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What is the Core?

I am Robert Beighton, Everyone Active’s national fitness expert. I am back with another three part fitness series to hopefully help you gain a better understand of the core! See the first episode below.

The different muscles of the core.

Although there is ambiguity about what constitutes ‘the core’, and physical evaluation of its function is variable (Kibler, et al., 2006) (Clark, et al., 2018), for the purposes of this video, we define the core as ‘the trunk or lumbopelvic region of the body (Wright and Steele, 2013).

  • Your abdominal muscles (transverse abdominus, rectus abdominus [the six pack], internal and external obliques)
  • Posterior muscles (muscles on your back)
  • Diaphragm (top) and pelvic floor muscles (bottom)
  • PLUS, any other muscles they connect to via fascia (the web that connects all our muscles) – at the very least we are now adding all the muscles of the shoulder, upper back and hips to our definition of core.
  • The definition can be to the extreme – all muscles in the body are connected so the core does not have a beginning and an end, it is everything.

So then, what does “core strength or stability exercise” even mean?

Difference between core strength and core stability

We can define ‘core stability’ as ‘the anatomy that holds the centre of the body solid to create a stable foundation ‘from which the limbs can freely move’ (Norris, 2009), to optimise the transfer of loads along the kinetic chain (Huxel and Anderson, 2013). ‘core strength can be defined as the ability of the musculature to produce force through con- tactile forces and intra-abdominal pressure (Hibbs et al., 2008). However, core strength should not be misconstrued with core stability, although it could be argued that the distinction between core strength and core stability is distinctive yet inseparable. Studies have shown that an increase in core strength has a causative effect on core stability (Hsu et al., 2018).

Core myths, including the contentious issue of core stability

I often get clients ask me how to strengthen their cores, they are confused as the amount of misinformation is enormous and despite the myth of core stability being debunked as early as 2007, (Lederman, 2010) the number of fitness classes promoting “hard abs” or a “strong core” to “protect the lower back” does not seem to be disappearing. I also used to plank a lot and do loads of core exercise, so I do not blame people, but I want to help. Here are the common myths:

  • That certain muscles are more important for stabilisation of the spine, in particular transverse abdominis (TrA). The division of the trunk into core and global muscle system is a reductionist fantasy, which serves only to promote CS (Lederman, 2010).
  • That weak abdominal muscles lead to back pain and strengthening them can reduce pain. A couple of decades ago it was found that people with chronic lower back pain had delayed transverse abdominis muscle activation. The researchers did not make the leap to say that strengthening transverse abdominis would prevent or treat lower back pain, but it seemed that those in the fitness industry did. Chronic lower back pain is common and there is little evidence to support it being linked with a lack of core strength, with the evidence we do have being correaltionary not causal. What we are learning from science is that long-term pain is more about the nervous system and is multi-factorial and very different for each individual.
  • That there is a unique group of “core” muscles working independently of other trunk muscles. In normal human movement, muscles do not work in isolation. They co-contract. Even when you are doing an exercise to target a specific muscle or muscle group, it may target that group more than another muscle group, but no muscle works in isolation.
  • Planks are the best! Wrong. Compound movements are much more effective, although the plank or various exercises from hands and knees position may increase and develop awareness skills, the level of activation measured is too low to see actual strength gains.
  • Engaging the core. We know from studies, that the amount of trunk muscle activation required to stabilise the spine for normal standing, walking and breathing is so low that it falls beyond conscious control. All these muscles naturally respond to load demands, when you lift heavy materials, they naturally increase their level of engagement. As for hugging navel to spine, what does this even mean? You could ask several trainers and get a different answer from all of them, if they do not know, how should a person with little scientific knowledge of the physiology of the body. This cue is confusing. For breathing and natural, reflexive core function I want soft abs not hard ones.

Why is core strength and stability important for everyone?

There are several potential benefits of core stability training (Lawrence, 2003) and these benefits can be applied to everyone. It has been suggested that core stability training can improve pelvic and spinal stabilisation, thus an improvement in posture (Hoppes et al., 2016). An improvement in spinal and pelvic stabilisation can also prevent injury, (Graves et al., 1994), as compromised core stability creates an ‘unstable proximal base’, which can limit control of functional movements like lifting heavy weights (Hewett et al., 2009).

Balance is an important element of any sport and fitness, as it enhances motor skills (Hrysomallis, 2011), an essential element for safe and effective lifting of weights and everyday activities. One study found that after a six-week core stabilisation training programme, balance improved and had a positive effect on athletic performance (Sandrey and Mitzel, 2013).

Another useful effect of core stabilisation training is its ability to increase lactate threshold (Navalta and Hrncir Jr, 2007). A positive effect for those who like to train, as the ability to work the muscles harder, as a result of this higher lactate threshold, could increase hypertrophy.