reckonerCable crunch
The cable crunch is the crunch with a weight on it, which matters because the abs answer to load the way every other muscle does. What it asks for is a spine that curls and hips that stay where they are, and nearly everybody gets that the wrong way round.
Round the ribs down to the hips.
- Pattern
- Core flexion
- Trains
- Abs
- Kit
- Cable
- Loading
- A weight you choose
- Reckoner prescribes
- 3 sets of 10 to 15 reps at RPE 8
- Progression step
- 2.5 kg once the top of the range is clean
- Skill
- Some technique
- Recovery cost
- Low
- Not prescribed if you have declared
- Lower back, neck
Muscles worked
How to do it
Kneel under a high pulley
Rope attachment, hands beside your ears or on your forehead, knees a comfortable distance back from the stack so the cable pulls you up and slightly forward. Sit your hips back onto your heels and leave them there.
Curl the ribs toward the hips
The movement is your spine rounding, one segment at a time, from the top down. Your elbows travel toward your thighs because your back rounded, not because your arms pulled.
Finish where the rounding stops
There is a point where the spine has run out of flexion and the only way further is to fold at the hips. Stop there. Going past it adds range you are not training.
Uncurl slowly against the stack
Come back up under control until the spine is long and the abs are stretched, without letting the weight snatch you upright. The way back is where a good part of the work is.
What goes wrong
Hinging at the hips instead of curling the spine
The whole torso swings down like a bow and the weight goes up, so it reads as a good set. What moved was the hip joint, and the abs did almost nothing except hold on.
Pulling with the arms
Hands drift away from the head and the elbows start driving. Now it is a straight-arm pulldown with a crunch attached. Keep the hands glued where they started and the arms out of it.
Going heavier than you can curl
Load is the right idea and it is the first thing to be abused here. When the weight is too heavy the only way to move it is with the hips, so the number goes up and the exercise disappears.
How Reckoner progresses this lift
Six weeks of this lift, from 25 kg, run through the real engine. Nothing below was typed in: the prescription, the decision and the sentence beside it all come from the same code that writes your week.
| Week | Prescribed | What it did |
|---|---|---|
| 1 | 3 x 10 at 25 kg | More reps 10 → 11 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 2 | 3 x 11 at 25 kg | More reps 11 → 12 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 3 | 3 x 12 at 25 kg | More reps 12 → 13 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 4 | 3 x 13 at 25 kg | More reps 13 → 14 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 5 | 3 x 14 at 25 kg | Deload 40% of sets offFive weeks of building, then one week lighter. About 40% of the sets come off. The load holds and your reps stay where you earned them, so you keep the strength and lose the fatigue. |
| 6 | 2 x 14 at 25 kg | More reps 14 → 15 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. The lighter week is over, so this is back to three sets. |
Real engine output, not an illustration. Every row was produced by running the engine itself when this page was generated.
The full rule, and why the reps move before the load does, is in how Reckoner decides to add weight.
Questions people ask
Is a weighted crunch better than a bodyweight one?
It gives you somewhere to go. The plain crunch already sits among the highest exercises measured for both halves of the rectus abdominis and for both obliques, while keeping the hip flexors quieter than a sit-up1. Adding a cable does not change what it trains, it changes how long you can keep making it harder.
How many sets a week should I be doing?
More weekly sets keep buying more size and more strength, with the returns shrinking as the count climbs, and spreading them over more days matters far less for size than the total does2. Reckoner sets the number from your plan and what you logged, so you get an answer on the screen instead of a rule of thumb.
Will this flatten my stomach?
No, and nothing else you do for the abs will either. Six weeks of abdominal training in sedentary adults, food held level, improved abdominal endurance and left body fat, abdominal girth and skinfolds where they were3.
Similar movements
Reckoner eases the load first when this lift stalls, and offers one of these only if it stalls again after that. A lift already as light as your kit goes has no load left to ease, so the offer comes straight away. Each of them has a page.
Sources
- Escamilla and colleagues, Journal of Orthopaedic and Sports Physical Therapy, 2006. An electromyographic analysis of commercial and common abdominal exercises: implications for rehabilitation and training fourteen participants across nine abdominal exercises, with the crunch among the highest for upper and lower rectus abdominis and for both obliques, and with rectus femoris activity greatest in the bent-knee sit-up, which the authors say may be a problem for people with low back pathology
- Pelland and colleagues, Sports Medicine, 2025. The resistance training dose response: meta-regressions exploring the effects of weekly volume and frequency on muscle hypertrophy and strength gains sixty-seven studies and 2058 participants, with size and strength both rising as weekly set volume rises and both showing diminishing returns, and weekly frequency compatible with a negligible effect on size once volume is accounted for
- Vispute and colleagues, Journal of Strength and Conditioning Research, 2011. The effect of abdominal exercise on abdominal fat twenty-four sedentary adults randomized to six weeks of abdominal training or nothing on an isocaloric diet, with no significant effect on body weight, body fat percentage, android fat, abdominal circumference or either skinfold, and a significant improvement in abdominal muscular endurance