Overhead throw is an important fundamental movement in many sports. It is categorized to be one of the early fundamental manipulative motor skills for every child to develop (Kathleen, 2004). This skill can be transferred to many other sports such as tennis serve, javelin throw and baseball pitching. The throw can be assessed either for accuracy (e.g. baseball pitching) or for distance (e.g. javelin throw) and there are some critical features that need to be present in the throw in order to achieve an optimum throw. In this study the goal is to achieve maximum distance and hence it is important to consider the law governing projectile motion which is angle of release, height of release and velocity of release. In qualitative studies, we use critical features or elements to cue the presence of these 3 features. The presence of upward ball path, the fully extended elbow in the throwing hand and the accelerated overhead arm swing are some of the actions to cue presence.
Critical features or elements are based on biomechanical factors that create the throw movement and are usually derived from quantitative analysis studies of throwers. One such factor is kinetic open chained movement where body segments or joints move in a combination. The movement involves chaining segmental movements such that the last segment is free to move E.g. in a kicking ball action, the hip flexes with the knee extends and dorsi-flexes during the kicking action and the relax arm action during an overhead throw. Another biomechanical factor is the concept of kinetic-link and stretch shorten cycle where there is an interaction of a linked system of body segments. (Kreighbaum and Barthels, 1985; Steindler, 1955). Each segment need to move in a sequential coordinated manner with precise timings of acceleration of proximal segment so as to transfer energy to distal segment.
In qualitative studies, physical education teacher and coaches observe these critical features for quick assessment on the overhead throw or other activity. Qualitative analysis is much preferred than quantitative analysis as it is not feasible and practical for physical education teachers and coaches to adopt quantitative analysis. There are many issues concerning using quantitative analysis such as time, cost, practicality and even ethical. Some parent may not be comfortable with their child being taken into lab for collection of data. One major advantage of qualitative analysis is that it allows skill to be assessed as a whole as the proficiency of some movement may be involving the interaction of every critical feature. In motor development milestone studies, qualitative studies take the approach of observing the critical features and analyze it with the motor skills developmental milestones. Getchell, 2005, motor development experts formulate logical decision tree checklist to assess the maturity of the critical features. Another method is to compare the performer with and expert, this allows the skill gap to be more visible. Intervention can later been drafted effectively to improve performance by emulating the technique of the expert.
The objective of this study is to show the use of qualitative analysis in improving a child (subject age 6) overarm throw. The throw will be maximal effort, thrown for distance. The comparison model will be of an adult expert thrower (subject age 30). Intervention will be suggested based on the qualitative analysis to improve throwing technique.
This study adopted Knudson & Morrison’s four-task integrated qualitative analysis model of preparation, observation, evaluation/diagnosis and intervention. Prior to the activity, an observational check list (Fig 2) was drafted using Gangstead and Beveridge, 1984, D. Knudson & C. Morrison, 1996 and Haywood & Getchell, 2005 model of an overhead throw. In this check sheet, the overarm throw was broken up into 3 phases which are preparation, action and follow through phases. Critical features for each phase were listed to assist in the observation and evaluation of the throw. An adult expert thrower was used for comparing the child’s throw. Each component and phases were evaluated objectively with a score of poor, average and good.
The adult and the child performer was tasked to do overarm throws (n=3) with maximal effort and distance of each throw was recorded using a standard 50m measuring tape. Maximal effort throw was chosen as the type of activity rather than throw for accuracy as the latter may be a difficult skilled task for the child. These eliminate the concern for motor developmental stage of the child. Children sponge tennis balls were used as projectile. Due to the experience level and language limitation of the child, he was given verbal instructions and a demonstration of the activity. The adult and child thrower performed the throws at two different locations due to child’s parents’ consents. Video of each throw was recorded using a Sony digital camcorder model: Model: DSR-PDS10P using a 2-dimensional analysis camera setup. The video data was analyzed qualitatively using the checksheet and the software use is a standard computer integrated media player, window media player.
Fig 1: Sequential phases of expert and child throw
Child achieved an average of 8.58m as compared to the expert thrower with 20.5m (Fig 3). From Fig 1 & 2, sequential phases and observational checklist, the child showed a different movement pattern from the expert and score poorly in terms of path of hub, bodyweight transfer and movement of the legs and trunk during the preparation, action and follows through phase. There is an absence of trunk utilization throughout the 3 phases. During the preparation and action phases, the child exhibited a poor homolateral lower body action where he bent his knee of the same side as the throwing hand. In addition, there were no bodyweight transfer and leg drive by the child in the preparatory and action phases.
On the other hand, the child showed similar upper body movement pattern in the action and follow through phase. There was an arm and humerus lag during the action phase. There was acceleration of his throwing arm in forward direction. The ball was released in an incline with his arm fully extended at the top of his head. The whole movement was accelerated, smooth and continuous. During the follow through phase, his arms swung across the body and relax. The child scored well in critical features of arm actions and the release of ball. As a whole, he show competency in the action phases with an average score and scored well in the follow through phase with a good score.
Fig 3: Throw Distances
Fig 2: Observational Checklist
The child has good upper body technique and if the child is able to throw consistently with this technique. Improvements could be made in leg drive, contral lateral leg action, sequential coordination, and angle of release. Practice should consist of a combination of games approach (GCA) and drills bearing in mind his age and motivational level. The whole throwing sequence can be broken down into parts to simplify learning. One example practice to improve leg drive and contral lateral leg action is by putting visual cues like colour spots or numbering spot for them to step on. Next, improvement of the angle of release can be taught by putting target on the wall and the child needs to throw toward the target. Different target height can be put so as to allow the child to explore and experience different angle of release. The presence of targets allows the child to direct his attention to the effects to the ball trajectory (external focus of attention) rather than directing their attention to their arm throwing form (internal focus of attention) hence making learning more effective (Wulf & Prinz, 2001). Sequential coordination should be the last to be taught as for many high-speed movements, it is the last refinement area for optimal performance. It said that development of sequential action will be limited until energy from the lower extremity can be channeled up to the body (Morrison & Knudson, 2002).
Before introducing the intervention, there should be some consideration in terms of his age and developmental milestones. There is a need to individualize the teaching and feedback hence his training should not be mixed with other children unless being group with similar profile. This is because children of the same chronological age may differ in developmental level and physiological age (Getchell, 2005). Models of good throw as a whole or segments need to be shown with good critical cues used during practice, research show that this can improves performance and learning best in children (Fronske, 1995; Masser, 1993; Weiss, 1982). Appropriate augmented feedback need to be given by identifying both strength and weakness with strength to be praised before reinforcement. According to Throndike’s law, 1927, people tend to repeat responses that are rewarded and avoid responses that are punished.
Evaluation, diagnosis and re-observation need to be done regularly to monitor progression. In addition, record keeping of the whole movement and critical features progression through observation check sheet provide reference to coaches and teacher on the progression of learning. Video recordings or pictures can be also be adopted to provide visual feedback to the child. This allows reflective learning which further enhances learning.
From this study, we can clearly see the practicality and the feasibility of qualitative studies in an activity. It is a low cost and quick way of skill and technique improvement process. As teachers and coaches, the use of video and checksheet can help to record and observe large number of students at the same time. The video data can then be viewed at a convenient time. With the current technology, the video can be played in slow motion where critical features can be objectively assessed. In the event of shortage of manpower, the use of observational checksheet allows the coaches and teachers to share the evaluation workload with other teachers or senior students without compromising the objectivity and validity of the evaluation. In addition, the videos and observational checksheet allow record keeping of subject performance for future development and studies. Exemplary skills can be shared and showed to future students and trainee for modeling purposes.
The possible challenge to the use of qualitative analysis is the perception its effectiveness. Teacher and coaches may perceive qualitative assessment may not be very objective as it is not absolute. When it comes to grading or selection exercise, the subject of fairness is questionable. There will be some resistance to the use of video analysis as some may find it difficult to use. To tackle these two issues, qualitative analysis can be made more objective and assessment friendly by having more details description in the observational checklist. As for the difficulty in using video, more training can be given to teacher and coaches. They can also be attached a mentor to assist. The proficiency will eventually be improved with more practice.