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Knee to Elbow Touch to Star Crunches

This combo alternates the compact diagonal knee-to-elbow touch with a full star position — arms and leg flung wide — so the obliques fold and then fully lengthen on every cycle. It suits trainees who want standing core work with a bigger range and balance demand than simple touches provide. Coached by Maddy (NASM-CPT) — these are the exact form cues he gives on every client's first week.

Muscles worked

Obliques Abs · rectus abdominis Deep core · transverse abdominis

Sets & reps by goal

GoalSets × RepsRest
Strength4 × 5–6 cycles per side (slow)90 s
Muscle3–4 × 8–12 cycles per side60–90 s
Endurance3 × 15–20 cycles alternating45–60 s

Rep ranges per Helms 2014 · Schoenfeld 2016.

Level — Beginner

Beginner with a built-in dial — the wider the star and the longer the balance, the harder it gets.

Proper form — 5 cues

  1. Perform the knee-to-elbow touch first: opposite elbow folding down to the rising knee.
  2. From the touch, explode open — the same leg sweeps out wide as both arms reach up and out into a star.
  3. Hold the open star for a beat, tall and stretched, before folding into the next touch.
  4. Keep the standing leg's knee soft through both phases; it is working the whole time.
  5. Complete all reps on one side before switching, or alternate — just decide before the set.

Breathing: Exhale into the fold, inhale as the body opens wide into the star.

The 3 mistakes Maddy corrects most

Blurring the fold and the star into one motion. Neither position is ever fully reached, so the obliques never get their full shorten-lengthen cycle. Fix: Treat it as two photographs per rep — full fold, full star — with movement in between.
Tipping over during the open position. Flinging the limbs wide without a braced trunk turns the star into a stumble. Fix: Shrink the star's size until balance is reliable, then expand it gradually.
Letting the arms go soft and vague. Loose arms shrink the stretch across the waist that makes the open phase worthwhile. Fix: Reach actively through the fingertips in the star, as if pushing two walls apart.

Common questions

What does the star add over plain knee-to-elbow touches?

Range and balance. The plain touch works the obliques in their shortened half; the star drives the same tissue through a full stretch while you balance on one leg with limbs extended. That shorten-to-lengthen cycle per rep is a more complete stimulus, and the balance element trains stability for free.

Is this too hard for a beginner?

It is filed as beginner-accessible because every element scales: make the star smaller, touch the toe down between phases, or slow everything to a stately tempo. The full flung-wide version with a hovering leg is genuinely challenging, so treat the size of the star as your difficulty dial.

Should I feel this in my standing leg?

Yes — the standing side's glute and thigh stabilise every fold and every opening, and they often tire before the waist does. That is a feature: the drill quietly trains single-leg stability alongside the obliques. Switch sides when the standing leg starts wobbling rather than pushing into sloppy reps.

Related exercises

Easier: Knee to Elbow Touch

Bicycle KicksObliques Bicycle Kicks (Modified)Obliques Cross Knee to Elbow PulseObliques Downward Dog Cross Knee to Elbow TouchObliques Downward Dog Knee to Elbow TouchObliques

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