How to Do Spider Planks: Proper Form, Common Mistakes, and Progressions

Spider planks look like a small change to a standard plank, but the knee coming out to the side changes the job of your core. Instead of only holding your body straight, your trunk has to keep your hips from twisting while one knee comes up and out toward the elbow. That is why you feel spider planks along the sides of your waist.

Keep your hips from twisting toward the moving knee, sagging toward the floor or piking toward the ceiling. If they sag or twist, lower to the floor and rest, then restart with a shorter knee path. A smaller knee drive with level hips is the right place to start.

Muscles Worked

Primary muscles: the obliques and the hip flexors. The obliques, along the sides of your waist, bend your trunk toward the knee and keep your hips from twisting. The hip flexors, at the front of the hip, lift the knee up and out toward the elbow.

Secondary muscles: the rectus abdominis and the transverse abdominis. The rectus abdominis, on the front of your belly, holds the plank so your hips don't sag. The transverse abdominis, the deep belly muscle that wraps around your trunk, braces it while the leg moves.

Keeping your hips level: as one knee comes up and out, your hips can twist open or sag. Your obliques and the rest of your abs keep them low, level and facing the floor. A slight tilt as the knee comes up is fine, but a twist is not. A shorter knee path is the fix.

Step-by-Step: How to Perform Spider Planks

Step 1: Start in a forearm plank

Place your forearms on the floor with your elbows directly under your shoulders and your hands in loose fists. Extend your legs behind you, feet together or about hip-width apart on your toes. Brace your abs and make a straight line from head to heels, hips neither sagging nor raised.

Form tip: use a mat or folded towel under your forearms, and keep your head in line with your spine, eyes on the floor just ahead of your hands.

Step 2: Bring one knee toward the same elbow

Lift one foot and bring that knee out to the side and forward toward the outside of the same elbow. The knee travels out to the side, not straight under your chest like a mountain climber.

Form tip: the knee does not have to touch your elbow. Get it as close as you can while your hips stay low and level.

Step 3: Pause without letting the hips turn

Pause briefly with the knee as close to your elbow as you can get it. Keep both hips low and facing the floor; a slight tilt is fine, but don't let them twist open, pike up or sag.

Form tip: if your hips twist, lower to the floor and rest, then bring the knee a shorter way.

Step 4: Return to plank and switch sides

Take the leg back with control until the foot is on the floor beside the other one, keeping the moving foot off the floor until then. Then bring the other knee toward the other elbow the same slow, controlled way.

Form tip: alternate every rep, with the same pace on both sides.

Step 5: Breathe and keep the tempo controlled

Breathe out as your knee comes forward and in as it goes back, or just breathe steadily in your own rhythm, and never hold your breath. Take about two seconds per side and move slowly enough that your hips stay level on every rep.

Form tip: keep breathing steadily for the whole set.

Common Mistakes (and How to Fix Them)

• Letting the hips rotate. The pelvis rolls toward the moving knee and your trunk twists. A slight tilt is fine, but a twist is not. If your hips twist, lower to the floor and rest, then restart with a shorter knee path that keeps both hips facing the floor.
• Piking the hips up. Raising the hips breaks the straight line from your head to your heels. Brace your abs and lower your hips until your body forms one line again.
• Sagging through the lower back. Your hips and lower back drop toward the floor and break the straight line from your head to your heels. Lower to the floor and rest, then restart with a shorter knee path, or hold a still forearm plank to build up.
• Rushing the knee drive. Moving fast makes it easy to miss your hips twisting. Bring the knee out, pause briefly, then take it back with control, about two seconds per side.
• Elbows drifting from under the shoulders. If your elbows creep forward or back, your shoulders are no longer stacked over them. Keep your elbows right under your shoulders for the whole set.
• Letting the head hang or craning it up. Either one pulls your neck out of line with your back. Keep your head in line with your spine, eyes on the floor just ahead of your hands.
• Holding your breath. It is easy to stop breathing while you hold the plank. Breathe out as your knee comes forward and in as it goes back, or breathe steadily in your own rhythm.

Spider Plank Variations: Easier and Harder Versions

Still Forearm Plank or Shorter Knee Path

Hold the forearm plank still, legs straight, without moving your knees. When that feels steady, bring each knee only partway out and rest a moment between sides. This lets you learn to keep your hips level before the full knee path.

Standard Spider Plank

This is the full version: forearm plank, alternating knee drives out toward the same elbow, slow tempo, and level hips. Get comfortable with this version before you try the slower or paused reps.

Paused Spider Plank

Hold your knee beside your elbow for about two seconds each side, or slow the whole move down, taking the knee out slowly and bringing it back just as slowly. Your hips have to stay low and level for longer on each side, which makes it the harder version.

Spider Plank on Your Hands

You can also do the same knee drive from a high plank on your hands, with your hands under your shoulders and your arms straight. It is a valid way to do the exercise; this guide and the FitCraft app use the forearms.

Alternative Exercises

• Mountain Climbers: drive the knee forward under your chest from a high plank, at a faster pace. The FitCraft app rates them Expert, harder than the Advanced spider plank.
• Bicycle Crunches: lie on your back and turn your trunk to bring each elbow toward the opposite knee, with no plank to hold.

When to Avoid Spider Planks

Spider planks are an advanced exercise. If any of the situations below applies to you, check with a doctor or physical therapist before you do them. A burn along your waist, belly or the front of your hip is normal. Any pain in a joint, your lower back, your neck or your shoulders means stop the exercise and see a doctor or physical therapist before you try it again.

• Acute lower-back pain or a known disc problem. See a doctor or physical therapist before you do spider planks, and do them only once they clear you. During a set, any pain in your lower back means stop the exercise.
• After giving birth, or diastasis recti. Get clearance from your doctor or a pelvic-floor physical therapist before you do spider planks, especially after a C-section. Stop and check with them if you see coning or doming along the middle of your belly, or if you feel any pain.
• Recent abdominal surgery, a hernia or a hernia repair. Get clearance from your surgeon or doctor before you do spider planks, do them only once they clear you, and stop if you feel any pain.
• Wrist, elbow, or shoulder pain. On the forearms your elbows and shoulders hold your weight, and the version on your hands adds your wrists. If any of these joints hurts, see a doctor or physical therapist before you do spider planks, do them only once they clear you, and stop if you feel any pain in a wrist, elbow or shoulder.
• Pregnancy, pelvic-floor dysfunction, or pelvic-organ prolapse. Check with your doctor, midwife or a pelvic-floor physical therapist before you do spider planks, and do them only with their go-ahead. Stop if you feel pelvic pressure or any pain.

Related Exercises

If spider planks fit your routine, these exercises train your core in related ways:

• Other moving core exercises: Plank Walks keep your hips level while you move from your forearms to your hands, and Plank Twists turn your chest and hips open to each side on purpose from your hands and toes.
• Easier trunk control: Deadbugs on your back and Bird-Dogs on your hands and knees train a steady trunk without holding a plank.
• Still planks: Forearm Planks are the still, easier version of this exercise, and Hand Planks hold the high plank that the version on your hands starts from.

How to Program Spider Planks

Spider planks are rep-based core stability work, so build volume gradually and stop each set when the plank position breaks. The American College of Sports Medicine Position Stand on resistance training supports progressive volume, appropriate rest, and level-based loading for healthy adults (Ratamess et al., 2009). The table below gives practical starting ranges for each level.

Where in your workout: do spider planks near the end of a session or in a short core block, after your main exercises.

Stop when your form breaks: if your hips twist, sag or pike during the last reps, end the set there.

How FitCraft Programs This Exercise

FitCraft maps your fitness level, goals, and available equipment, then builds a balanced training plan for your level. The app has one spider plank, on the forearms with the knees alternating, rated Advanced, with a 3D demonstration. It also has the forearm plank, the still version you can build up from.

Every FitCraft program is designed by Domenic Angelino, MPH (Brown University) and NSCA-CSCS, with research published in the Journal of Strength and Conditioning Research and Medicine & Science in Sports & Exercise.