Practioners and athletes often equate trunk control with “core stability” and the ability to activate and utilise the deep abdominal group (rotatores & intertransversarii). In fact numerous hours of core stability work have been introduced to world class athletes via classes with physiotherapists or one to one sessions via their conditioning coach. The main aim of these classes has been education and recruitment of these muscles at 30 – 40% of their maximal voluntary contraction capacity (mvc).The monitoring of these athletes and their ability to recruit the core muscles has been able to demonstrate the success of some of this work in lowering pressure and shearing forces on the back. Indeed, there are also many anecdotal cases, one in a premiership football club that educating the players to “click on” and work the core has decreased the reported incidence of lower back pain.
Nevertheless, whilst “core stability” may have a role to play in sporting performance and injury prevention of the lumbar spine, the concept of “trunk control” for spinal stability in vigorous, dynamic movement synonymous with sport and fitness is a major area to train. This area is often now sacrificed for deep core work only, or is deemed taken care of by traditional abdominal fitness sessions. The problem with focusing primarily on the transverses abdominus and multifidus is that some literature suggests that their primary role is for proprioception (providing positional feedback of the spine) and are very limited in their ability to act as dynamic stabilisers, due to their inability to cope with high forces and high fatigue rate.
The suggestion is not that some of this core work should be replaced by traditional abdominal workouts. These exercises typically involve lots of repetitions of the abdominals working in a flexed position. Professor McGill’s needs analysis work of most sporting movements suggests that the role of the trunk is to support the spine in an extended rather than flexed position. This is demonstrated below in an example with 400m sprinter Iwan Thomas.
A sprinter has to maintain this extended position and stabilise the spine despite high breathing rates, high ground reaction forces being transmitted and dissipated through the body, and high power outputs being produced within the body. A major task! Would either core stability work operating at low intensities or abdominal strength developed in a flexed position to cater for these high demands?
It is for these reasons that Olympic lifting and overhead derivatives are fantastic not only for their performance objectives of developing strength and power, but for training the trunk in an extended position, despite high force and neuromuscular demand. The lifter has to synchronise the firing of the stability groups to produce the high forces necessary to cope with the load above. Synchronisation of the stabilisers is also a major contributing factor to injury prevention of the lumbar spine.
An individual’s ability to assess “trunk control” can be performed by simply timing how long they can hold excellent form in the plank and side plank positions.
In the plank the athlete must be instructed not to raise or lower their hips and aim to maintain the body in a straight line. Some athletes with poor scapula control will want to round the shoulders, or overly retract the scapula causing a cavity between the shoulders, so make sure they are also focusing on correct scapula control. Incorrect postural control will have an impact on maintaining the desirable extended trunk position. Similarly, watch for lowering on raising the hips in the side plank position, putting the elbow too wide (not under the shoulder) to create a wider base or demonstrating poor control of the scapula allowing protraction.
For more detailed information on this area a great book to read is Professor McGill’s (2002) “Low Back Disorders”. McGill suggests that at an elite level these positions should be maintained for two minutes! McGill also describes the structure of the trunk to be similar to a tent, with the spine functioning as the tent pole and the guide ropes the muscles acting as the stabilisers. All the guide ropes should provide equal support and should operate at the same time. Equally if one side is weaker than the other their maybe unequal forces or synchronisation patterns suporting the spine causing performance dysfunction and potential injury.
Olympic weightlifters demonstrate tremendous strength in the trunk in an extended position in lifts such as clean and jerk and the snatch. Huge forces are generated to lift loads form the floor to an overhead position. This is also a fantastic lift for many athletes/sports people to utilise as it is multi faceted in its training aims. You can efficiently train whole body strength, power, balance and neuromuscular recruitment in one exercise. Therefore minimising time demands on a conditioning session with an elite athlete who will have technical areas to train in conjunction with vast amounts of time spent with other members of the sports science support team.
Below are examples of exercises that are excellent for placing high demands on trunk control.
Split jerk, power jerk or derivatives such as jerk recoveries.
Power Snatch or derivatives such as overhead squat, snatch squat and snatch balance.
These exercises have a high technical component and should be taught by a conditioner trained in Olympic lifting principles. However, in my experience athletes have a great capacity to learn new techniques and are usually co-ordinated enough to take these principles on board in a short period of time. This is sometimes hindered by their high volume high intensity training load outside of the gym, particularly in the general conditioning blocks of their periodisation. However, some of the power based athletes use red bull to prep them an hour or so before the gym, and they are able to focus and train through the high power demand of the Olympic lifts.
Of course these exercises can be complimented by other trunk work, particularly those that are utilised in extension such as bar bell rollouts. Your imagination is your only limiting factor!