Windshield Wipers
Lie on your back with your arms out wide and your legs straight up. From there, sweep your legs slowly through a flat arc to one side and just as slowly to the other, like a windshield wiper. The middle of your back stays on the floor.
Windshield wipers are rotational core work done lying on your back. Your legs point straight up, and the sweep out to the side and back is the whole exercise.
The pull comes from the side: as your legs travel one way, the muscles on the other side hold them. That's the job of the muscles that run diagonally and straight across your waist. The muscles down the front of your belly keep your legs up and your trunk long, and your hip flexors carry the weight of your legs.
Your abdominal wall works under tension throughout rather than in short reps. That holding is what you're training.
You progress by changing the lever and widening the arc: bent knees and a small sweep first, straight legs and a wide sweep later.
Starting position
Lie on your back and spread your arms out wide with your palms on the floor. Andreas also grabs a dumbbell in each hand to hold on to, which keeps his upper body steadier.
Lift your legs, keeping them straight, until they point straight up. Your lower back stays in contact with the floor, at least through the middle.
Now sweep your legs through a flat arc to one side, slowly and under control, and back across just as slowly. The rotation comes from your pelvis and hips — your lower back gives very little, which is why the arc stays flat.
Holding your legs straight and vertical takes length in your hamstrings. If your legs drift back or your back lifts, bend your knees a little: same movement, shorter lever.
The three cues
- Keep your back on the floor, at least through the middle
- Legs stay straight
- A flat arc out to the side
- Slow and controlled
Common faults
| Fault | How to fix it |
|---|---|
| The middle of your back lifts off the floor | Make the arc smaller until the middle of your back stays down again. |
| Your knees start to bend on the way across | Your legs stay straight. Once they bend, the set is over. |
| Your legs fall to the side | Guide them slowly and evenly both ways. You set the tempo and you carry the weight of your legs. |
| Your upper body turns with them | Arms out wide, palms pressed into the floor. A dumbbell in each hand gives you more to hold on to. |
| Your legs drift back past vertical | Bend your knees a little until you can hold your legs vertical again. |
Variations
| Variation | When to use it |
|---|---|
| Knees bent, small arc | Knees bent above your hips, keep the sweep small. Move on when the middle of your back stays down the whole way. |
| Legs straight, flat arc | Legs straight and vertical, sweeping as far as you can while your back stays on the floor. |
| Wide arc | Take the arc further out, keeping the same tempo and the same contact with the floor. |
Reps and load
Andreas's tempo: slow out to the side, slow back, the same both ways. The range sets the difficulty — go as far as you can while the middle of your back stays down.
It belongs with the core work at the end of a session. It asks for solid bracing and length in your hamstrings; if you're still building either, work with bent knees first.
Which muscles do the work
| Muscle | Role | What it does here |
|---|---|---|
| External oblique M. obliquus externus abdominis | Prime mover | Slows the turn to the opposite side and brings your legs back |
| Internal oblique M. obliquus internus abdominis | Prime mover | Works crosswise with the external oblique and holds the pelvis |
| Transversus abdominis M. transversus abdominis | Synergist | Wraps around your trunk like a belt and keeps the abdominal wall firm |
| Rectus abdominis M. rectus abdominis | Synergist | Keeps your trunk long and your pelvis in place |
| Hip flexors M. iliopsoas | Synergist | Hold your straight legs up |
| Erector spinae and quadratus lumborum M. erector spinae, M. quadratus lumborum | Stabiliser | Keep your lower back quiet while your pelvis turns |
| Lats and shoulders M. latissimus dorsi, M. deltoideus | Stabiliser | Press your arms into the floor and keep your upper body still |
The obliques do the main work, crosswise: one side leads while the other slows the movement down. The deep belt of muscle around your waist and the front of your abdominal wall keep things firm, and your hip flexors carry your legs. Your arms and shoulders keep your upper body on the floor.
Explained in full
Andreas shows the setup with two dumbbells, the flat arc out to the side, and how you know the set is over. · 2:02
Seeing it done right is not the same as doing it right
Video, cues and variations take you a long way. What they cannot give you is an outside eye at the moment the movement isn't quite there yet. That is what training with me is for — in the studio or in a workshop.
See the workshopsNew exercise pages are added all the time — the newsletter keeps you posted.
Sources
Nakai Y, Kawada M, Miyazaki T, Kiyama R. (2019). Trunk muscle activity during trunk stabilizing exercise with isometric hip rotation using electromyography and ultrasound. J Electromyogr Kinesiol 49:102357. DOI: 10.1016/j.jelekin.2019.102357 — 20 healthy men, lying supine, trunk stabilisation with isometric hip rotation, recorded with surface EMG and ultrasound. The closest work to this exercise's plane of movement and the basis for listing the obliques and transversus in the table. There is no EMG work on the windshield wiper itself, not even the hanging version. Isometric, no leg lever, young men. (Evidence type: EMG)
Pearcy MJ, Tibrewal SB. (1984). Axial rotation and lateral bending in the normal lumbar spine measured by three-dimensional radiography. Spine 9(6):582–587. DOI: 10.1097/00007632-198409000-00008 — Three-dimensional radiographic measurement of rotation per vertebral segment in healthy men: around two degrees per segment. The basis for attributing the turn to the pelvis and hips and for asking for a flat arc. Small group, men only. (Evidence type: Bildgebung in vivo)
Fujii R, Sakaura H, Mukai Y, et al. (2007). Kinematics of the lumbar spine in trunk rotation: in vivo three-dimensional analysis using magnetic resonance imaging. Eur Spine J 16(11):1867–1874. DOI: 10.1007/s00586-007-0373-3 — Ten healthy people, three-dimensional MRI analysis of the lumbar spine at 45 degrees of trunk rotation: 1.2 to 1.7 degrees per segment. It confirms the magnitude found in the older radiographic work, measured lying supine, which is close to this exercise's position. That the rest of the turn comes from the pelvis and hips follows from this rather than being measured directly. (Evidence type: Bildgebung in vivo)
Youdas JW, Krause DA, Hollman JH, Harmsen WS, Laskowski E. (2005). The influence of gender and age on hamstring muscle length in healthy adults. J Orthop Sports Phys Ther 35(4):246–252. DOI: 10.2519/jospt.2005.35.4.246 — 214 healthy adults aged 20 to 79, passive straight-leg raise measured with a goniometer. Women reached further than men, and no age effect showed up. It explains why some people need to start with bent knees. The age range covers the Academy's target group. (Evidence type: Reference data)
Axler CT, McGill SM. (1997). Low back loads over a variety of abdominal exercises: searching for the safest abdominal challenge. Med Sci Sports Exerc 29(6):804–811. DOI: 10.1097/00005768-199706000-00011 — Nine volunteers, twelve abdominal exercises, muscle activity and the resulting lumbar spine load. The core finding: no single abdominal exercise challenges the whole abdominal wall while keeping spinal load low — the longer the leg lever, the higher the load. The basis for progressing this exercise through the lever and for listing bent knees as a stage of its own. The windshield wiper was not among the exercises tested; small sample. (Evidence type: Biomechanics)
Vispute SS, Smith JD, LeCheminant JD, Hurley KS. (2011). The effect of abdominal exercise on abdominal fat. J Strength Cond Res 25(9):2559–2564. DOI: 10.1519/JSC.0b013e3181fb4a46 — 24 sedentary adults, six weeks of abdominal training with diet held steady. Waist circumference, abdominal fat percentage and skinfold thickness were unchanged, while abdominal muscular endurance improved. That is why the page says nothing about waist size or the shape of the belly. It does not support Andreas' statement in the explainer video that the exercise makes the belly flatter. Young sample, short duration. (Evidence type: RCT)
A note on context: EMG studies show which muscles an exercise recruits — that is a good reason to pick it, but it does not replace adjusting things to the person in front of you. See a doctor for persistent or severe pain.