As practitioners we are all essentially coaches, and in our various realms we find ourselves directing athletes on how we want them to move. In the first part of this 3-part post we delved into the why, as we attempted to elucidate what roles we should play, and define what objectives we should be seeking to fulfil when providing instruction to athletes. With this second part on coaching movement we get into the 'what'.
As we do so, we must first account for the fact that 'athletic movement' is itself nebulous, encompassing as it does a variety of different actions, which can take multiple forms, expressed in a range of different scenarios. The various facets of athletic movement comprise a host of perceptual-motor skills that athletes must acquire and refine in order to train and compete successfully in their sport.
In a previous post we attempted to define 'athleticism', and in doing so identified ten pillars, one of which was 'mastery of fundamental athletic movements'. To help define 'athletic movement' we might therefore employ an inclusive list of fundamental motor skills that are common to sports, such as gait/locomotion, jump/land, squat, lunge, balance, throw, catch, push, pull, twist/rotate, and pivot. Essentially athletic movement skills comprise a selection of these component skills in some combination, expressed in the context of the sport, and executed in a training and competition environment.
FINDING THE PATH…
Motor learning and skill acquisition are nonlinear processes. The timelines and trajectories for these processes are also highly individual. By extension, the processes of instruction and coaching can also be considered to be nonlinear, and will be similarly dependent upon the individual.
@@The journey for each athlete will necessarily be different in each instance@@. Each athlete represents a different puzzle to solve. Indeed the same athlete at different times in their career may present as a different puzzle.
Our role is to find the best path for each athlete as we figure out the puzzle with them, and provide guidance as they work through what is essentially a problem-solving exercise.
From these considerations it quickly becomes clear that it is not about trying to find the full-proof system, ‘best method’, or the magical cue. We should instead strive to acquire a sound grasp of governing principles; we can then apply these principles to the situation in front of us, and select methods accordingly.
SOME ASSUMPTIONS…
As we scrutinise traditional approaches to instruction, it seems that there are certain assumptions which underpin what is commonly practiced when coaching movement.
Firstly, it is strongly implied that there exists a stereotypical ‘ideal’ technique, and that this should serve as our template when instructing and coaching. Oddly, it is rare for us to question the notion that there is one ‘correct’ or textbook way of executing the given athletic movement skill. Is the idea of a single universal solution for all athletes plausible?
Perhaps we might allow that the best way will differ somewhat according to the individual. However, this still assumes that there is only one ‘best way’. Should we really only coach one solution for an athletic movement?
Conventional wisdom in relation to coaching and skill acquisition also leads us to believe that with learning things become more grooved, so that motor performance becomes more consistent and less variable. By extension, it is assumed that skilled performers can be expected to show very little variability in their motor patterns, as the motor skill becomes more automatic and reproducible. But is that actually the case?
ON CLOSER INSPECTION…
When we closely observe highly skilled performers executing the ‘same’ closed skill it becomes apparent that successive repetitions of the movements are never actually identical. This phenomenon was famously termed ‘repetition without repetition’ following the pioneering work of Nikolai Bernstein.
Skilled athletes are able to produce a highly stable outcome (task performance) via a multitude of different actions. These different actions range from subtle variations of the primary solution to entirely novel improvised solutions.
This realisation has led some authors to introduce the notion of 'good' variability (flexible, adaptive) versus 'bad' variability (adverse outcome, higher potential for injury). Whilst this is an oversimplification, the mere fact that variability is becoming acknowledged as integral to skilled performance and skill practice nevertheless represents a major step forwards.
LEARNING IN PRACTICE...
“Practice is a form of exploratory behaviour, a continually evolving search for task solutions”
There are some key elements in this description of skill practice that merit attention. The first is that exploration is integral to the process of acquiring and refining athletic movement skills. By extension, @@the athlete should be afforded an opportunity to explore the boundaries when executing the task@@, and engage in some trial and error as they practice.
A second important theme is that solutions are constantly evolving. It is also worth noting that we are talking about solutions plural. To that end, the athlete should be trialling multiple solutions, or ‘families of solutions’, for the ‘meta-stability’ this offers.
There is generally more than one way to do something. Moreover, the athlete will be faced with different constraints and conditions that will necessitate being able to achieve the same outcome via different means. On that basis, if we apply only provide one solution, even if it a really good solution, we are not adequately preparing the athlete to perform under different constraints and conditions.
STABILITY AND FLEXIBILITY...
The hallmarks of athletic skill include not only the ability to produce a stable performance outcome, but also the capacity to demonstrate flexibility in how that outcome is arrived at. Skilled movers are equipped with multiple options; in essence they are able to bring different solutions to the same problem.
“...not fixed into a rigidly stable solution, but can adapt movement coordination patterns in a functional way, as a function of system degeneracy… perceptual motor systems are stable when needed, and flexible when relevant..”
Defining skilled performance in this way contrasts to the notion that ‘athletic skill’ is simply the ability to repeat a single stereotyped, choreographed, and well-rehearsed ‘textbook’ action that has arbitrarily been deemed to be ‘correct’.
There is redundancy both in the motor system, and in the majority of motor tasks. This fundamental property gives rise to the concept of ‘equivalence’, whereby multiple solutions or ‘families’ of solutions can be employed to achieve an equivalent (i.e. successful) task outcome, just in different ways.
A major benefit of possessing a bigger bandwidth for solutions is that performance hereby becomes adaptable to different task conditions and robust to ‘perturbations’. Having a repertoire of solutions provides work around options to ensure we can still get the job done regardless of the circumstances. With flexibility comes the ability to improvise when faced with unexpected constraints or obstacles.
PHYSICS TRANSCENDS PHILOSOPHY…
In learning and coaching there are few universal rules. However, one exception is that the physics of motion apply universally to all athletes, regardless of their capabilities and the peculiarities of the sport.
As practitioners we must also recognise that physics equally applies irrespective of the discipline we happen to work in. @@Physics has zero regard for our philosophy, coaching model, sport, status in the field, or reputation@@. Be assured; if you attempt to violate the laws of physics, physics will violate you.
Newtonian laws of motion apply to terrestrial motion, so this seems a good starting point when coaching athletic movement. During running and jumping activities the athlete’s body is essentially a self-propelled projectile. When coaching these athletic movements we therefore need to consider projectile motion.
Specifically, projectile motion stipulates that displacement (how high, how far, and in what direction) is determined by velocity at release or take-off, which in turn is dependent upon the magnitude and direction of the impulse of force imparted to the ground (which is then returned to the body to produce movement). The athlete’s own body has inertia; hence it is the magnitude and direction of the impulse applied to the ground relative to their body mass which is important in determining take off velocity (and hence displacement).
Bear the physics in motion we have just discussed in mind; it will be important as you read the following section…
ALIGNING AIMS ON INJURY AND PERFORMANCE…
As pointed out by a recent publication, investigations of 'safer' movement strategies in the sports injury prevention literature do not necessarily acknowledge the impact the particular intervention might have on athletes’ performance. If what is being advocated is likely to impair the athlete’s ability to perform, this is pertinent information that needs to be disclosed, and something that as coaches we need to take into account.
Inevitably if the recommended strategies and interventions are not congruent with performance outcomes this presents a problem. We cannot realistically expect athletes to comply with something that negatively impacts their ability to effectively perform the athletic movements required by their sport.
An illustrative example comes from a couple of studies from one research group which have proven very influential among physiotherapists and those involved in the injury prevention realm.
See if you can follow the logic. The more lateral the foot placement when changing direction, the larger the moment arm for vertical forces acting on the lower limb, and hence the greater the abduction moment at the knee. Similarly, if more force or impulse is applied at the foot then larger forces are transmitted through the lower limb kinetic chain, which might increase the strain on joint structures and thereby the potential for injury.
Based on this reasoning the authors advocated a two-fold strategy for ‘safer’ change of direction. Firstly, foot placement should be more narrow – i.e. more under the base of support, in order to reduce the moment arm. Secondly, the authors recommended a softer foot contact, so that less impulse is applied at the ground and transmitted through the chain.
Clearly, this was well meaning, and on the surface the reasoning might appear sound. Sadly, it does also violate the physics of what we trying to do.
Returning to our discussion on the physics of motion, any change in velocity is determined by the magnitude and direction of the impulse of force applied. The magnitude component is relative to the mass and inertia of the athlete’s own body. The direction part needs to consider both the orientation of the force vector in relation to the desired direction of motion, and the location of where force is applied to the ground in relation to the athlete’s own centre of mass.
Given that change of direction activities are typically executed whilst in motion, we need to consider the athlete’s own momentum (both magnitude and direction), so the impulse-momentum relationship also applies. Essentially the greater the change of direction, and/or the higher our speed when executing the change of direction, the larger the magnitude of impulse of force will need to be.
What this means is that advocating a soft foot contact when attempting to change direction contradicts the physics of what is demanded by the task of changing direction.
So let’s now consider the narrow foot placement part. In order to change direction we need to direct the impulse of force imparted to the ground in the right direction. By definition, if we want to move in a lateral direction the foot placement must be outside of our centre of mass in a lateral direction, so that force is applied rearward of our centre of mass with respect to intended direction of travel.
What this demonstrates is that @@each part of the dual-pronged strategy advocated for safer change of direction (i.e. more narrow foot placement, soft foot contact) violate the physics of what the task requires@@.
Effectively, what we are saying is it is ‘safer’ to continue running in roughly the same direction. In fact to make it safer still we will also slow down by employing gentler foot contacts.
Taking this risk management approach to its logical conclusion, really in order to be most safe we should recommend that the athlete just sits down… on the bench. After all, if they are not in the action, they can’t get hurt.
In fact, maybe they should sit in the stand… although not too far up in the stands, lest they fall down.
MECHANICAL EFFICIENCY (AND EFFECTIVENESS)…
As illustrated in the previous example, we cannot lose sight of the effectiveness of the strategy or solutions we are steering the athlete towards. We cannot get away from the essence of the task and our objective. The task when changing direction task is straightforward – the shortest distance between two points is a straight line, and our objective is to cover this distance in the shortest time possible.
Let us return to the wisdom offered by Dan Pfaff that as coaches we should be continually striving to improve mechanical efficiency. It is demonstrated that more mechanically sound technique during locomotion enhances economy and thereby performance. Employing more mechanically effective and efficient movement strategies is likewise reported to reduce the stress placed on the system, emphasising the missing biomechanical link in the resilience to training load discussion.
Using the lens of mechanical effectiveness and efficiency thus unites both performance and injury risk management objectives.
IN CLOSING...
It seems logical that physics should govern our approach when coaching athletic movement. Sadly, common practice in the realms of sports science, sports medicine, and sports coaching is more driven by convention and dogma than we like to believe. On that basis, we cannot assume that what is advocated or employed in practice necessarily considers or adheres to the fundamental physics of the task.
Following the first part we now have a grasp of the 'why', and herein we have discussed the 'what', so with the forthcoming final part of the series we will get in the 'how'.
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