<unk>  is a symptom of a small handful of certain neuromuscular disorders characterized by delayed relaxation (prolonged contraction) of the skeletal muscles after voluntary contraction or electrical stimulation.<unk>  is the defining symptom of many channelopathies such as<unk>  congenita, paramyotonia congenita and<unk><unk> . Generally, repeated contraction of the muscle can alleviate the<unk>  and relax the muscles thus improving the condition, however, this is not the case in paramyotonia congenita. This phenomenon is known as the "warm-up" reflex and is not to be confused with warming up before exercise, though they may appear similar. Individuals with the disorder may have trouble releasing their grip on objects or may have difficulty rising from a sitting position and a stiff, awkward gait.<unk>  can affect all muscle groups; however, the pattern of affected muscles can vary depending on the specific disorder involved. People suffering from disorders involving<unk>  can have life-threatening reactions to certain anaesthetics called anaesthesia-induced rhabdomyolysis.
symptom of Myotonic dystrophy
symptom of Duchenne muscular dystrophy
symptom of Amyotrophic lateral sclerosis
symptom of Tay–Sachs disease
symptom of Lesch–Nyhan syndrome
symptom of Myasthenia gravis
symptom of Buschke–Ollendorff syndrome
symptom of Multiple sclerosis