Muscle cramps

A cramp is a sudden, painful locking of a muscle, often the calf or thigh, late in a long or fast effort. It is mainly a sign of muscle fatigue, not just dehydration.

• On the spot: slow down or stop, gently stretch the muscle 20 to 30 seconds (for the calf, pull your toes towards you), massage it, then walk a little.
• Common causes: going faster or longer than you have trained for, heat, a history of cramps.
• What usually helps: realistic pacing, building long runs and race pace gradually, drinking to thirst.
• See a doctor if cramps come often at rest or at night, a calf stays painful and swollen, or a muscle aches for days with dark urine. Confusion or vomiting in the heat needs urgent help.