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The Hundred on the Reformer: How to Do It and Muscles Worked

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The Hundred on the Reformer is an intermediate Pilates exercise that takes a familiar mat movement and adds the challenge of strap resistance. By holding the reformer straps while pumping your arms, you create a dynamic tension that requires steady control.

This movement focuses heavily on your rectus abdominis and transversus abdominis as you hold your spine in flexion. The added resistance from the straps also recruits your shoulder extensors, making your upper body work harder to maintain a stable carriage while your legs hover in the air.

Exercise data

Type
Reformer
Level
Intermediate
Equipment
Reformer
Main muscles
rectus abdominis, transversus abdominis
Also working
shoulder extensors
Spine
spinal flexion
Focus
The hundred with straps adding arm resistance
Also searched as
hundred reformer, reformer hundreds

How to do The Hundred on the Reformer

Lie on your back on the reformer carriage with your knees bent in a tabletop position and your hands holding the straps directly above your shoulders.

  1. Exhale and nod your chin to curl your head and upper shoulders off the carriage into spinal flexion.
  2. Simultaneously press your arms down toward the carriage until they are straight and hovering just above your hips.
  3. Extend your legs straight out to a challenging but comfortable angle where your lower back feels supported.
  4. Vigorously pump your arms up and down a few inches while keeping the rest of your body completely still.
  5. Continue pumping your arms in rhythm with your breathing pattern.
  6. Once you finish your breath cycles, bend your knees back into tabletop.
  7. Lower your head and arms back to the starting position with control.
  • Breath. Teachers cue breathing differently, but a common pattern is to inhale for five arm pumps and exhale for five arm pumps. Focus on breathing wide into your ribs to keep your abdominal muscles engaged throughout the exercise.
  • Where you feel it. You should feel a deep, continuous burn in your rectus abdominis and transversus abdominis, along with work in the back of your arms and shoulders. You should not feel tension in your neck or a pinching sensation in your lower back.
  • How many. 10 full breath cycles, totaling 100 arm pumps

Common mistakes

  • Dropping the legs too low. Keep your legs high enough so that your lower back does not arch away from the carriage.
  • Moving the carriage. Your arm pumps should be sharp and isolated, keeping the carriage as still as possible.
  • Straining the neck. Make sure your spinal flexion comes from your abdominal muscles rather than pulling your chin forcefully into your chest.
  • Bending the wrists. Keep your wrists straight and strong as you press into the straps to properly engage your shoulder extensors.

Make it easier or harder

Easier

  • Keep your knees bent in a tabletop position instead of extending your legs straight.
  • Rest your head on the headrest and focus only on the arm pumps and breathing.
  • Use a lighter spring setting to reduce the resistance on the straps.

Harder

  • Lower your extended legs closer to the footbar while maintaining your spinal flexion.
  • Use a slightly heavier spring setting to challenge your shoulder extensors and core stability.

Who should be careful

  • If you have osteoporosis or low bone density, or a recent disc injury, ask your clinician whether repeated loaded forward bending of the spine suits you. Many bone health organizations recommend limiting it.
  • Lifting the head for a long time can strain the neck. Rest the head on the mat or support it with one hand when the neck tires.
  • After the first trimester of pregnancy, many guidelines advise against long periods lying flat on the back. A side-lying or propped version is an alternative.
  • Reformer springs and the moving carriage add load and instability. Learn it with a qualified instructor, who can set the springs for your body and goals.

Related exercises

When to see a doctor or physical therapist

  • Sharp pain in your lower back when extending your legs.
  • Severe neck pain or a feeling of strain that does not go away when you rest your head.
  • A pulling sensation or pain in your shoulder joints.

This page is general education, not a diagnosis or treatment plan. If you have a health condition, are pregnant or are recovering from an injury or surgery, check with your own clinician before trying new exercises.

How we put this page together. Exercise data (type, level, equipment and muscles) was compiled by our editors from the classical mat order in Joseph Pilates’ 1945 book and from commonly taught reformer repertoire. Muscle lists are a general anatomy guide; cueing differs between teachers. Text drafted with AI assistance and checked by the Editorial Team. See our editorial policy. Last checked October 2026.