Sodium Loading

Sodium loading is a pre-race hydration strategy where athletes deliberately increase their sodium intake for 24–48 hours before a hot-weather endurance event. The goal is to expand blood plasma volume — the liquid portion of your blood — which improves cardiovascular efficiency, thermoregulation, and sweat output in the heat. Think of it as "pre-loading" your body's cooling system.

The science is straightforward: sodium helps your body retain water. When you consume extra sodium with adequate fluids, your kidneys retain more water in the bloodstream rather than excreting it as urine. This expanded plasma volume means your heart can pump more blood per beat (higher stroke volume), deliver more oxygen to muscles AND more blood to the skin for cooling — simultaneously. In hot conditions, this dual benefit is significant.

Protocols vary, but a common approach is consuming 1,500–3,000 mg of extra sodium per day for 2 days before a hot race, along with normal-to-slightly-increased fluid intake. Practical methods: adding salt to meals, drinking electrolyte solutions (like The Right Stuff or SaltStick caps with water), or sipping broth. The morning of the race, many athletes take a concentrated sodium bolus (e.g., 500–1,000 mg with 16 oz water) 60–90 minutes before the start.

Practice sodium loading before a hot training session first — don't debut it before your A-race

Salty foods work: pretzels, pickles, miso soup, salted pasta the night before

If using salt capsules, take them with 8–12 oz of water each to avoid GI distress

Athletes with high blood pressure or kidney conditions should consult a doctor before sodium loading