Water planning is an important risk management concern for road race event organizers.
Purpose: To compare water and cup prediction outputs from a mobile application (app) planning tool against: 1) measured group sweat losses, 2) documented event water and cup usage, and 3) traditional mathematical planning solutions.
Methods: Group mean sweating rates (L·h) from 12 published outdoor running studies were each compared to 12 composite averages using the Road Race Water Planner© (RRWP) app. Estimated water (gallons) and cup (number) needs were also compared with documented usage at a large marathon event and to traditional mathematical solutions.
Results: Thirteen group mean sweating rates from 286 runners were compared to composite RRWP estimates. Predicted sweating rate accuracy was 92% for RRWP and ranged from 0% to 69% for traditional mathematical solutions. The 2017 Boston marathon included 27,222 runners on a day averaging 21.5°C. Water and cup usage was 31,740 gallons and 1,036,003 cups, respectively. The RRWP estimates were 33,505 gallons and 1,072,160 cups, respectively. The difference in gallons expressed as liters was 0.236 L per person. For an approximately 4-h marathon, the difference per person as a rate was <60 mL·h. The difference in cups was a 3.5% error. All traditional solutions gave inferior estimates to RRWP due to large errors related to fluctuations in weather, as well as complications related to water station numbers.
Conclusions: The results of the RRWP analysis indicate that it can provide event organizers with a valid, quantitative way to narrow the uncertainties of water planning related to changes in participant numbers, race distance, and weather. "Rule of thumb" alternatives are also discussed.