Most sports within the Paralympic movement are not identical to their able-bodied equivalent, but instead adopt different sport and equipment rules to better account for the capabilities of people with impairment. For instance, in the regular unadapted form of judo played by those without impairment, athletes start the bout by fighting to obtain the most advantageous grip of their opponent, before continuing to compete with the grip in place. However, in the adapted form of judo played by those with VI, athletes start with the grip already in place, so that the athlete with better vision does not hold a substantial advantage in obtaining a grip on their opponent. A variety of sport adaptations of this type are used within VI sports, and those adaptations hold significant consequences for the way in which research into evidence-based classification should be conducted.
There are two important steps involved in classification for an athlete who wishes to take part in para-sport. In the first step, the athlete must have an eligible impairment that meets the minimum impairment criterion (MIC), defined as “the level of impairment that has an impact on sport performance” [
6,
7]. Crucially, the MIC for para-sports should be the level of impairment that decreases an athlete’s level of performance in the unadapted form of the sport. That is, if a judoka’s VI impacts their ability to compete when following the rules of the unadapted form of the sport (i.e., when required to obtain a grip on their opponent), then they should be eligible to take part in the para-version of the sport. The second step during classification requires an athlete to be allocated a sport class so he/she competes against others with a similar activity limitation. Because para-athletes will compete against each other in the adapted form of the sport, the sport class should be determined on the basis of the impact of the impairment on performance in the adapted form of the sport. If two judokas with VI have different levels of impairment that provide one with an advantage when obtaining a grip, yet no advantage when the grip is in place, then the two athletes should compete in the same sport class.
The decision to make adaptations to sport rules and equipment in VI sports is the responsibility of the individual sport federations responsible for governing those sports (for a list of those federations, see Tweedy et al. [
8]). Federations generally try to minimise these adaptations so that the sport remains as similar as possible to the sighted version; however, it should now be clear that, when made, these modifications hold significant implications for evidence-based classification. In turn, the outcomes of classification research can lead Federations to consider changes to their technical rules. Below we address two modifications commonly used in VI sport (blindfolds and guides) that have significant implications for how evidence-based classification should be established.
2.1 Blindfolds
Blindfolds (or eyeshades) are used in some VI sports to ensure that all athletes have an equivalent level of impairment during competition (i.e. full blindness). Some VI sports require all athletes to wear a blindfold (e.g. goalball), while other sports require only a subset of athletes to do so (e.g. those with the most severe impairment, as is presently the case for VI swimming).
It has been suggested on occasion that a suitable approach to minimise the impact of impairment on the outcome of competition in VI sport would be to require all athletes to wear a blindfold during competition irrespective of the severity of the athlete’s VI. However, there are several reasons why most people in VI sports do not accept this view [
9]. First, a blindfold will add to the existing VI of an athlete who is not completely blind, limiting their ability to capitalise on their remaining vision, a skill that is developed through training. Second, there is concern that when compared with those who are completely blind, those who have some degree of vision but compete with a blindfold might in certain cases perform better during competition because they benefit from having vision away from competition. Indeed, those with some vision may have an advantage not only in their ability to access training but also during training; for instance, when visually modelling their actions on others and when using visual feedback (e.g. video). Conversely, those who are completely blind could, in some cases, have an advantage if competing with a blindfold because they may be better adapted to living and competing when fully blind. Evidently, a consultation process with experts in VI sports revealed that rather than being required to use blindfolds, most VI athletes would prefer to compete without one, even if that meant that they might need to compete in a class against others who have less impairment than they do [
9].
Although the use of blindfolds in VI sports remains a controversial issue, there is general agreement that blindfolds are acceptable in some situations (for a discussion see Ravensbergen et al. [
9]). The decision to use blindfolds within a given sport is at the discretion of the individual sport federation governing that sport, although the decision does hold significant implications for how a system of classification should be developed. Given that the minimum impairment criteria should be established on the basis of performance in the unadapted form of a sport, then the criteria should be established by examining performance without the blindfold in place. However, the nature of the research to be performed to establish the sport classes will depend on whether either some or all athletes are required to wear a blindfold during competition.
If all athletes are required to wear a blindfold during competition, then it can be argued that only one class should be necessary because all athletes will have the same level of VI during competition. Further research is unlikely to be necessary because there is no need to establish the relationship between impairment and performance when all athletes have the same level of impairment. If research was to be conducted with the blindfolds in place, and did find better performance by those who have less impairment, then this would imply that differences away from competition (e.g. advantages during training), or perhaps the development of other skills (e.g. balance), have a direct impact on performance during competition. Typically, these factors should not be accounted for during classification.
If only a subset of athletes is required to use blindfolds during competition, then research for the allocation of sport classes should be performed on the basis of performance when those athletes required to wear a blindfold do have the blindfold in place. This can present a particular challenge for evidence-based classification because it will not be clear what an athlete’s level of performance might be like without the blindfold in place. When only some athletes must wear a blindfold, it is typically only those who compete in the class for athletes with the most severe VI who must do so. Conceptually, an athlete should be placed into this class when they (1) would be disadvantaged when competing, without the blindfold, against others with less impairment, and (2) would not have an advantage when competing, either with or without the blindfold, against others with more impairment. Consider, for example, VI swimming, where athletes with the most impairment, who currently compete in class ‘S11’, must swim with fully blackened goggles (unless they have two prosthetic eyes), while those with less impairment in classes ‘S13’ and ‘S12’ do not use blackened goggles. Within class S11, most athletes are blind, but there is also a subset of athletes who have a minimal level of vision. Those athletes typically only have the ability to perceive light, yet must compete blindfolded, presumably at least in part to remove any perceived advantage they might have over others who are fully blind. At present though it remains unclear whether those athletes who can perceive light would possess any advantage if allowed to compete without the blindfold. Research is required in that case to show whether the athletes who have minimal vision would perform better without the blackened goggles. Accordingly, an evidence-based decision can be made about whether those athletes should compete in a different class to those who are fully blind, either in a class against athletes with less impairment, or in a separate class altogether. If so, the sport federation should reconsider their requirement for those athletes to compete blindfolded.
2.2 Guides
People with VI frequently experience difficulties in their ability to move safely through their environment. A number of sports such as triathlon and skiing account for this impairment in orientation and mobility [
10] by allowing VI athletes to be accompanied by a guide, whose function is to safely lead the athlete during competition. Whereas blindfolds can generally limit or diminish an athlete’s ability to perform, guides help to optimise an athlete’s performance.
The choice to allow guides during competition is another rule-related issue that is at the discretion of a sport federation. If a guide is used in the adapted form of the sport, then the minimum impairment criteria should once again be established on the basis of performance without the guide when competing in the unadapted form of the sport, while the determination of sport classes should be done when considering performance with the guide. However, in some sports, the overall performance of an athlete will depend, at least in part, on the individual contribution of the guide, and therefore this ideally needs to be controlled when establishing the relationship between impairment and performance during classification research. For example, in VI para-cycling, athletes compete while riding a tandem bike with their guide, with both the athlete and their guide cycling the pedals. Therefore, the athlete’s overall performance will depend not only on their own contribution but also that of the guide. For the purposes of classification research, the contribution of the guide should be controlled or eliminated when establishing the impact of impairment on an athlete’s performance, for instance, by standardising the contribution of the guide (e.g. using the same guide for all athletes); limiting the contribution of the guide to one of orientation rather than also contributing to locomotion (unless required for safety); or testing the performance of the athlete without the guide present, using modified equipment (e.g. a stationary bicycle ergometer) while simulating competition.