Samenvatting

To date, limited research has been conducted on hydration in surfers and no
recommendations could be found regarding optimal hydration practices in surfers. This
makes it difficult for dietitians and surf coaches to give evidence-based advice to surfers
regarding optimal hydration practices. In order give recommendations to surfers concerning
optimal hydration, research is needed to investigate the degree of dehydration at which
surfing performance and the possible factors influencing surfing performance are impaired.
Further, the current hydration behaviour of surfers needs to be investigated by means of
objective measurements. Aim: To gain insight into hydration in surfers and the possible
implications on surfing performance. Method: The hydration status before surfing was
measured by means of urine specific gravity (Usg), the sweat rates were investigated by
means of body mass difference after compared to before surfing and hydration behaviour
was assessed using a questionnaire asking for the usual drinking behaviour of the
participants before and after surfing and the perceived importance of hydration for
performance. The interrelationships between hydration behaviour and sweat rate and
hydration behaviour and hydration status before surfing were determined by means of
Spearman correlations and student t-tests using SPSS 20. Moreover, a literature study was
conducted to assess the influence of dehydration on surfing performance and the actual
amount of fluid intake in surfers. Results: Twenty-two male surfers were included in the
analysis. As indicated by a Usg greater than 1.020 g/ml, 45% of the participants were
dehydrated prior to surfing. The average Usg of all samples was 1.019 g/ml. The mean sweat
rate was -0.48 litres per hour resulting in a mean body mass loss of -0.6% per hour. When
asked about their hydration behaviour prior to surfing 37% of the participants indicated that
they drink extra fluids only “sometimes” or “never” before surfing. Eighteen per cent of the
surfers indicated that they “always” ingest extra fluid before surfing and 45% “mostly” ingest
extra fluid. In contrast, 77% indicated that they “always” or “mostly” drank additional fluids
after surfing and 23% “sometimes” consumed extra fluid. No relationship could be found
between reported drinking behaviour and Usg or sweat rate (P>0.05). Participants rated the
importance of hydration with a mean score of 8.1 out of 10. No significant correlation was
found between Usg and hydration-importance-rating (P>0.05). Conclusion: There is a clear
discrepancy between the knowledge about the importance of hydration and the reported
drinking behaviour and measured hydration status. Sweat losses during surfing in
combination with hypohydration before the start of the surfing session or a longer duration of
the surfing session can lead to a significant level of dehydration to impair surfing
performance. The results show that hydration guidance in surfers should be individualized
and based on the individual sweat rate of the surfer while the importance of hydration before
surfing should be stressed.