|  | Feature: “ICSEMIS Researchers Award” | No.56 May 2009 |
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Towards Evidence Based Classification – the Need for Tests of Activity Limitation and Preliminary Findings Emma M. Beckman & Sean M. Tweedy |
Competition is the factor that differentiates sport from physical activity and it is this competition that motivates people to participate in sport1. However, if competition is viewed by the participant as one-sided or unfair, motivation to participate is reduced. Classification is a means of reducing the likelihood of one sided competition and, in so doing, promoting participation in sport. For example, in the sports of boxing and weightlifting, classification of body mass separates competitors of largely different body size, reducing the extent to which body mass influences competition outcome and increasing the relative influence of strength, skill, training and strong psychological attributes. In the sport of athletics (track and field) classification of gender and age reduce the extent to which these factors impact on competition outcome. Athletes below the age of 18 and above the age of 35 are classified by age to minimize the impact that age has on the outcome of competition in junior and master sport. In most instances, men and women compete separately to minimise the impact that gender has on the outcome of competition. In this way, classification increases participation, providing a framework for competition that reduces the likelihood of one-sided competition. Classification in Paralympic Athletics serves the same purpose. It is a means of increasing participation by decreasing the impact that impairment has on the outcome of competition2. Currently however, methods of classification are based on expert opinion and given the importance and scope of the Paralympic games, this is not satisfactory. The International Paralympic Committee recognizes this fact and in 2007 ratified the Classification Code which, inter alia, mandates the development of evidenced based systems of classification for all Paralympic Sports. To be evidence based, a classification system needs a clearly stated purpose and evidence that the methods used to classify will achieve that purpose. Paralympic Athletics is the first of the Paralympic sports to address this need for an evidence based system. The IPC Athletics Classification Manual for Physical Impairments 2009-12 was ratified in 2009 and its stated purpose is to minimize the impact of impairment on the outcome of competition in the sport of athletics2. Conceptually, in order to minimize the impact of impairment on the outcome of competition, impairments must be measured and classified according to how much they impact upon athletic performance or, in the lexicon of the International Classification of Disability, Functioning and Health 3 impairments must be classified according to how much activity limitation they cause 2 4. This statement of purpose and conceptual basis for classification in Paralympic athletics was first proposed by Tweedy in 2002. A classification system that succeeds in minimizing the impact of impairment on the outcome of competition will ensure that athletes who succeed in Paralympic events do so because they have “the most favorable anthropometric, physiological, and psychological attributes and have enhanced them to best effect by legitimate means such as training, diet, event technique, and legal technical aids (e.g., strapping and/or prosthetics, equipment design), not because their impairment is less severe than their competitors” 2. To achieve this aim requires research to develop evidenced-based methods for classifying impairments of coordination, range of movement and strength according to how much activity limitation they cause in each of the four fundamental activities of Paralympic athletics – running, jumping, throwing and wheelchair propulsion. To quantify how much a given neuromusculoskeletal impairment impacts upon any of the activities will require the development of valid, standardised tests of impairment that reflect eligible impairment types, specific to the activity of interest. In conjunction to tests of impairment, the development of batteries of activity limitation tests are required. Activity limitation test batteries will be of use to classifiers in the cross validation of impairment profiles of athletes and will also provide an indication of performance and training level of an athlete. Activity limitation test batteries that provide an indication of training level are needed because the primary basis for assigning athletes to classes will be impairment severity, which will be assessed using standardised tests of impairment. However, although impairment assessments are largely training resistant, they are not entirely. This means that athletes could, through training, decrease their impairment score and be placed in a more functional class. For the integrity of the sport it is vital that this does not occur to ensure that athletes who have positively influenced their impairment scores through training are not disadvantaged in this way. Tests that will permit classifiers to differentiate athletes who are highly trained from those who are not are therefore required. A battery of tests of activity limitation should include the activity of interest (wheelchair racing, running, throwing or jumping) and should also include supplementary tests of activity limitation which can provide a more complete indication of the interaction between an athlete’s impairment type / severity and the level of training. Valid supplementary tests should meet the following criteria: a) be predictive of running performance; b); be kinematically distinct from running c) collectively reflect the impact of the range of eligible impairment types (viz. impaired coordination, impaired muscle power and impaired active range of movement) and d) be cheap and easy to administer, in order to facilitate international dissemination and implementation. At the ICSEMIS convention in Guangzhou, a study was presented which evaluated the validity of a battery of activity limitation tests for running. Tests were developed by an expert panel and were selected if they met the criteria for tests of activity limitation and emphasised the eligible impairment types of strength, range of motion and coordination, Where possible, tests were drawn from previous literature that identified tests with a strong relationship to running performance and where this information was not available, novel tests were developed. Five supplementary activity limitation tests and a criterion activity test of top speed running were selected. The five supplementary activity limitation tests were; the standing broad jump (SBJ), 4 bounds for distance (4B), 10m speed skip (10skip), running in place (RIP) and split jumps (SJ). The standing broad jump and 4 bounds were identified in the literature as tests that have previously been shown to relate to sprint performance and are primarily determined by power. RIP and SJs were developed from coaching and training literature due to a lack of literature investigating tests that were primarily determined by coordination. The 10m speed skip was included as a test that is primarily determined by power and range of motion but also by coordination. The aims of this study were to: evaluate reliability of the tests and provide an indication of normative performance for each test; evaluate the strength of association between each of the supplementary tests and running performance and evaluate the predictive validity of the supplementary test battery. It is recognised that prior to being used for Paralympic classification purposes, an activity limitation test battery must be evaluated in athletes with disabilities. However this study, which evaluated the battery in a non-disabled population, is an essential forerunner of such studies for two reasons. Firstly, the psychometric properties of the tests must be evaluated without the confounding influence of impairment and secondly, meaningful interpretation of studies involving athletes with disabilities will be dependent on a sound estimate of normative performance for each of the six activity limitation tests. Results from the non-disabled sample showed good reliability and normal performance ranges for each test were reported. Results indicated that some of tests, particularly those emphasising strength and power were well correlated to running performance but that two of the tests that emphasised coordination showed much lower predictive validity. It was hypothesised that this was a product of a threshold effect; that all participants in our non-disabled sample had a threshold level of coordination which was sufficient to run quickly but that participants with impairments of coordination (ataxia, athetosis and increased muscle tone) may not reach this threshold and therefore a stronger relationship to these particular tests that emphasise coordination might be evident. In conclusion, this study evaluates the psychometric properties of an activity limitation test battery in non-disabled participants. The findings indicate that the test battery is reliable and that, without the confounding influence of impairment, the supplementary tests provide a strong and valid estimate of activity limitation in running. The findings also establish normative performance ranges for each of the tests, a necessary pre-requisite for meaningful interpretation of future studies in athletes with impairments. These findings indicate that the battery has potential utility in Paralympic classification and further studies evaluating the test battery in populations of athletes with impairments of coordination, strength and range of movement are now both warranted and possible References 1. Gill D. Competitiveness and competitive orientation in sport. In: Singer R, Murphy, M, Tennant, LK, editor. The Handbook of Research on Sport Psychology. New York: McMillan Publishing Company, 1993. 2. Tweedy S, Bourke, J. System specifications and overview of the classification process. In: International Paralympic Committee, editor. IPC Athletics Classification Manual for Physical Impairments 2008-2010. Bonn: International Paralympic Committee, 2007:8-14. 3. World Health Organisation. International Classification of Functioning, Disability and Health (ICF). Geneva: World Health Organisation, 2001. 4. Tweedy S. Taxonomic theory and the ICF: foundations for a unified disability athletics classification. Adapted Physical Activity Quarterly 2002;19:220-237. Contact Emma M. Beckman, Ph.D University of Queensland Brisbane, Australia Email: e.beckman@uq.edu.au icsspe.org/index.php?m=15 Towards Evidence Based Classification – the Need for Tests of Activity Limitation and Preliminary Findings Emma M. Beckman & Sean M. Tweedy