This was an important lecture for me as it introduced several concepts that prompted me to study many important aspects of skill acquisition as I mentioned in my introduction to What is good coaching?
Frans Bosch is professor of biomechanics and motor learning at Fontys University for Applied Science in the Netherlands and sprint consultant to the Welsh Rugby Union – you can read more about him here. My notes, in bullet point format, from the lecture are below:
- The laws of motor learning should be central in designing a strength program rather than Newtonian laws
- In order to maximise the learning result Strength exercises need:
- Precise intention
- Variable execution
- Basic motor properties such as strength, endurance, flexibility, co-ordination etc don’t exist
- This is because there is no clear dividing line between properties – there should be a guaranteed transfer of that property between movement patterns but this is not the case
- A well trained high jumper can get Maximum Voluntary Contraction to 95% executing a high jump (compared to an untrained person’s level of 75%) but they couldn’t do the same in a Javelin throw as it is a different movement pattern
- If muscle is not pre-tensed in an isometric contraction prior to movement then it has slack
- Up to 50% of a countermovement jump, for example, can be taken up with the muscle going from slack to taut
- Resistance exercises like a barbell hang clean provide pre-tension for the muscles through the weight of the barbell providing a counterbalance
- This results in the body becoming lazy as regards pre-tension – Frans has eliminated countermovements from lifts for his athletes for this reason
- As a result strength cannot be considered a stand-alone bio-motor property and classic mechanics do not address motor control and is too reductionist an approach
A more in depth explanation of the concept of muscle slack is provided in this article
Frans’ Rules of Specificity as the main requirement for transfer
- Types of muscle action must be similar to those used in competition (Inter/Intra muscular)
- Structure of the movement must resemble that used in competition (motion of limbs)
- Sensory information must resemble that present in competition
- Dominant energy systems used in competition must be called on
- Result of the movement must be the same as competition
- 1& 2 are the usual suspects – 3 is a key factor often overlooked. Frans did not mention in his lecture but this is due to perception-action coupling which I mentioned in my blog What is good coaching? Two papers of interest on this are here and here.
- Focussing on a movement outcome produces a better learning effect than focussing on performance of a skill
- Frans detailed a study that split discus throwers in to 2 groups that received feedback from:
- An elite coach – giving them Knowledge of Performance (KP – how well or poorly they executed the throw)
- A measuring tape i.e. they were only told how far each throw went – giving Knowledge of Results (KR)
- Those in the Knowledge of Results group attained results as good as those receiving feedback from a coach in the short term and performed better in the long term
- KP results in an internal focus for athletes where they are thinking about where to position their limbs, sequence of movement which can result in overload (otherwise called reinvestment) and poor performance
- KR leads to an external focus whereby the athlete is only thinking of achieving the goal
- Therefore a Clean type movement is better than a High Pull as it has a clear outcome goal where the bar is racked on the shoulders
I emailed Frans to ask about the study he mentioned and it was by Ballreich but pre-digital era and he only had a hard copy. The Wulf and Prinz Review mentioned on the slide is here.
Dynamic Systems Theory
- There are many differences in running between an elite track sprinter and an elite rugby player such as more trunk lean and lower heel recovery height for the rugby player but how relevant are they?
- Degrees of freedom – the number of parameters that may independently vary – click here for more info on this and here for a study on free(z)ing DoF
- In the arm there are 1,000’s of degrees of freedom through the various joints & muscles
- Too many degrees of freedom can make control impossible therefore the body seeks to stabilise certain elements that then serve as attractor wells for the unstable elements (see pic on right)
- We start with relatively unstable technique but as certain key elements stabilise they increase the depth of the well they sit in which attracts the unstable elements more easily
- Skilled practitioners show a high variance in movement patterns that are repetitive
- E.g a Blacksmith hitting an iron will have a different start position each time but hit the same end position each time – based on work of Bernstein (who interestingly coined the term “Biomechanics”)
- Therefore we should look to address 2 or 3 key attractors for a skill that are always the same rather than try to address every facet
- E.g a Clean that finishes with a single leg up on to a step has the same attractors as running and the fluctuations (differences such as knee lift heights) are irrelevant
Decentralised Self Organisation
- The body tends to be variable but the implement it is using or outcome it achieves is very precise
- There is no hierachy of top down, brain to muscle signalling
- The whole system is involved throughout a movement correcting errors as it develops (decentralised self organisation)
- As the signal is filtered down through the system noise is fine tuned to remove errors
- A squat in the gym has no pertubations whereas sport has many due to the chaotic nature
- As a result instability in training (weights and surfaces) is very important due to the theory of differential learning
- Aiming for perfect technique in a stable environment (e.g. back squat in a gym for a rugby player) does not improve competition performance whereas strength training that has variable performance in an unstable environment does
- Learning a skill is not learning a perfect technique but learning how to correct errors
- Therefore instability and variation in strength exercises are crucial for the learning effect
This lecture rattled a few cages from what I heard other delegates saying afterwards. As Ian King often says, there was an immediate over-reaction followed by a long term under-reaction on this as many came away thinking Frans was saying all strength training must be done on one leg on a upturned BOSU and therefore they would ignore what he presented.
I had my own opinion on the main point of the lecture and fortunately managed to corner Frans afterwards to clarify this. It is important to note the difference between General Preparation Means and Specific Preparation Means. The article by James Smith, classification_of_the_means, does a good job of explaining these classifications. Once this is understood you can see that transfer is only really a consideration for Specific Preparation exercises.
Frans was not saying that all strength training must be done on unstable surfaces and every exercise must be on one leg etc. He was saying that within a program you must take in to account the fact that sport is chaotic and in order to properly prepare for this these are important considerations. He is a consultant to the Welsh Rugby Union and it is clear that their players are not waving 2.5kg dumbbells around sitting on Swiss balls all the time. They do traditional strength training as part of their General Preparation but also incorporate these methods around Specific Preparation such as speed and sport training with great success.
I think certain delegates (not all I hasten to add) missed the key messages surrounding motor learning and skill acquisition. As with most things in life, there is a blend of many factors necessary for success yet people are keen to polarise debate where this does not in fact reflect reality.
I personally found this lecture fascinating and it directed me to many interesting topics within skill acquisition which I feel are now benefitting me greatly.
