Mobility, stability, strength; the great debate

Better late than never.. That seems to be a theme for me of late. Sometimes life just gets busy though.

Thanks to the talented Robbie McCullagh, strength and conditioning coach with the NSW Police Force, for delivering his reflective and insightful thoughts on this ever growing topic. I asked for definitions of the terms; mobility, stability, strength and flexibility and then an application of these components within high performance scenarios AND rehabilitation scenarios. To stimulate more of a debate, if you feel so inclined, share your knowledge and provide me with your thoughts!

Robbie’s responses:

Mobility: The freedom of movement. From an S&C perspective this is mostly seen by an athlete who can or can’t get into the posture you are asking for (e.g. a lunge pattern) or to achieves the range by taking it away from another area (. e.g Overhead deep squat, you will commonly see and athlete achieve full depth but the arms and head are in correct alignment). Probably the most confusing for a S&C coach as the reason for that mobility restriction could be several things.
Stability: The skill to have static contractions of a group of muscles to control a joint. When most S&C first hear of “stability” they think about a joint that is locked and doesn’t move. Although a locked ankle that may not over pronate is beneficial (i.e rigid strapping tape), stability for me must be more than that and be a motor control skill of the athlete that can be turned on and off when required.
Strength: The ability to produce and absorb force with another object. Simple but very important.
Flexibility: The ability of soft tissue and joints to move through a range of motion. It is not just the sarcomeres but also the tendon and joint health itself.

How do you see the interaction of these leading to increase performance?
All 4 are constantly coming in and out of play when addressing performance objectives with an athlete and the level to which each play is dependent on the task at hand.
The easiest scapegoat for an S&C when something is lacking is the strength component. Strength is so important in athletic movement patterns that enough is never really enough. A strong athlete you can make fast, powerful, reactive, durable and efficient in all movement patterns (i.e a high performer). The only reason we don’t constantly chase strength is the effort to reward ratio becomes too large and we lose focus of the other athletic attributes.

Although strength is the easy scapegoat it’s not always the best when increasing performance levels. You can throw plates on the bar every week but if you don’t have the flexibility, mobility and stability you aren’t going to improve. Sometimes the best way to increase performance can be addressing the weakest link or as a good physio once told me, take the handbrake off. For example, if the athlete can’t get into postures to generate or absorb force in a task then it doesn’t matter how big their squat, deadlift or bench is; their force transfer doesn’t exist so their performance outcome will suffer due to a mobility issue. Another strategy for addressing the weakest link is increasing stability of a joint so muscles have a stable base to work from. Common joints this applies to are the shoulder and hip. So many athletic movements require the arms and legs and as mentioned, if the base is unstable (e.g. shoulder girdle or pelvis) it’s hard to be efficient in transferring 100% of the force generated to another object.

How do you see the interaction of these leading to rehabilitation?
Not much changes when coaching rehabilitation because all 4 components are still required before you can confidently discharge someone from the rehab group. Over the years I tend to look for mobility, stability, strength and flexibility concerns in slightly a different light of importance in the rehab population. As with performance outcomes, all are still important and addressed but in most cases mobility needs to be frequently re-assessed as the first limiting factor. Weather the mechanism of injury is acute and the limb has been mobilised or it is an overuse injury in both cases mobility exercises will be programmed regularly throughout the rehabilitation.

While mobility is usually the first adaptation we are looking for, stability and strength are just as important.  Strength still needs to be the driving force and big picture goal of the program. Too often I think as practitioners we address the swelling, the pain and range of motion of the limb but neglect the strength component before discharge occurs. We often return them to day to day strength capacity (i.e it feels easy to move around) but what if often needed is strength capacity to compete in their sport or if possible with a capacity that is above those that the athlete is exposed to in their sport. When load is greater than the athlete’s capacity even on discharge, I would be recommending the strength training should still be included and prioritised in their fitness training. Even in the absence of pain, when training or competition loads are greater than the athlete’s capacity the chances of re-injury are still high. It’s hard to prioritise when your players need to train and compete but a simple solution to this is coach the athletes through progressions and regressions of the movement patterns required. Manipulate the environment with changes in base of support and mechanical load into the limbs and match it to that of the sport/ requirements as supplementary work during their normal training sessions (e.g. warm ups, movement preps etc).


Connor’s responses

 Mobility is best described as the athlete’s ability to reach the intended range in a specific skill; it is a weight bearing and multi-joint concept (Ref). Mobility, therefore, is highly dependent on stability and coordination of multiple joints. It can subsequently confusingly be associated with coordinated movement and is espoused to precede a highly-developed locomotor apparatus; a strategy of preventing accidents from happening (Ref). This confusing ‘catch-all’ term has led to a wide discrepancy in what is currently termed mobility training. A solution may be to use the term ‘early motor control’ in some drills instead of ‘mobility’ to avoid confusion.  To my knowledge there have been no long-term trials or review studies on the effectiveness on mobility training on performance in comparison to programs without mobility training included.
Stability: Although the concept of stability is very easy to grasp – ‘the state of being stable’ – a definition for this within athletic endeavours becomes more convoluted (Ref). The author contends there are four main important realms of stability within human performance; kinetic chain (upper and lower), girdle, lumbopelvic and trunkal. It is easiest to look at stability as the opposite of energy leakage through a skill performance. This definition is very dependent on Frans Bosch’s work, whether you love or hate him, I think looking at this concept in a more scientific manner is appropriate. A chemical reaction reaches equilibrium when stable, and thus a human body should be stable when there is no ‘lost energy’ and the system has the ability to apply strength to its fullest capacity.
Strength:  The application of force.  Also simple and in my opinion the only factor amongst these four which is absolutely necessary. Absolute strength is quite different to specific strength, and we can really only test very specific strength. For example 1 RM testing depends on a lot of coordinated movements to occur in the right order, not necessarily on absolute strength. To that end, I don’t think the concept of ‘strength’ is quite done developing yet.
Flexibility:  Flexibility refers to the absolute range of motion possible within a joint or series of joints and may be either static or dynamic (Ref). This depends on pretty much every kind of tissue you can imagine surrounding and within the joint.

How do you see the interaction of these leading to increase performance?
A very common, applicable reductionist approach is the mobility, stability model of athletic performance (Ref).  Although this is a very useful paradigm to use, it is important to note that more mobility in particular areas may not enhance athletic performance. It may not be functional to the athletic endeavour to garner incredible amounts of ankle range of motion to enable sitting into a deep squat if an athlete cannot control their lower kinetic chain enough to hop and land. In fact, authors have importantly ensured this model remains only a thought model to guide regular strength training practices (Ref). These constructs obviously impact on the skill being performed, and in my opinion they are interdependent.  These constructs must be considered together and an ideal balance between the three factors within the individual must be appreciated in order to perform the skill to its fullest capacity.


​Strength is an integral component to any high-performance scenario. I think of strength as a vector moving through the ‘playing field’ of flexibility, mobility and stability. We can appreciate that enhancing strength in the wrong direction can be the difference between adding strength to a system which will never be efficient enough to apply any force properly (i.e., too much stability or too much flexibility). Whereas strength applied in the right direction can ensure strength is applied very efficiently and no force is lost. So just adding strength, without consideration for the requirements of the individual is like putting more load on an inefficient system
flex, mob, stab 2 fullsizerender_origFlex, mob, stab fullsizerender-2_orig

How do you see the interaction of these leading to rehabilitation?
I don’t see a huge deal of difference, in fact strength generally becomes more important. The integration of mobility, stability and flexibility needs to be assessed before undertaking strength training principles. Athletic injuries and injuries in general are incredibly hard to predict but following an injury, it may be possible to ascertain why they occurred and what mix of flexibility, mobility and stability may have gone wrong. This would give you a head start in rehabilitation, a good assessment of the ‘playing field’ and ‘direction’ you need to move in is of prime importance.

Not everyone needs more flexibility and not everyone needs more stability. In the experienced clinician’s practice, this model happens automatically and is simply intrinsic to successful rehabilitation. In my experience, mobility is increasingly included in ‘early motor control’ in rehabilitation contexts (Ref). Mobility is an important concept to keep in mind in rehabilitation, but I think it’s important to note that not everyone needs to go through mobility first and then onto stabilising joints that you have just made ‘mobile’. Instead of going through this as a matter-of-fact, an assessment of what exactly the athlete needs in particular scenarios is important. Mobilising an ankle to enable a lower squat may make it easier to program squats into your rehab, but will this new-found range lead to issues when the athlete has to put everything back into their specific skill again?

Progressing from closed to open skills and into game-play is what is done currently, and when done successfully I would propose it is, essentially moving in the ‘playing field’ in the right direction toward the green light again. More thought as to what mix of mobility, stability, flexibility and strengthening may lead to simply less ‘doubling handling’ of needless (mobility, stability or flexibility) practices.

Hear me now.. This is a tight little diddy for your ears. Enjoy any of this guy’s stuff actually, it’s all good.

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