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Proportions of activities in a climbing gym
  1. David Humphries
  1. Sports Medicine, St Helens Hospital 186 Macquarie St, Hobart Tasmania, Australia drdavid{at}ozemail.com.au
    1. Deborah Wright,
    2. James Royle,
    3. Tim Marshall

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      Editor,—I refer to the paper on indoor rock climbing by Wright et al.1 Firstly, thanks to the authors for adding some valuable information to the under researched area of indoor climbing injuries (particularly given the popularity of this activity world wide).

      While I have no doubt that many of your participants put leading or bouldering as the activity that they spent most time doing while in the gym, I would have significant doubts that that is actually the case, particularly in lower grade climbers. I suspect that the participants in the study may well have overestimated the amount of time they spent in each activity, and that an analysis of actual time spent would reveal more time spent on a top rope than any other activity. This is a possible explanation for the otherwise unexpected findings when looking at the “preferred activity” as a predictor of overuse injury.

      I do agree with the idea that many “committed” climbers will spend more time bouldering and leading than the non-committed, but this should logically be a factor to some extent related to grades climbed, not independent of skill level.

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      Authors' reply

      Thanks to David Humphries for his comments on our paper. We agree that our respondents may have overestimated the time they spent leading and bouldering in comparison with top roping, although, if this is the case, we should ask why. Bravado, perhaps wishing to appear bolder than they actually are, or memory error, seem the most likely explanations. Memory error, resulting in this case in misclassification bias, is a potent source of error in epidemiological studies, a bias to which our study is no less susceptible than others reliant on memory based replies. If the misclassification is all in one direction—that is, some people stated that their most common activity was leading and bouldering when it was in fact top roping, and no one made the opposite error—the true odds ratio for leading and bouldering in comparison with top roping would be lower than that which we found. We have not performed a sensitivity analysis to estimate the degree of misclassification that would reduce the coefficient of this variable to non-significance.

      We have one further comment to make in relation to Humphries' remarks about “committed” climbers. We have already pointed out that we cannot regard our sample as a true cross sectional representation of the indoor climbing population. In particular, it seems unlikely that “team building” clients from the commercial sector would attend such an event, and possibly not school groups, or at least not in the proportions that they are believed to represent of a rapidly expanding market. In this sense, we suspect that almost all our respondents would be “committed” climbers, but the word has a different sense here from the way Humphries has used it.

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