Ultramarathons. What , why and how are the questions I'm most commonly asked. Hopefully you find some answers here from my own personal perspective. My other blog at www.mile27.com.au/blog is full of information on running and health and fitness in general.

Tuesday, 8 December 2009

Plank or Crunches , which is the best core exercise for runners?

It’s been a while since my last blog but I’ve got a very topical one for you today. It’s long but take your time and read through it because if you want to learn how to strengthen your core specifically for running you’ll find the answers. Some of you may disagree with me as I challenge some conventional beliefs but this is all derived from applied functional science and is the work of far greater minds than mine.

There has been a lot of importance placed on strengthening the core over the last 5-10 years and a strong core is now seen as a prerequisite for optimal performance. Despite the increased awareness there is lack of real knowledge as to what the core is, what it does and most importantly how to train it.

What is the core?

We often think of the core as simply our abdominal muscles but there is a lot more involved. All the muscles that attach to the pelvis, the abdominals , the spinal muscles, pelvic floor muscles , deep hip muscles, scapula and shoulder girdle muscles make up what we refer to as the core. These muscles are not one big group of muscles that all activate as “the core”. They act depending on the load placed on them.

What does the core do?

The core is responsible for providing the legs and arms a strong platform from which to work. Think of your arms or legs as the arm of a crane and your core as the cranes base. If the base is unstable then the lifting capacity of the crane will be affected.

How do we train it?

There are literally hundreds of different exercises that are claimed to strengthen the core. The problem is that some of them don’t train the core at all and many of them only train the core to be stronger in one particular position. This may or may not be helpful depending on what you need a strong core for.
In our case we are looking at increasing our core strength for when we run. The type of strength required in the core by an Olympic weight lifter, a rugby player, a rower and a runner is going to differ greatly. So it makes sense that certain exercises would suit one sport but not others. Surely if the demands on the core are so different then there should be different core exercises for each particular sport? Why then are core exercises like the plank universally prescribed no matter what the sport?

This would be like saying if you want to improve your running you should do 800m intervals. This might be great for middle distance runners but is of little relevance for rugby players or tennis players. Specific training for specific sports is a concept that all coaches follow but seem to ignore when it comes to core training.

How do we switch our core on and why has ours switched off.

Muscles are “switched on” when the resting tension in a muscle increases. Effective muscle function involves a loading action just as you would load a rubber band by stretching it before releasing it. The more force put through the muscle in the loading phase the more force the muscles can produce. Think of what happens when you want to jump. Your first action is to squat down to load the muscles before you spring back up. The higher you wanted to jump the lower you would go and the faster your movement would be.

Core muscles work the same way. If they are put under load they will switch on. If there is no change in tension then there is no reason for them to activate. No movement equals no demand on the core, so sitting at a desk all day is a great way to switch off our core muscles!

How do we put the core muscle under load?

To put a muscle under load we need to place it under tension. The best way to do that is to take it through a dynamic stretch. For example if you are playing tennis and you want to play a forehand shot, your first action is to rotate your body backwards, this places the oblique abdominal muscles under tension so they can spring back and rotate your body forwards providing the power for your forehand shot.

How does this relate to running?

In running the core muscles are switched on by the loads placed on it by the legs and arms. As your right foot lands your left leg is behind you and your right arm behind you. This places a diagonal load or tension from your left leg to your right arm through your core which “activates” the core muscles.

The gains from any particular exercises are specific to the load, speed, joint position and energy system.

What this means is if we train our legs for example on a leg press machine then the strength we gain will be help us whenever we are lying on our backs pushing a weight away from us with our legs. Whilst this may be of use for a rower it isn’t of any use at all to a runner. The best exercises for a runner will involve standing or landing on 1 leg with the other leg behind us.

Because of this if we want a core exercise that will help us to run better then we need to look at exercises that use the arms and legs to place a load on the core that is similar to the load we experience when we run.

So enough of this theory which exercise is best – crunches or plank?

Hopefully you can now start to realise that neither exercise is very good at all. Crunches involve you lying on your back and lifting your upper body up against gravity. The plank involves supporting your body weight against gravity whilst resting on your arms and legs.

When we run the biggest movement of our torso is rotation which is driven by our arms and legs. Why then, do all the core exercises we do involve very little or no rotation? If thats what our torso does when we run surely we need to train our core to be better at that movement as that is what happens when we run.

So neither are very good – surely they cant hurt?

Unfortunately not only are these exercises not relevant for runners they will actually make the core WEAKER! Performing lots of crunches will tighten the front abdominal muscles creating a more hunched over posture which will reduce the amount of movement in your middle back which will reduce the load on your rotational and lateral core muscles making them weaker.

The plank is an exercise in which people need to use their rectus abdominus (six pack) muscles to stop their back from arching. This overloads the muscle to the detriment of the more internal muscles of the core. You end up with a strong six pack but completely dysfunctional core. Great if you want to lie on a beach and do nothing but not much good for running.

But I really feel my core work when I do these exercises

Unfortunately you are feeling your rectus abdominus work which makes up a very small part of the core. The problem is that this muscle is often recruited by the body at the expense of the other core muscles. So it gets stronger and the other muscles due to lack of work become weaker.

So what exercises are good for the core?

Exercises that involve standing up, preferably with one foot in front of the other and then using the arms or legs to place the core under load are the most beneficial for runners.

What does that mean?

For example standing in a lunge position and then holding a medicine ball and rotating arms from left to right, either at chest height or starting at knee height and rotating around to shoulder height or vice versa. See the end of this article for a video to show you how it's done.

Why should you believe me when everyone else is saying the plank is a great exercise?

Good question.

There is a universal law of training that every exercise professional will agree with.

The law of specific adaptation to imposed demand.

What this means is the strength gained from an exercise is specific to the load, joint position, speed of movement, energy system and range of the movement of that exercise.

When you think about that it makes intuitive sense. We all understand that even though bike riding and running both use our legs if we want to run faster then bike riding is a poor choice compared with running. Ok, there is some benefit as your heart and lungs have to work in both but obviously running would be a better way to use your time. The action of the legs is different in riding a bike compared to running. Take Lance Armstrong – surely the fittest man to ever ride a bike. When he did the New York Marathon he just broke 3 hours, a time that many decent club runners can achieve.

Imagine if all the exercise professionals were saying that the best exercise to help runners in the gym is to ride a bike. You’d be thinking surely there must be something a bit more useful than that. Yet this is exactly what is happening with the core.

The strength gained in the abdominals by performing the plank is applicable when the body needs to support its weight against gravity with both hands and feet on the ground and needs to hold that contraction for a period of time. This makes it an ideal exercise to strengthen your abdominals for when you do push ups but it bears no relation at all to the strength you need in your abdominals when you run.

Let’s analyse what happens to our core when we run. Our feet land 90 times a minute and every time we land our spine and pelvis undergo a rotational stress (among others) which our core must control.

So an exercise that has one leg forward, one leg back and involves rotating our body rapidly would closely resemble what happens when we run. If we hold a medicine ball with our arms to add some resistance then that load will be greater than when we run. The body will adapt this and find it easier to control that rotation when we run in future.

There are some variations of a plank that involve lifting a leg and or arm of the ground and apply different stresses to the core and these are certainly an improvement. But thats like saying riding a bike standing up is better for helping runners. Yes it probably is but it’s still no where near as good as running.

I hear you still asking “Surely it can’t hurt, there must be some benefit?”

Well maybe, maybe not. If you are overloading the already strong muscles in your core and teaching them to hold a static position then it is certainly not going to help the weaker muscles of the core learn to contract and relax 90 times a minute when you run. The more the stronger muscles work the less the weaker muscles have to do so the weaker they become. Net result: weaker core for running.

If you want to do an exercise to help your running it must place a similar load on it that running does and in a similar position.

Give up the crunch and the plank and try these three running specific core exercises.

1. Lunge position with rotation

a. Holding a weight with both arms rotate your arms around horizontally
b. Rotating from a waist high position to a shoulder high position

2. Lunge position with sideways overhead reach

Holding a weight overhead with both arms reach to one side as far as possible and then the other side

3. Lunge position with overhead reach

Holding weight with both arms swing arms upwards over head.

See the video below for a demonstration of these exercises.

These exercises are designed for people with no injury problems so if you have any please seek advice before attempting these.

For those of you that read my blog on resistance training for runners you will recognise that these exercises sound very familiar. The only difference is that instead of lunging forward with the legs the legs remain fixed. This puts the emphasis less on the legs and more on the core.

There are many other exercises that work the core and for my clients I design specific ones based on their requirements and their specific strengths and weaknesses but these ones are great exercises to train the core in three different planes of motion.

But I don’t feel my core as much as when I do the plank!

You may not but what is the purpose of the exercise – to feel your abdominals work or strengthen them so they are stronger for running? Feeling something work is irrelevant particularly if its the wrong muscle! The muscles of the core only need to activate at around 10-15% of their maximum strength to provide adequate support to the body. The idea is they can continue to maintain this level of activation for a long period of time. Much like an endurance runner can run for a long period of time but not as fast as a sprinter. As runners we need to train our core to have enough endurance to support us throughout our races. For this reason your core exercises should be done at a lower intensity but longer duration.


Natalie said...

Brilliant read! I currently do the plank for 5 mins every morn...'rotating' 1 mins of front-side-front-side-front.. I am going to test out your theory and switch to the runner-specific exercises you suggest instead :) will let you know how it goes and if i notice any visible differences in strength/stability over a couple of months.

Need a med ball though, any recommendations of where I can buy one??


sharmanian said...

Interesting article, Andy. But one question - would a varied set of different core exercises not work the whole core and make it all strong? I've been doing classes recently which do about 20 different exercises, working on basically the whole area, but all in the horizontal position. I know that doesn't simulate running, but surely it strengthen the entire area required? Or would you say it's counter-productive? It's a hard workout.

Andy said...

Hi Ian

The problem with primarily horizontal position exercises is they only work the core in one plane. All our joints move in three planes - forward backward (sagittal plane) sideways (frontal plane) and rotational (transverse plane). When we run the core has to deal with loads occuring in all three planes. If we only train one then we may be very strong at controlling that plane but weak when it comes to the other two planes.

Whether its counterproductive or not depends on the relative strength of your core muscles. Some people when they try and load their core recruit primarily their rectus abdominus (six pack muscle) at the expense of many of the other deeper stabilising core muscles. This means 20 minutes of horizontal core exercises would definitely be counter productive. Other people may have a good recruitment of the deeper core muscles in which case the only problem with the workout is it doesnt address the other two planes of movement.

The fact you are able to race often and at a high level seems to indicate that you core must be doing a pretty good job. Not saying it couldn't be improved though with a few exercises in the transverse and frontal plane ;-)

Anonymous said...

Andy, fascinating as always...I thought the answer would have been the Plank.....thx

Mike M