Athletes should never take salt tablets because they:
Heat cramps are likely caused by losses of water and electrolytes [3] (salt and potassium) from excessive sweating. The priority for any athlete should be to replace that water and electrolytes, such as by drinking a sports drink. [4]
Links:
[1] https://mail.momsteam.com/node/273
[2] https://mail.momsteam.com/node/276
[3] https://mail.momsteam.com/node/865
[4] https://mail.momsteam.com/node/280
[5] https://mail.momsteam.com/nutrition/sports-hydration/heat-illnesses/warning-signs-and-symptoms-of-dehydration-kids-can-become-dehydrated-in-cold-weather
[6] https://mail.momsteam.com/health-safety/replace-electrolytes-lost-during-sports-with-sports-drinks
[7] https://mail.momsteam.com/health-safety/dehydration-signs-and-symptoms
[8] https://mail.momsteam.com/nutrition/sports-nutrition-basics/extra-salt-most-youth-athletes-dont-need