with gastrocnemius assisting; a flexed hip (seated) lengthens the hamstrings and grew them more than lying curls.

Razor Curl alternatives

Same equipment

Different equipment

Easier

Make it easier

Similar exercises

Frequently asked questions

What muscles does the Razor Curl work?

Mainly the hamstrings (semitendinosus/-membranosus) and hamstrings (biceps femoris). The calves (gastrocnemius) assist.

Is the Razor Curl good for beginners?

The Razor Curl is rated advanced. If you are new, learn the Banded Nordic Curl first and build up from there.

What is a good alternative to the Razor Curl?

For example the Banded Nordic Curl, Glute Ham Developer Raise and Natural Leg Curl. They train mostly the same muscles, some with different equipment.

Sources

  • Maeo et al. 2021, MSSE 53(4):825-837 (seated vs prone leg curl)
  • Bourne et al. 2017, Br J Sports Med 51(13):1021-1028 (Nordic curl biases semitendinosus)

Log your sets in Zulta

Zulta tracks your sets, weights and muscle load next to your running, riding or Hyrox training. The app opens soon.

Join the waitlist