How Coaches Analyse Skill
Rowden Fullen (2002)
- Systematic approach to skill analysis
- A. Pre-observation phase
- 1. Factors affecting the ability to observe movement
- 2. Development of an observation plan
- B. Practising observation skills
- C. Diagnosis
- D. Remedial action
Advanced technology has provided the means for the coach to gather very accurate information on the performance of his players. Video-cameras are now used extensively both in training and competition to record exactly how the player is functioning, so that the coach can assess areas such as technique and tactics, with the purpose of improving overall performance. While such tools do much to improve understanding of exactly how movements are executed, the analytical tasks faced by the coach are still predominantly qualitative in nature and he is still faced with an incredibly complex task.
Equipped primarily with his knowledge of the skill and his own qualities of perception, the coach is expected to observe and analyse his player executing many complex and extremely rapid movements. Using these observations he is then expected to make instantaneous decisions in respect of skill techniques and provide effective feedback to his player. All this ‘action’ happens frequently in time periods of as little as a fraction of a second up to one to two seconds! While there is no doubt that the experienced coach is able to do this extremely well, there is also no doubt that many others in our sport identify performance deficiencies using a trial and error approach.
To expose errors and correct these are the ultimate goals of skill analysis. Qualitative analysis offers a systematic approach to achieving such goals. While the approach is based on the knowledge of mechanical principles, it also requires acute and organized observation and diagnostic skills. The coach must also be aware not only of constraints on his player’s performance but also of limitations in his own processes of perception and observation.
Systematic approach to skill analysis
Accurate error detection and ensuing correction require an ability to systematically observe and analyse performances. A systematic approach involves 4 major stages — pre-observation, observation, diagnosis and remedial steps. Figure 1 represents a model of a systematic approach to skill analysis.
The pre-observation phase includes two stages which must be tackled first, prior to observing and analyzing the skill performance. The first, movement analysis, focuses on the identification of the critical features. This is followed by the development of an observation plan.
The observation phase is concerned with the actual study of the skill, the attention to visual stimuli.
In the diagnosis phase differences between the desired and the actual (observed) performance are identified. The coach reviews these differences to determine the primary and secondary errors.
During the remedial stage the coach will reflect on the performance errors, then formulate a remedy — a correction. His feedback and suggestions to the player will be based on this formula.
A) PRE-OBSERVATION PHASE
Basically this involves visually and mentally breaking down a skill before actually attempting to observe it. Many advanced coaches already have in their mind a sound concept of the basic components of a particular skill, built up over years of experience of coaching players, lecturing to coaches or preparing and writing coaching material. However the ability to analyse and provide effective feedback is dependent upon the accuracy and relevance of the coaches’ observations. Coaches cannot possibly examine technique if they are unaware specifically which components determine effective performance and how best to observe them.
Pre-observation preparation may require a little time and effort, however it is a precursor to accurate observations and analyses and does become much easier with practice. It is also noticeable that coaches originating from countries which are strong in ‘formal’ coaching development, often have a rather better base for assessing what makes up technique as this forms part of their early development. Coaches from countries where training development is more informal or players who have been transplanted into coaching often find much more difficulty in this area.
The pre-observation phase is divided into two steps — the movement analysis and the observation planning stages. The movement analysis stage culminates in the identification of the critical features, while the purpose of the observation planning stage is to design observation plans and decide how to record these. A diagram of the movement analysis stage is shown in Figure 2.
Figure 2 The movement analysis stage
|Step 1||Determine performance criteria|
|Step 2||Simplify performance criteria|
|Step 3||Determine mechanical components|
Target Goal : Identify critical features.
The critical features are the components of the movement that are essential to the performance of a skill. Coaches interested in improving the technique of their players must focus on these critical features during their observations. For example a back-swing is required in a topspin stroke in order to develop maximum racket speed. This component of the movement is critical and its absence or malfunction will prevent effective performance. Critical features are observable, mechanical quantities such as impetus and momentum are not. However where you have movements such as long arm action or fast rotation of the body during a stroke, although these may indicate that impetus or momentum has been produced, they are also patently discernible – therefore they are critical features.
Adaptations within a given technique.
Although critical features are inflexible parts of a movement they are often modified by individual differences. Within a given technique a performer may use individual modifications such as unique timing or sequence of movements. These unique and individual adaptations are called style. The use of a circular wind-up for a forehand stroke is an example of an individual adaptation. This is not a component of the sequence of movements that is critical to the outcome of the skill. Conversely, the movements performed during the approach and ball contact stages are examples of critical features. They must be performed correctly in order to achieve the best results. Optimal technique refers to the most efficient performance of a movement pattern within the constraints and requirements of the skill or activity.
Identifying critical features.
The identification of the critical features is a far from simple task. It requires a broad knowledge of basic mechanical and motor concepts and an ability to apply this information to different types of movements. The following process can assist in pinpointing the critical features for differing skills. The 4 steps serve to channel and focus the coach’s analysis in a logical and systematic manner, by developing a mechanical model for each skill.
- Determine the performance criterion.
- Break the skill into smaller parts.
- Determine the mechanical factors affecting performance.
- Identify the critical features.
The first step in the development of a mechanical model is to clearly identify the performance criterion — the exact purpose or goal of the skill. In other words what is the intended result of a successful performance of the skill? How is it measured or evaluated in a competitive situation? Is it measured objectively or subjectively?
Often subjective skills can be evaluated on the basis of their contribution to the point or game. Coaches must determine whether or not the skill was performed to best advantage. The purpose is then expressed as an advantage and this purpose is dependent perhaps on spin, speed or placement, or some combination of these.
The second stage is to simplify the skill for analysis by breaking the movement down into parts or phases. Frequently skills may be divided into 5 phases and this break-down process allows the coach to examine the mechanics which affect specific components or parts of the skill.
- Preliminary movements.
- Back-swing or recovery.
- Force producing movements.
- The critical impact instant.
- The follow-through.
Once the purpose of the skill has been identified and the skill sequence simplified into parts, the coach is ready to determine the mechanical factors affecting each component or phase of the skill. Remember that technique is largely determined by mechanical factors. This stage of the process is the most difficult as it requires the synthesis of all fundamental mechanical principles. This movement analysis stage should be considered as the homework phase of the whole analysis process — take time over it. Systematically determine the mechanical factors for each part of the skill. These mechanics do not change, so once you have them figured out, your work on this step is complete. Many experienced coaches have for instance a mental check-list of exactly what to look for at this stage in the analysis.
Once the mechanical factors have been determined, the critical features may be identified. Critical features describe specific body movements — we are looking for an indication of whether or not the mechanical factors have been executed ideally. Force is not observable but we can watch for specific body movements, quick straightening of the legs, strong body rotation, fast arm movement, all of which indicate that force is being generated.
1. Factors affecting the ability to observe movement
Coaches should be aware of possible external and internal distractions and try to recognize, eliminate and/or minimize these. The ability to observe and selectively attend to the most important parts of a skill is fundamental to effective coaching. The observer’s needs and interests, as well as the competitive and/or coaching environment, will affect what attracts their attention — possibly resulting in a reduced focus on the critical features of the performance — and subsequently how they interpret their observations. The factors affecting the quality of observations made can be divided into three groups — internal distractions, external distractions, other physical or environmental constraints.
Internal distractions — Different sources include motivation, fear, excitement, observer bias and expectancies and lack of an observation plan. Coaches must be careful to remain objective and not to ‘see things that aren’t there’. It’s also important not to jump to conclusions, what is present in one skill execution may not be there consistently — examine the consistent traits.
External distractions — The more intense the colour and the larger the size, the more an object will attract attention, as will sharp contrasts. Extraneous movement attracts attention and a certain amount of ‘visual discipline’ is required to focus on specific movements, when other activity is in view. It is more difficult to observe very fast or very complex movements, often it is better to scan the whole movement from afar and then move in to focus on specific parts. Our eyes also tend to scan best from left to right and rapid movements are best observed from a vantage point which allows left to right viewing. The type of surroundings, lighting etc. may affect our ability to concentrate on specific body movements.
Other physical or environmental constraints — Coaches need to consider their own influence on their player’s performance during their analysis. Other constraints may be physical, body structure, limb length, vision - physiological, power and endurance, flexibility or cardio-vascular conditioning — mental, not motivated — or characteristic of the event, equipment conditions, playing surface, or temperature.
2. Development of an observation plan
Observers who try to see everything often end up perceiving nothing. Movement observation must be systematic in order to be effective. The development of an observation plan answers how, when and where to observe. Coaches who approach observation haphazardly will be unable to selectively attend to and record performance of the critical features. They must be able to methodically search for the relevant features of a performance. Each observation plan is designed to relate to a specific task such as a coaching session, which focuses specifically on actions involved during the force production phase or the follow-through phase of a stroke. What is most important is not how you plan but that you do plan.
Developing the plan.
There are 4 steps involved in the design of an observation plan.
- Identify the observation task and select the relevant critical features.
- Determine the appropriate observation strategies.
- Determine the number of observations required.
- Select the positioning strategies to gather the identified information.
1) There is a limit to our ability to observe and accurately record the movements of the human body. Coaches need therefore first to identify the goal of the observation session. It may be to improve the movements in a particular part of the skill, or it may be to refine the skill as a whole. Critical features previously identified in the movement analysis phase are re-examined and those features relevant to the observation session are selected.
Consider for example the critical features which we may identify in the case of the forehand topspin. If the focus of the particular coaching session is to improve the actions which occur solely with the racket arm, then we only need to select for observation the critical features which are relevant – the amount of back-swing, the speed of back-swing, the length and plane of the arm, the speeds and application of the various parts of the arm, the force producing movement, the contact point in terms of time and place, the angle of the racket at contact, the optimum area of contact on the racket and the follow-through of the arm. We need not concern ourselves with the critical features relevant to leg movement or rotation of the body. The selection in this way of a sub-routine of relevant critical features will greatly simplify the observation process.
2) Observation strategies are formulated after consideration of the following questions.
- What is the best way to observe the critical features — focusing or scanning?
- On which parts of the body or the environment should the coach focus or scan?
- Are there some critical features which need to be observed simultaneously?
3) The number of observations needed to obtain all the necessary information is dependent on the skill. Each repeated observation should be used to view some particular aspect of the movement, so that by the final observation there is a clear record of exactly what has happened. Throughout coaches must look for consistent characteristics of the player’s performance — the absence/presence of one critical feature in one repetition is fine, but what’s important is if this characteristic is consistent. The effects of fatigue on performance may also need to be considered if observation lasts for some time. The pre-observation phase helps prepare the coach to capture the essential elements of performance as efficiently as possible.
4) If the vantage point is not considered, other observation techniques may be useless. The optimum position to view varies from skill to skill and from feature to feature. The position of both the performer and the observer determine what can and what cannot be seen. Many inexperienced coaches have no recollection of their positions or remain in one spot all the time. Determining how to observe from the right place and at the right time to be sure to collate the relevant information requires serious thought and practice.
B. PRACTISING OBSERVATION SKILLS
Practice is needed to perfect observation skills and to obtain an accurate record of what was actually observed. Initially it is better to record observations manually. One method is the use of a checklist which can be ticked off as you observe. Some coaches even bring with them a complete movement break-down and observation plan, which clearly indicates how, why and when they will observe each of the selected critical features. With practice and as different components of the analysis become absorbed mentally, coaches can develop and apply a plan in which the observation of the critical features is mentally recorded.
Observation strategies – hints.
- It is often best to scan first to get a general impression of the performance before focusing on the critical features. It should be noted however, that if a coach attempts to get a complete over-view of the whole movement sequence, it is unlikely that he will get a detailed picture of any individual part of the movement.
- The speed of the movement often increases from the centre of the body out to the extremities. It is difficult to see rapidly moving extremities or striking implements such as rackets. Movement observation can be simplified by looking at slower moving parts first.
- Focus on a given movement or combination of movements long enough to visually capture it and later describe it.
- Scanning for a range of motion in various body parts may help to assess skills in which speed or impetus is important. Move round during the observation process. Different positions provide differing information regarding the critical features.
- In general the best vantage point is one that is at right angles to the plane of motion.
- Move far enough away to overcome problems associated with the speed of the performer moving across the observer’s field of sight.
- When movements extend over some distance, the best vantage point is opposite the midpoint of this distance. The observer must be far enough away to see the entire sequence. However when focusing on the smaller components of the movement, the observer should be quite close to the performer.
- When attempting to observe at tournaments or in large busy areas, try to select the best vantage point in terms of minimizing external distractions, while still having the best possible view of the performance.
The purpose of the diagnostic stage is to identify primary errors, as this is a pre-requisite to making corrections and improving performance. A primary error is one which is the main problem and must be corrected before improvement in performance can take place. (Secondary errors too are important, as they may provide important information concerning the primary errors.) For example to spend time trying to speed up the racket arm when there is inadequate back-swing, is a waste of time. Too short or too slow a back-swing inhibits the quality and efficiency of movement and inhibits the full utilization of elastic energy — either is a primary error. An accurate identification of the primary errors must occur before making corrections to improve performance.
The starting point in identifying primary errors is to note the differences between the observed and desired performance of a critical feature. Next the coach needs to make informed decisions as to the causes of these differences. These decisions are based on a knowledge and understanding of the basic mechanical principles.
- Recognize difference between observed & desired performance
- Identify errors
- Identify primary and secondary errors
The actions which cause the differences between the observed and the desired performances are the primary errors and are what the coach needs to address.
D. REMEDIAL ACTION
Once the primary error or errors have been identified a prescription is decided upon — a method of correction. It may be necessary to design appropriate exercises, at appropriate speeds to improve the technique.
Suggestions which may assist in the diagnosis of primary errors.
- Aspects involving movement, jumping or balance — look to the take-off phase for primary errors, most discrepancies afterwards are secondary errors. Similarly most problems observed at the instant of landing or ‘arriving’ in a position to play a stroke find their roots in the initial take-off.
- Problems in the direction of movements — look to the direction of force applied for the primary error. If a stroke results in the ball going to the wrong place perhaps the contact was at the wrong timing and as a result the force was incorrectly applied.
- Problems in developing power — look to the preparation for the particular stroke, insufficient flexion and extension of the leg joints are primary errors. Often the sequence of joint rotations or flexions and extensions are not in the right order. With rotational power be aware of the principles of Angular Momentum and of the value of ‘whole body’ movement (use of free arm etc) both from the view of increased efficiency and preventing injury. The effective use of elastic energy is also important as are the use of the hips and stomach in influencing power.