Planking is becoming one of the most popular abdominal exercises performed to improve your core strength and stability. The simplicity of it makes it a relatively easy exercise to prescribe and patients or clients can either love or hate the grind that is holding a plank until failure. Previously sit ups were the go to for strengthening your core muscles, but the repetitive flexion and sometimes even flexion & twisting can place a significant load on your lower back specifically your lumbar discs. When planking there are numerous ways to make the exercise harder and likewise ways to make it easier. The perfect plank can increase your abdominal strength and core stability greatly, however a breakdown in form can cause added stress on your lower back so care needs to be taken.
The basic idea of a forearm plank is to suspend your body off the floor by supporting yourself on your forearms and toes while maintain your body in a straight line or neutral position. Because your muscles are working but are neither shortening or lengthening it is called an isometric exercise. Isometric exercises are a fantastic way to activate muscles, it can take time to recruit muscles into a strong contraction, therefore this is a good way to “wake up” dormant or “lazy” muscles. Joints, especially in the lower back take the most stress when pressure is applied at their end of range, an example of this would be in full lumbar flexion bending forwards to touch your toes or arching your back. Added stress in these positions will greatly add to the risk of injury and speed up degeneration. Therefore an isometric strengthening exercise in the mid range or a more neutral spine will significantly decrease the risk of injury when compared to sit-ups or glute ham sit ups when the back is going into full lumbar extension and flexion.
To learn more about why injuries occur.
It is important to note that studies have shown that strength changes whether at a cellular (muscle) or neuromuscular level (brain muscle connectivity) strength changes during an isometric exercise will occur mostly in the position that you are being trained. While crossover to other ranges of movement for the muscle will occur the improvements in strength will mostly be limited to the position that you are working. This would be a major issue if you were strengthening a muscle such as a hamstring, where the majority of the tears occur at the end range or on a full stretch, either through a stretching or a contraction injury, which is trying to contract at a full stretch, this would typically occur when sprinting.
As you can see, strengthening the mid point of a muscle in this case would be a little pointless and in fact potentially even dangerous. However when training a core you are not just training a muscle, you are also training a position. You are training your body’s natural ability to hold a neutral pelvis, then to become strong in this neutral pelvis so that your spine and pelvic position doesn’t move into a poor position which will irritate your lower back and decrease your strength.
Another benefit of the plank exercise instead of traditional exercises is the decreased force placed on your lower back. Research has shown that a typical abdominal sit up can place compressive forces onto your lower back of 3300 Newtons (Axler & McGill 1997), where a forearm plank has been shown to produce forces of 1600 -1800 Newtons (Freeman et al).
Not only does the plank exercise improve your core strength but it has the added benefit of training your scapulothoracic muscles (shoulder blade muscles), your rotator cuff, your neck stabilisers as well as contributing to your overall conditioning. Below are many of the common planking technique faults explained.
Technique fault number 1 – Dropping your hips
Quite possibly the most frequent technique fault we see in people planking is sagging through the hips. This can occur as someone begins to fatigue, their abdominal muscles are unable to fight against the pull towards the floor and your pelvis begins to drop. When in this position your core will not be working and other muscles or joints will be taking up the slack. Some people will also start planking in this position, quite possibly because their core doesn’t have to work as hard in this position. The main issue with planking like this is it will often irritate your lower back. When your pelvis drops towards the floor you end up loading up the facet joints in your lower back. Much like when you arch backwards and you feel a little pressure in your lower back, this is similar to what is happening when you planking while sagging with your pelvis.
Technique fault number 2 – Anterior Pelvic Tilt
Similar to fault 1), having an anterior pelvic tilt while planking will place undue pressure on your lower back. Someone planking with an anterior pelvic tilt will have an arched lower back and their bum will be sticking higher into the air. While taking the stress off your abdominals and making the plank easier it will place more stress on your lower back and again cause more pain.
Technique fault number 3 -Lifting your hips too high
Having your hips high makes the plank easier to hold because it places less pressure onto your abdominals. What is the point of doing a core exercise that doesn’t really work your core?
Technique fault number 4 – Collapsing through your shoulders
When you plank you don’t want to feel like you are collapsing between your arms and have your shoulder blades touching behind your back. Instead you should be bracing your arms and shoulder blades. By bracing through your shoulders and arms you will strengthen you rotator cuff and scapular stabilisers, very important muscles to keep your shoulders injury free.
Technique fault number 5 – Pushing back with your toes and forwards with your arms
By pushing out in different directions you are creating a bracing force which means you don’t have to work your core as hard to hold yourself off the ground.
Technique fault number 6 – Letting your head drop
This is possibly done to help with some kind of full body crunch. Of course this puts undue stress on the neck. The last thing you would want to do during a plank is to cause a disc bulge in your neck.
Technique fault number 7 – Letting your neck go into hyperextension
Just like the rest of you body, when you plank you want to keep your neck in a neutral position so that your body is in a straight line from your head to your feet. Letting your neck go into hyperlordosis or hyperextension will place significant stress on the facet joints of your neck. Maintaining the proper plank position will not only improve your core strength but it will strengthen your neck as well.
Technique fault number 8 – Holding your breath
By holding your breath while planking you will be using your diaphragm to help stabilise your core. Make sure you keep breathing normally while you plank to help you recruit your core correctly.
What is the ideal plank position?
When doing a forearm plank you should rest on your elbows and toes with your pelvis off the ground. You will want to tuck your pelvis under a little to ensure you activate your abdominal muscles. Ideally you should activate your pelvic floor as well. The key is to hold this position until you feel your muscles start to fail, once your core muscles start to fail the pressure shifts to other areas and it’s time to stop.
When should you stop a plank?
Like most exercises you should stop when your form starts to break down. A breakdown in form causes compensatory behaviours where your body will do whatever it can to keep going, however by recruiting other muscles which are less suited to the exercise or shifting your weight to a stronger side will result in adaptations occurring. This can be from a muscular imbalance, where you will now have an uneven pull on your body, like having your wheels out of alignment on your car. The wear and tear is accelerated exponentially.
The other adaptations that may occur are changes to your movement patterns or technique. When you practice for a sport you train the correct movement pathways so that your technique becomes optimal, if you practice poor movements then your movement patterns will become suboptimal. An example would be if you are trying to train a more natural pelvis and you rotate into an anterior pelvic tilt because of fatigue, you are now reinforcing this position that you were trying to correct in the first place.
When you start to fatigue maintaining the plank position suddenly becomes a whole lot harder. You really have to concentrate on your technique, because this is where faults in your technique become more prevalent as you try to find ways to keep on planking. So when your core muscles start burning and your body starts to shake, really concentrate on your technique to ensure you don’t start loading areas like your lower back incorrectly.
If your lower back starts to hurt when planking, most likely it is compensating for a weak core. When this happens the zygapophyseal joints or facet joints will be taking most of the load instead of your abdominals. This is a really good indicator that you need to stop, reset and then try again. You will make much faster progress when you plank correctly instead of pushing through needless pain.
One great attribute of planks is it’s ease of adjustability. Plank variations can make the plank substantially easier or harder. The harder part is knowing when the exercise should be progressed. The exercise has to be done at a high enough intensity for adaptations to occur in the muscles but yet maintain the correct technique so that negative adaptations do not occur. A safe place to start is if you are unable to hold a plank for at least 20 seconds then you really need to consider if this plank variety is too hard for you. Plank can be made easier by balancing on your knees instead of your toes. Conversely if you can hold the plank longer than 1 or 2 minutes then you can consider making the plank harder. One way to do this is to do the plank on an unstable surface such as a Bosu or exercise ball, lifting one arm or leg or even adding some weight to your plank. Other varieties include a side plank, a side plank will build strength in your obliques and glutes.
It’s important to realise that a plank forms a base for many other exercises you perform in the gym such as a push up. When doing a push up correctly your trunk will stay aligned and strong so that no force is lost when you push with your arms. There is also a cross over into everyday activities, think pushing a heavy shopping trolley, if you don’t engage your core correctly you may in fact take the pressure in your lower back which could lead to low back pains.
Freeman S, Karpowicz A, Gray J, McGill SM. 20006. Quantifying muscle patterns and spine load during various forms of the push-up. Medicine Science in Sports and Exercise. 38:570-77 https://pubmed.ncbi.nlm.nih.gov/16540847/
Axler C, McGill SM. 1997. Low back loads over a variety of abdominal exercises: searching for the safest abdominal challenge. Medicine Science Sports and Exercise. 29:804-11