This investigation was conducted to study whether warming up decreases myotonia (muscle stiffness) during speech production or causes adverse effects due to fatigue or exhaustion caused by intensive speech activity in patients with adult onset myotonic dystrophy. Thirty patients with adult onset myotonic dystrophy (MD) and ten healthy controls were examined, using a protocol that requires subjects, to speak continuously for at least 10min. In MD patients, warming up led to an increase in speech rate and a decrease in speech variability without causing signs of fatigue or exhaustion as a result of prolonged and intensive use of the speech musculature. No significant changes were found in the controls. After warming up, MD patients achieved a habitual speech rate in reading and reciting similar to that of healthy controls. Learning outcomes: As a result of this activity the reader will learn that: (1) In contrast to most neuromuscular disorders, speech production in patients with adult onset myotonic dystrophy improves by activity; (2) Myotonia in speech musculature in patients with adult onset myotonic dystrophy can be reduced by instructing them to warm up their muscles by repetitive movements; (3) Warming up is a valuable intervention because it improves the velocity and fluency of speech production without aggravating the signs of flaccid dysarthria.