Neuromuscular fatigue

You may notice that climbing stairs, lifting, chewing, speaking or holding your arms up becomes harder after repeated effort. Muscles can feel heavy, shaky or weak rather than simply sleepy. Heat, poor sleep, dehydration, infection, under-eating and prolonged stress can contribute. Anaemia, kidney disease, coeliac disease, medication effects and disorders affecting nerves or muscles are other possibilities. The pattern matters: weakness that varies through the day, follows exertion or affects breathing and swallowing needs careful evaluation. Fatigue after a viral illness, including COVID-19, may last beyond the initial infection.

Reduce demanding activity for now, pace tasks and take planned rest before you become exhausted. Drink regularly, eat balanced meals and keep a simple diary of triggers, affected muscles, duration and recovery. Avoid driving or working at heights if weakness is unpredictable. Arrange a medical review when symptoms persist, recur or limit ordinary activities. A clinician may examine strength, reflexes and sensation and decide whether blood tests or other investigations are needed.

Call emergency services for rapidly worsening weakness, trouble breathing, choking, new difficulty swallowing, inability to stand, new one-sided weakness or confusion. Seek prompt advice for dark urine after strenuous activity, fever with severe weakness, repeated falls or weakness that follows a new medicine. Do not wait for a routine appointment if weakness is progressing.

Ask whether the problem sounds like muscle fatigability, general fatigue or nerve weakness; which medicines, infections or nutritional issues could contribute; and whether you need strength testing, blood tests or referral. Bring your symptom diary and list of supplements.