Watch for Signs and Symptoms of Heat Strain
Dizziness or lightheadedness (first noticed when standing up), nausea, irritability, headache, blurred vision or loss of peripheral vision, ringing in ears, clumsiness, misplacement of tools, shaky hands, vague flu-like symptoms, and fatigue.
If you see these signs in yourself, a friend or other hiker:
- Cool off with water
- Rest in the shade
- Drink fluids
- Eat food
- Check resting recovery pulse rate to assess the level of cardiovascular strain.
- Continue walking only when all symptoms are gone AND resting pulse is below 90 bpm.
Monitor for These Signs of Heat Strain
- A resting recovery heart rate of greater than 110 bpm. Sit down in the shade, wait 30 seconds, then take a pulse for one minute. Do this check every 1/2 – 1 hour.
- A sustained working heart rate that is >180 bpm–age = [ ].
- An axillary or oral temperature greater than 99.4 F.
- A daily weight loss > 1.5% indicates significant dehydration.
- A sitting to standing pulse increase of >20 bpm and other signs or symptoms of heat strain indicates significant dehydration. Wait 2 minutes after standing up before measuring for this change.