Validation of HeadCount-2w for estimation of two-week heading: Comparison to daily reporting in adult amateur player.

<p><b>OBJECTIVES: </b>To validate the HeadCount-2w questionnaire for estimation of 2-week soccer heading by comparison to daily electronic diary reporting over the same two-week period.</p><p><b>DESIGN: </b>Prospective observational study.</p><p><b>METHODS: </b>Adult amateur soccer players completed HeadCount-daily, comprising 14 daily at-home assessments of soccer play and heading via a tablet PC. Following the 14day period, players completed HeadCount-2w, a web-based two-week-recall questionnaire on soccer and heading. intraclass correlation coefficient (ICC) was estimated between HeadCount-daily, the reference standard, and HeadCount-2w estimates of heading during the same 2-week period.</p><p><b>RESULTS: </b>53 participants (38 men) reported a mean of 24.36 (median=11.76) headers during 2 weeks via HeadCount-daily and a mean of 38.34 (median=15.0) headers for the same 2 weeks via HeadCount-2w. The ICC comparing 2-week heading from HeadCount-daily and HeadCount-2w was 0.85. Linear regression of the log-transformed Headcount-daily on HeadCount-2w data yielded a slope of 0.71 (p<0.001; 95% CI 0.54-0.82), suggesting that heading tends to be over-estimated by HeadCount-2w relative to HeadCount-daily. Slope estimates for men (0.65) and women (0.71) were similar.</p><p><b>CONCLUSIONS: </b>HeadCount, a self-administered web-based survey, is valid for self-reporting 2-week heading in adult amateur players, supporting its use in future research and as a simple and low-cost technique for exposure monitoring.</p>