How to Adjust Marathon Training for Hot and Humid US Summers

Training in hot, humid weather is a different sport. The goals: slow down, stay safe, and protect consistency. Here’s how to adjust without losing your race build.

Set realistic pacing in heat

• Expect pace to slow 10–30 seconds per mile (or more) as temps/humidity rise; use effort/HR, not goal pace.
• Use RPE 6–7/10 for easy runs; threshold by feel or HR zones if you have them.
• For long runs, start slower than cool-weather goal pace and finish steady, not fast.

Shift the schedule

• Run early or late when WBGT/heat index is lower; avoid mid-day sun.
• Split long sessions: e.g., 10–12 mi AM, 4–6 mi PM instead of one long scorch.
• Move hard workouts to cooler days; place strides on easy days when it’s hot.

Hydration and sodium

• Pre-hydrate 90–120 minutes before with water plus 400–800 mg sodium if you’re a salty sweater.
• During: 12–24 oz/hour depending on sweat rate; aim 300–600 mg sodium/hour.
• Post: 16–24 oz with sodium and carbs/protein; replace 100–150% of fluid loss.

Fueling in heat

• Carb targets stay similar (30–60 g/hr for most long runs), but stomach tolerance drops—test smaller, more frequent sips/gels.
• Keep gels/chews cool if possible; avoid overly concentrated mixes in extreme humidity.

Cooling strategies

• Pre-cool: cold drink/slurry, cool shower, ice bandana before hard/long runs.
• During: ice in hat/sports bra/neck; water over head if humidity is high.
• Clothing: light, technical fabrics; avoid cotton; ventilated hat/visor and sunglasses.

Modify workouts

• Swap intervals for tempo blocks when heat is severe to lower peak stress.
• Shorten rep duration and increase recovery (e.g., 4–5 x 5 min tempo with 2–3 min easy).
• Cap long runs by time, not distance, when heat index is high.

Safety checks

• Stop if chills, dizziness, nausea, or goosebumps in heat—cool down immediately.
• If you can’t keep HR/effort under control, jog/walk it in and live to train tomorrow.

Race-day adaptation

• Adjust race plan to forecast; pace the first 10K conservatively.
• Use every aid station for fluid and cooling; sodium if you’re a salty sweater.
• Prioritize finishing strong over early splits—heat PRs are earned late.

Using The Next Race

• Build heat-adjusted pacing notes into workouts (effort/HR caps).
• Log sweat rate and sodium strategy in workout notes.
• If paired with devices, review HR/pace drift to see when heat forces slowdown and adjust future sessions.