Athletes lose extra salt because they sweat profusely, more than a normal citizen. In such cases, they need a higher sodium intake than the usual recommendations.

Sometimes salt can be serviceable, not just delicious!

References

1. Valentine, V. 2007, ‘The Importance of Salt in the Athlete’s Diet’, Current Sports Medicine Reports, vol. 6, issue 4, pp. 237-240, https://journals.lww.com/acsm-csmr/fulltext/2007/08000/the_importance_of_salt_in_the_athlete_s_diet.9.aspx.