Measures of Fluid Loss during Surfing: A Preliminary Analysis in Recreational Surfers

Surfing is a popular sport, but little is known about the extent to which recreational surfers experience fluid loss from this activity. The principal objective of this research was to estimate fluid loss during a surfing session through changes in pre- to post-session urine color (Ucol), urine osmolality (Uosm), and body mass (BM). Data were collected from 11 recreational surfers across 14 surf sessions conducted under various environmental (mean water temperature = 22.1 SD ± 2.3; range = 20-26oC; air temperature range = 13.1-31.5oC; relative humidity range = 37.5-88.1%) and surfing conditions (e.g. winter/summer, wave type, location, environmental and water conditions). Linear mixed effects models indicated that participants experienced significant pre- to post-session changes in BM (p < 0.001), but not in Ucol or Uosm. These findings suggested that recreational surfers may experience fluid loss (measured by pre- to post-surfing BM) that may impact on their performance and health, and therefore they should adopt a hydration strategy to minimize this impact.