Stability training myths: considerations for the power athlete

When we load our bodies through various lifting exercises, we want to limit any spinal movement that occurs. Force production in the upper and lower limbs is increased when the athlete maintains a stabile core, and a stabile core also minimises any spinal movement. On the other hand, force production will become hindered with inefficient stability that may occur from improper lifting technique or an injury. Power athletes need certain capabilities to be successful, and one of those is stability, i.e., static and dynamic stability. The ability to stabilise is generated from the athlete’s core, with muscles of the trunk, back, glutes and shoulders all working in sync to prevent unwanted movement of the spine as well as maintain balance. This is known as inter-muscular coordination and will produce greater amounts of force as opposed to individual muscles working in isolation.

Some literature has suggested, for athletes to be capable of moving explosively with control and precision, they must brace the trunk through inter abdominal pressure. Inter abdominal pressure is generated through inter-muscular coordination of the transverse abdominis and the internal and external oblique muscles, thus, applying pressure through co-contraction of the muscles, helping to create a safety mechanism to protect and stabilise the spine (1,2). The trunk muscles do help with creating and transferring energy to maintain posture, but there is insufficient evidence that solely exercising the trunk will assist with the explosive movement’s athletes need to perform.

An athlete who requires power will need to express large forces in a very short time, so the ability to successfully stabilise the core through inter-muscular coordination is essential. An example of this would be the Olympic weightlifter, who has to move a loaded barbell that is up to twice their bodyweight as quickly as 1 or 2 seconds; or a boxer who has to be capable of generating enough potential energy from the core to transfer it to the limbs as kinetic energy into a punch to knock out an opponent. In coaching practises or rehabilitation clinics, unstable surfaces such as balancing on wobble boards or bench pressing on swiss balls have been used with the intention that athletes will adapt to this environment and improve stability due to the greater effort required to maintain balance. In theory this may seem justified, however there are several issues with this concept. First, the power athlete performs their sport on the ground and not on an unstable surface. Additionally, using unstable surfaces will reduce movement velocities, and since sports are performed at high velocities, this will only result in a contradiction of training specificity and limit transfer to performance (3). Second, the lack of intensity that is required from this type of training is reported to be up to 40% lower than the desired threshold to create training adaptations for athletic performance (4). Taking this into consideration, increasing movement velocity or the intensity to a heavy enough training load to create the desired training stimulus will make the training exercise more difficult to perform, putting the individuals at risk of injury. Furthermore, athletes are required to move explosively with control and precision, therefore they’re required to have dynamic balance, and unstable surfaces will only improve the athlete’s ability to maintain balance while on an unstable surface.

“using unstable surfaces will reduce movement velocities”

The kettle bell half kneeling bottoms up press (Image 1) is a great exercise to improve inter-muscular coordination in athletes. Due to the athlete having to maintain the position of the kettle bell, this creates tension in the arms and into the shoulders, requiring additional activation from the stabilising muscles. Once athletes can perform the kettle bell bottoms up press successfully, the bandbell bamboo barbell standing press can then be prescribed. The bandbell bamboo standing press will challenge the lifters stabilising muscles due to increased movement variability. The athlete is required to limit movement variability but will become challenged as the kettle bells oscillate, which are hanging from the end of the bar on resistance bands (Image 2). The athlete will become highly challenged to follow a strict bar path due to the oscillating kinetic energy. This exercise will improve inter-muscular coordination as well as intra-muscular coordination, which is the coordination of single muscle fibres within a muscle. When the fibres within a muscle contract and relax in sync, the muscle will be capable of producing greater force.

Image 1: Half kneeling bottoms up kettle bell press. Image taken from https://www.youtube.com/watch?v=TtBEt3km83s
Image 2: the original bamboo barbel. Image taken from https://powerliftingtechnique.com/bandbell-bamboo-barbell/

As athletes progress, ground based exercises using loaded barbells can be used next to increase inter-muscular coordination and improve stability. This will increase functionality of training, and since athletes need to be functional, this manner of training will be best because most sports require the athlete to be in an upright standing position, thus, increasing specificity. While using a bench press to improve the tackling strength may seem justified, the strength and stability to perform a strong tackle is similar to the example of the boxer above, i.e., potential energy created from the core and transferred to the limbs as kinetic energy will improve tackling strength via stability (5–7). Multi-joint, ground based exercises are the ideal choice for athletes to train with, using both bilateral and unilateral stances this can mimic the sports event that the athlete is training for (7). For example, back squats, deadlifts, power cleans, split squats, lunges and overhead presses. All these exercises require the ability to apply force from the core to the extremities. While using multi-joint barbell or dumbbell exercises, the athlete can create the desired training response using the appropriate intensity to help them improve strength, power and stability.

References

1.         Behm DG, Drinkwater EJ, Willardson JM, Cowley PM. The use of instability to train the core musculature. Appl Physiol Nutr Metab. 2010 Feb;35(1):91–108.

2.         Borghuis J, Hof AL, Lemmink KA. The importance of sensory-motor control in providing core stability. Sports Med. 2008;38(11):893–916.

3.         Behm DG, Sale DG. Velocity Specificity of Resistance Training. Sports Med. 1993 Jun 1;15(6):374–88.

4.         Wirth K, Hartmann H, Mickel C, Szilvas E, Keiner M, Sander A. Core Stability in Athletes: A Critical Analysis of Current Guidelines. Sports Med. 2017 Mar;47(3):401–14.

5.         Norwood JT, Anderson GS, Gaetz MB, Twist PW. Electromyographic activity of the trunk stabilizers during stable and unstable bench press. J Strength. 2007 May;21(2):343–7.

6.         Speranza MJA, Gabbett TJ, Johnston RD, Sheppard JM. Effect of Strength and Power Training on Tackling Ability in Semiprofessional Rugby League Players. J Strength. 2016 Feb;30(2):336–43.

7.         Tvrdy DP. A Novel Technique: Strength Training for American Football Tackling.  [Miscellaneous Article]. ET J. 2011 Feb;33(1):76–80.

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