The plank is a popular exercise. As well as being an excellent general abs strengthener, it also teaches you how to brace your core and stabilize your lumbar spine. Bracing is critical for the correct and safe performance of most strength training and cardio exercises because it’s what prevents unwanted movement of your lower back.
However, as effective as the plank is, it’s one of those exercises that can soon become too easy to be beneficial. After all, once you can plank for a minute or two, it’s not going to do much for your core strength, and planking for longer is not an efficient use of your workout time.
While this may mean you’re tempted to drop the plank from your workouts, there are ways to make it effective again, such as the plank knee to elbow exercise.
In this article, we reveal why and how to do planks knee to elbows, plus several similarly effective alternatives and variations.
Plank Knee to Elbow – Muscles Worked
The plank knee to elbow exercise works all of your core muscles. Core is the collective term for the muscles of your midsection. The main muscles trained during this exercise are:
Rectus abdominis – located on the front of your abdomen and known as the abs for short, this muscle flexes your spine. Also, it plays a part in spinal lateral flexion. In plank knee to elbows, it stops your spine from extending, working isometrically or statically. When well-developed, and if you are lean enough, this is the muscle that gives you a six-pack.
Obliques – the obliques are your waist muscles. There are two sets of obliques; internal and external. The obliques usually rotate your spine, but during plank knees to elbow, they prevent your hips from twisting as you perform the movement.
Transverse abdominis – while you can’t see your TVA, it’s still a significant muscle. Encircling your waist like a weightlifting belt, it compresses the contents of your abdomen to create intra-abdominal pressure to support your spine. While most people feel knee to elbow planks in their abs, it’s the TVA that’s doing most of the work.
Erector spinae – the erector spinae are the muscles of your lower back. While they aren’t involved directly in plank knee to elbows, they work with the other core muscles to help keep your lumbar spine stationary.
In addition to these core muscles, plank knee to elbows also involve several upper and lower body muscles. They work to hold you in the elevated or high plank position. This means the plank knee to elbow is virtually a full-body exercise.
These lesser muscles include:
- Pectoralis major – chest muscles
- Deltoids – shoulder muscles
- Triceps – rear of the upper arm
- Serratus anterior – side chest/upper outer abs muscles
- Quadriceps – front of the thigh
How to Do Plank Knee to Elbow
Get more from plank knee to elbows while keeping your risk of injury to a minimum by following these guidelines:
- Adopt the push-up position with your arms and legs straight. Your knees, hips, and shoulders should form a line. Look straight down at the floor, pull your shoulders down and back, and brace your core. Tense your quadriceps and glutes.
- Bend one leg and draw your knee up to the outside of your elbow and touch it lightly. Do not lean to the side or twist your hips or shoulders.
- Extend your leg and return to the starting position.
- Repeat the movement on the opposite side.
- Continue alternating legs for the prescribed duration or number of reps.
- Keep your movements slow and smooth throughout.
Plank Knee to Elbow Benefits and Drawbacks
Not sure if the plank knee to elbow is the best exercise for your core workouts? Consider these benefits…
A more challenging way to plank – if you can hold a regular plank for more than a couple of minutes, it could be that you are wasting a lot of workout time on a pointless exercise. Plank knee to elbows are a more demanding exercise and an excellent way to increase core strength without spending more time planking.
Increased oblique engagement – while your oblique or waist muscles are involved in regular planks, they don’t have a lot of work to do. But, during the knee to elbow variation, the obliques have to work much harder to stabilize your spine. As such, plank knee to elbows are a much more complete core exercise.
No need to time yourself – regular planks are done for time, which means you need to keep an eye on your watch or a clock when you’re doing them. Plank knee to elbows can be done for reps, which may be more practical as you don’t have to keep track of the time.
More upper body engagement – holding yourself up on straight arms during the plank knee to elbow exercise provides your upper body with a small but worthwhile workout. You may feel this exercise in your triceps, chest, and shoulders, as well as your core.
Teaches you how to stabilize your spine while moving your legs – planks are a very stationary exercise. Still, you also need to be able to stabilize your core during more dynamic movements, such as walking, running, jumping, and lifting. Plank knee to elbows teaches you how to stabilize your spine during movement.
While plank knee to elbows are a mostly beneficial exercise, there are also a few drawbacks to consider:
Arm fatigue – if you don’t have strong arms, you may find your triceps fatiguing before your abs. One way around this problem is to do plank knee to elbows with your forearms resting on a bench.
Limited overload – while plank knee to elbows are most definitely more challenging than regular planks, they’re still a relatively straightforward, easy exercise. So, after a few months of doing them regularly, you may well find that they are no longer hard enough to be of much benefit.
Don’t worry, though, as there are plenty of more challenging exercises you can do, as described below.
7 Plank Knee to Elbow Variations and Alternatives
Plank knee to elbows are an effective core exercise. Still, they’ll gradually start to become less effective as your core gets stronger. The good news is that there are several variations and alternatives you can use to keep your core workouts productive and interesting:
1. Stability ball plank knee to elbow
Also known as stability ball mountain climbers, this exercise increases the demands on your core by introducing more instability. In short, as the ball moves, you’ll need to brace even harder to prevent unwanted movement. And yes, your abs SHOULD shake like that when you’re doing this exercise!
How to do it:
- Rest your forearms on the ball, and then walk your feet back and into the plank position. Brace your core.
- Bend one leg and pull your knee up to touch your elbow.
- Extend your leg and return to the starting position.
- Swap sides and repeat.
2. Spider-man push-ups
The Spider-man push-up is so-called because, when viewed from above, it looks a little like you are crawling up a wall, just like superhero Spider-man can. This exercise combines the knee to elbow plank with push-ups to increase upper body engagement.
How to do it:
- Adopt the standard push-up position with your hands roughly shoulder-width apart, legs and arms straight. Brace your abs and pull your shoulders down and back.
- Bend your arms and lower your chest down to within an inch of the floor.
- Simultaneously bend one leg and pull your knee out and up to touch your elbow.
- Extend your arms and leg, swap sides, and repeat.
3. Renegade row
Where plank knee to elbows involve doing planks while lifting your legs, renegade rows involve doing planks while lifting your arms. Because you can do renegade rows with dumbbells, you can make them easier or harder by adjusting the weights. Like plank knee to elbows, this exercise increases oblique engagement.
How to do it:
- Hold a dumbbell in each hand. You can also use kettlebells.
- Squat down and place the weights on the floor, roughly shoulder-width apart.
- Brace your abs and walk your feet out and back into the push-up position. Your body should form a straight line. Keep your wrists straight, and do not allow them to collapse.
- Move your feet out so that they are wider than shoulder-width apart to increase balance and stability. Look straight down at the floor to ensure your neck is neutral.
- Keeping one arm straight, bend the other arm and row the weight up and into your lower ribs. Do NOT allow your hips or shoulders to twist.
- Lower the weight back to the floor, swap sides, and repeat. Alternate arms for the duration of your set, keeping your core braced throughout.
- You can also do this exercise with your legs bent and knees resting on the floor to take pressure off your core.
Read more about renegade rows in our in-depth guide.
4. Bear crawl
Bear crawls are a logical progression after plank knee to elbows. With this exercise, instead of just moving your legs, you move your arms too, so you travel forward in a semi-plank position. This increases both core and upper body engagement and also produces a better conditioning workout.
How to do it:
- Kneel down on all fours so your hands are directly under your shoulders and your knees are under your hips. Pull your toes up and press the balls of your feet into the floor.
- Brace your abs, pull your shoulders down and back, and rotate your elbows inward to engage your lats. Your lower back and neck should be neutral. Lift your knees a few inches off the floor while keeping your hips level with your shoulders.
- Without lifting your hips, move your left hand and right foot forward, and then your right hand and left foot.
- Continue crawling forward over the specified distance or number of steps.
- You can also bear crawl backward, sideways, and diagonally.
You can read more about bear crawls here.
5. Walkouts
Walkouts are a challenging core exercise. With this exercise, you walk your hands out along the floor to put yourself in an extended plank position. This works the same muscles as plank knee to elbows. But, because of the greater distance between your hands and feet, there is more weight on your core muscles.
How to do it:
- Stand with your feet together, arms by your sides. Brace your abs.
- Hinging from your hips, lean forward and place your hands on the floor. Depending on your hamstring flexibility, you may need to bend your knees a little (or a lot!) to do this.
- Taking small steps, walk your hands forward as far as you can while maintaining your core stability. Do not let your hips drop or hyperextend your lumbar spine. Brace those abs! The further you walk your hands beyond your shoulders, the harder this exercise becomes. Hold this furthest point for a couple of seconds.
- Without relaxing your core, walk your hands back toward your feet and stand up. If you prefer, you can keep your hands on the floor and then transition immediately into another rep.
6. Alternating T-plank
Just like plank knee to elbow, this variation increases oblique or waist engagement as well as working your rectus abdominus. Balancing on one arm will also improve shoulder and triceps strength. The side-to-side motion of this exercise allows you to really overload your obliques, one side at a time.
How to do it:
- Adopt the push-up position. Your arms should be straight with your hands pointing forward and roughly shoulder-width apart. Brace your abs and pull your shoulders down and back.
- Shift your weight onto one arm and rotate your shoulders and hips. Extend your non-weight-bearing arm up to the ceiling to form a T-shape.
- Return your hands to the floor, swap arms, and repeat on the other side.
- Continue alternating sides for the prescribed duration.
7. Pallof press
Invented and named after physical therapist John Pallof, the Pallof press builds core strength and is an excellent way to improve lumbar spine stability. Like plank knee to elbow, you’ll probably feel this exercise in your obliques.
You can do Pallof presses using a cable machine or resistance bands. They can also be done standing, seated, or kneeling for variety.
Learn more about this effective core exercise here.
Plank Knee to Elbow – Wrapping Up
While planks are undeniably popular, they will soon start to lose their effect once you can hold a plank for more than a couple of minutes. Not only are prolonged planks boring, but they’re also ineffective. You don’t do sets of 50-100 reps of curls for your arms, so it makes no sense to do such prolonged sets for your abs.
The most effective way to develop your muscles is to overload them in a reasonable time frame, say 30-60 seconds. That means, for bodyweight exercises, you need to find new ways to make your chosen movements more challenging.
Switching from regular planks to plank knee to elbow is one way to increase the difficulty of your core workout. But, even then, this new exercise will gradually lose its potency as you get stronger.
The good news is that there are plenty of similar but more challenging abs exercises you can use to sculpt the midsection of your dreams, and you’ll find seven of them in this article!
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