Core Stability – the basics – monthly talk 9/7/18

Superman – done correctly

The structure of the skeleton and the generation of movement by muscles is a mechanical issue. So let’s start by looking at the relevant anatomy.

ANATOMY

  • Structure of the spine – 7 cervical, 12 thoracic, 5 lumbar vertebrae and the sacrum (4 fused)
  • Natural curves of the spine – kyphosis/lordosis
  • Weight bearing properties (slumped v. neutral spine)
  • Inter-vertebral discs IVD– shock absorbing/ gel like centre – nucleus pulposus/ annulus rings / repeated flexion and extension causing injury. Anyone from mid 30s onwards will have signs of IVD disease (IVDD) – it’s an ageing change. (See gel pack).
  • Movement in 3 planes –sagittal, divides the body in to left and right (actions: flexion/extension)/ frontal, divides the body in to front and back (actions: lateral flexion/extension)/ transverse (action: rotation)
  • Huge increase in compressive forces on IVD with flexion, lateral flexion and rotation – always move your feet to lift an object instead of twisting down to lift it
  • Posture for maximal performance/reduced injury in sport (and life) is a “neutral” spine
  • In order to maintain a “neutral” spine, we need a strong core
  • Hare bones – see how they fit together, where the IVD lies, how the facet joints interlock, where the spinal cord runs through the centre, where the spinal nerves emerge from the inter vertebral foraminae between the bones and how little range of movement the bones have in any of the 3 planes.

CORE

  • The body between the thorax and the floor of the pelvis, with the spine running through it
  • Boundaries are the diaphragm at the top, the abdominal muscles around the middle and the pelvic floor muscles and sides of the pelvis at the bottom
  • Stabilisation of the spine is by posture first and muscles second. Good posture allows the forces through the spine to be optimally withstood with minimal muscle involvement. When there are forces on the spine which act to move it from neutral, (eg movement of the limbs) then the muscles “fire up” to keep the spine in neutral and protect the back from injury. So what are the muscles which stabilise the core and where are they?

CORE MUSCLES

  • Diaphragm. Moves down in inspiration/up on expiration.
  • Pelvic floor muscles
  • Erector spinae muscles (longissimus/iliocostalis/splenius)– the long muscles running parallel to the spine
  • Deep spinal muscles (interspinalis/semispinalis/spinalis/rotators/multifidus)– closer to the vertebrae and deep, some spanning only 2-4 vertebrae
  • Muscles of the spine play a very important role in stabilising the lumbar vertebrae
  • Abdominal muscles (transversus abdominis or TA/ internal and external abdominal obliques/ rectus abdominis – the “six pack” muscle)
  • TA is like a corset around your middle. It increases intra-abdominal pressure on contraction, which stiffens and stabilises the lumbar spine
  • Trunk muscles (latissimus dorsi/quadratus lumborum/gluteals)

Together these muscles stabilise the core and help maintain a “neutral” spine during movement. This has 2 important consequences:

  1. Prevention of injury. The lumbar spine is mechanically weak. Excessive forces during movement can cause damage. ( IVD, annular rings and delamination under repeated compression /disc herniation/facet joints/muscles especially QL, nerve entrapment)
  2. Improved performance. The core must be stiff to transmit the forces generated by the limbs (tennis players hitting the ball, runners or cyclists transmitting forces through the ground or pedals, sports involving jumping). A weak core dissipates the forces generated and the effect of any movement is reduced, so you run/cycle slower, jump less high or far, hit with less power. Weight lifters generate “super stiffness” by recruiting more motor units within their muscles to enable them to lift heavy weights.

What is different about training core muscles to other muscles?

In the past, training the core muscles has focussed excessively on TA (to increase intra-abdominal pressure and make the spine more rigid) together with repeated flexion/extension from sit-ups/back extensions which create damaging forces on the IVDs. This is applying the same training techniques to the small stabilising muscles of the spine and abdomen as to “prime mover” muscles such as quads and biceps, which move the limbs. Prime mover muscles move through a large range of motion and are “fast twitch” muscles generating a large force over a short time. But core muscles are “slow twitch” endurance muscles which contract steadily for long periods of time and move through a small range of motion or not at all. So unlike training limb muscles, core stability training should focus on very small movements or no movement at all, resisting the forces generated by instability whilst maintaining a neutral spine. The development of core stability enables an athlete to “flow” – to move effortlessly as the core muscles maintain good posture for long periods of time while the big “prime movers” do all the work.

How not to do a “superman” – excessive IVD pressure generated by overextension of the lumbar spine

 

Fishing rod +/- guy wires

Motor control errors – many back injuries caused by failure of deep, small muscles to “fire” quickly enough as the spine moves eg picking up a pencil from the floor, bending over the sink. Training core muscles involves training the neuromuscular system to activate these small muscles quickly. Balance training is important for this.

Moment arm – the further away from the lumbar spine the object is, the greater the moment arm (15x at arm’s length) and the harder it is for the spinal muscles to stabilise the vertebrae

Eg hoovering/ opening a door/ pushing or pulling an object/holding an object at arm’s length

5 stages of core stability training

  1. Posture – sit/stand/walk with a neutral spine (slump/sit up, shoulders back and down, rotate pelvis to stand tall, walk with arms swinging from shoulders)
  2. Endurance – learn to maintain that posture without the muscles getting tired (see 3 basic core exercises later)
  3. Movement patterns – learn to move from one posture to another whilst maintaining a neutral spine. (squat and lift/lunge/twist/push/pull/balance). Train movement not muscle. Learn to hip hinge (squats/stand from sit/rowing/good mornings/Arabesque).
  4. Strength – increase the ability to keep a stable spine as load increases (more challenging core exercises in the next talk!)
  5. Power – (force x velocity) comes from the hips not the spine. High spinal velocity/low torque OR low spinal velocity/high torque but NEVER high spinal velocity/high torque. The faster your spine moves under load the greater the risk of injury (explosive jumping/throwing).

A note on stretching.

Back flexibility is NOT required for good performance. Flexibility without strength and motor control is useless. In fact the soft tissues of the spine have a passive stiffness and loss of this stiffness by stretching may lead to injury. So:

Don’t stretch your back beyond the range of movement required for competition.

Don’t stretch at all for the first couple of hours in the morning – the IVDs are more turgid with fluid after lying down overnight and are more susceptible to injury.

Don’t do “silly stretches” in which your lower back flexes (usually aimed at the hamstrings).

Lumbar flexion rather than a hamstring stretch

3 BASIC CORE EXERCISES – Superman/side plank/curl ups

 These 3 exercises are described as “The Big Three” by Stuart McGill who is an expert on back pain and rehabilitation of top class athletes with back injuries (see the bibliography).

He advocates these 3 simple exercises which work the core in all 3 planes and develop posture and endurance – the first 2 aspects of core training.

Warm up with the “cat/camel” to decrease the viscosity of the IVDs and reduce the stress on them. This is a motion exercise and not a stretch. Don’t push beyond a comfortable range of motion, move slowly and constantly and repeat it 5-6 times.

Superman  2 x 10

Face down on your hands and knees, back neutral. Slowly lift one arm and the opposite leg (keep them straight) to horizontal and hold it there for a few seconds then return under control. Do not allow your back to leave neutral. Repeat with the other arm and leg. This exercise is all about control – perform it slowly and do not allow your hips to shift side to side.

Side plank 2 x 1 minute (building to 2 minutes) each side.

Side plank support on elbow and feet. Have heel of top foot just in front and contacting the toes of the other foot (not feet on top as in this photo but as below in a slightly more advanced version).

Raise hips off floor and hold. Keep hips forward and squeeze glutes. Do not allow top shoulder to drop forwards. Start with 7-8 second holds at first then increase the number of repetitions i.e. start with repetition rather than duration

Curl ups 2 x 10

Lying on your back with your arms folded across your chest. One knee bent at 90’.Engage your core and slowly lift your shoulders 30 degrees off the floor using your abdominal muscles. DO NOT flex your neck. Lower under control back to the floor.

(Personally I find clients struggle with good technique doing curl ups and find it hard not to engage their neck so an alternative to curl ups would be:

Bent leg lowers 2 x 10. Flat on your back with knees and hips bent to 90 degrees. Maintain your back against your hands (between your lower back and the mat) as you lower both legs to the mat and back to the start position. Do not allow back to lift off your hands. Breathe out as leg goes down and in as it comes back to avoid breath holding.)

Bent leg lowers

These 3 exercises work the core muscles in all 3 planes whilst keeping the back in a safe, neutral position. If you attempt them and are unable to maintain good technique as you tire – STOP.

The second talk on core stability will look at Stages 3, 4 and 5 of core stability training (movement patterns, strength and power) and demonstrate a range of more challenging exercises.

Bibliography

  1. Pocket Atlas of the Moving Body (2000) by Mel Cash
  2. Low Back Disorders (2007) by Stuart McGill PhD
  3. Ultimate Back Fitness and Performance (2009) by Stuart McGill PhD
  4. Strength and Conditioning for Triathlon (2013) by Mark Jarvis
  5. Essentials of Strength Training and Conditioning by Baechle and Earle