Plank: Muscles Worked and How to Do It
TL;DR
A plank works your abs as the prime mover: your rectus abdominis and obliques brace to hold your spine in a straight line while your deep transverse abdominis stabilizes from underneath. Because it's a hold rather than a rep, it trains your abs for endurance and control instead of pure strength.
- Primary muscle:
- Abdominals
Muscles worked
The plank is an isometric hold, meaning your abs work by resisting movement rather than creating it. Your rectus abdominis (the visible 'six-pack' muscle) and your obliques on the sides of your waist contract to stop your hips from sagging or piking, while your deeper transverse abdominis acts like a corset, bracing your spine from the inside. Together they train your core to stay rigid under load, a skill that carries over to squats, deadlifts and overhead presses.
Log Plank in PR Streak
PR Streak's library has 873 exercises, each with photos and step-by-step instructions like this one. Log this move and see what you lifted last time right next to every set, with every PR caught automatically and a chart for every exercise.
How to do it
- Get into a prone position on the floor, supporting your weight on your toes and your forearms. Your arms are bent and directly below the shoulder.
- Keep your body straight at all times, and hold this position as long as possible. To increase difficulty, an arm or leg can be raised.
Form tips
- Stack your elbows directly under your shoulders and squeeze your forearms into the floor.
- Keep a straight line from your head to your heels: don't let your hips sag or pike up.
- Squeeze your glutes and quads to help lock your pelvis in place.
- Breathe steadily through the hold instead of holding your breath.
- Look at a spot on the floor a few inches ahead to keep your neck neutral.
Exercise details
| Equipment | Bodyweight |
|---|---|
| Level | Beginner |
| Mechanic | Isolation |
Used by lifters following PPL, 5x5, upper/lower, and more.
Frequently Asked Questions
Does the plank work more than just abs?
The plank is classified as an abs exercise because your abdominals do almost all of the work of keeping your spine straight. Your shoulders and glutes help hold the position, but they're stabilizers rather than prime movers, so the training effect is centered on your core.
How is a plank different from crunches?
A crunch moves your spine through a range of motion to shorten your abs, training strength in that range. A plank holds your spine still while your abs resist movement, training endurance and stability instead. Many lifters use both: crunches for targeted work, planks for core control under a hold.
Can planks replace core training for lifting?
Planks build the bracing strength that keeps your spine stable during squats and deadlifts, which makes them a solid foundation. Pairing them with loaded core work, like ab wheel rollouts, adds overload that a bodyweight hold alone can't provide.
More abdominals exercises
Exercise instructions and photos come from the free-exercise-db library, public domain, the same library used inside the PR Streak app.
