Why is it so difficult to learn the snatch?Implications for coaching

Chris Hattersley – MSc, CSCS, CESemail: hattersley4@hotmail.co.uk

Twitter: @hattersley4

Overview

• Discuss the complexities of the snatch from a motor control perspective.

• Review how learning occurs at each level of the motor pathway and show how the different sub-systems involved interact.

• Offer suggestions for how the snatch should be taught.

• Discuss different types of teaching as well as session structure.

Pyrros Dimas – Snatch Video

https://www.youtube.com/watch?v=SgCxxhaIt2s

Snatch – Motor Control

• Closed skill, no reactive or perceptual component. • Co-ordinated activation of all muscles in the body• High amounts of neural drive, rate coding, inter

and intra-muscular coordination.• All carried out within < 1 second!

• Extremely challenging for the nervous system to coordinate this.

(Stone et al, 2006)

Key Principle of Neuro Science

• ‘Cortical area is representative of the amount of circuitry required to perform a specific task’

• Areas involved with movement are much larger than the ones for maths and language.

• Movement is the most difficult task performed by the body.

(Kandel et al, 2012)1414 pages

The brain and movement

The brain has to co-ordinate nerve impulses through all the motor areas during the snatch.

Motor Homonculus• This depicts the amount of circuitry

within the motor cortex designated to each part of the body.

• Areas with smaller MU’s and more refined movements require more circuitry.

• During the snatch the motor cortex must synchronise nerve impulses through each of these areas.

• (Schott, 1993)

Sensory Homonculus• Located at the front of the parietal

lobe.

• Processes information on spatial awareness and the planning of movements.

• Depicts the amount of sensory circuitry designated for each body part.

• Not as disproportionate as the motor homonculus.

• (Schott, 1993)

Cerebellum• Densest neural structure in the brain,

80% of the brains neurons are located there! (Herculano-Houzel, 2010)

• Detects ‘motor error’ between intended and actual movements.

• Involved in co-ordination and timing of fine motor tasks.

• High potential for motor error during the snatch as the inputs from higher and lower centres are initially incorrect.

• Initial movements will be jerky and poorly timed until the appropriate neural pathways are built in the cerebellum.

Spinal Cord Circuitry

• The spinal cord receives both descending and ascending inputs.• This is happening at every level of the spinal cord, with every muscle in the body.• Heavy snatch involves full activation of motor pool(Pierrot-Deseilligny & Burke, 2012).

Reflexes / Pattern Generators

• The spinal cord co-ordinates how nerve impulses are sent to the muscles.

• Pattern generators integrate this feedback and ensures rhythmical movement of muscles and limbs.

• Ensures muscle are activated at the right time in a smooth manner.

• Processed in the grey matter within the spinal cord i.e. Motor neuron pool

• Pattern generators ensure both limbs are activated at the appropriate time during the snatch.

(Enoka, 2008; Zehr, 2005)

Integration of Subsystems

(Bosch, 2012)

So…..

• A novice cannot accurately calculate and coordinate the muscular contractions needed to execute the snatch efficiently.

• These circuits have a high amount of plasticity and therefore movements can be learned and refined with coaching.

Implications For Coaching

Demonstration• One of the most fundamental types of coaching.

• Observational learning theory (Bandura, 1977).• Visual perception perspective (Newell & Scully, 1985).

• Shows why we adopt or replicate the movements of others.

• Weaknesses, only discusses why demonstration might be beneficial from a social and behavioural change perspective rather than biological.

• Possible neurological adaptations to this?

Demonstration• It is widely accepted that a shared neural circuitry exists during

imagery and when performing a skill (Decety, 1996).

• A similar process happens when viewing the behaviour of others.

• This is termed the mirror neuron system (Rizzolati & Craighero, 2004).

• When watching a task the areas within the brain involved with that task are activated (Rizzolati & Craighero, 2004).

• People with autism lack this system, reducing there capacity to learn social and motor skills (Rizzollati & Fabbri-Destro, 2010).

Mirror Neuron SystemImage A. Brain activity when viewing static images of ;• A face • A hand• A foot

Image B. Brain activity when viewing videos of;• Biting an apple and chewing• Reaching and grasping for a ball with

the hand• Kicking a football

• Parietal lobe activity in Image B. shows the participants are working out how to move there body in the observed way.

Red = Face, Green = Arm, Blue = Hand. From Buccino et al, 2001.

Video Feedback• Video is an objective method which can be used to monitor performance

and deliver feedback (Wilson, 2010).

• Variety of angles and speeds.

• Rucci & Tomporowski, 2010 - Compared, video + verbal feedback, verbal feedback only and video only on 4x4 hang clean over 6 sessions.

• Video + verbal feedback and verbal feedback significantly improved.

• Knowledge of performance is more beneficial than knowledge of results.

• Need to develop there own unique movement pattern, rather than imitate.

Verbal Feedback

• Instruction provides explicit cues before a task.

• Feedback is information provided after a task.

• Can vary how much feedback is provided and when.

• More general for a novice, specific for advanced.

• (Hebert & Landin, 1994)

Organising Practice

• What structure to teach in i.e. reverse chain

• More than one skill at a time?

• Blocked, serial or random?

• Errorfull or errorless environment?

• Depends on the individual and the stage of learning.

• (Starkes & Erricson, 2003)

Stages of LearningStage of Learning Type of Training

CognitiveLots of instruction / feedback

Partial lifts, rev chain

Lots of demo’s Emphasis on blocked

Practice in low reps Errorless

AssociativeLess feedback, more constraints

Partial & full lifts

Less demo’s Introduce, serial & random

Increase practice time Mix errorless & errorfull

AutonomousSpecialised feedback / video analysis

Full lifts

Increase load Emphasis on random

The model is flexible and should include small amounts of each type of training during each stage of learning, while also catering for individual learning styles.

Conclusions• The snatch is a highly complex movement pattern

which requires a lot of time to perfect.

• High quality demonstrations and video feedback are necessary but verbal feedback and cues from an experienced coach may be more important.

• Different types of teaching and session structure should be emphasized at different stages of learning.

Any Questions

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