Muscle function and electromyography: (almost) 70 years since Doty and Bosma (1956)

Swallowing, and dysphagia, the pathophysiology of swallowing, differ from most motor activities in that they are not readily observable without invasive imaging or measurement. Successful swallowing depends more on the precision of control and coordination with respiration than it does on force or work generation, which differs from many other motor tasks. Electromyography (EMG), an essential method for investigating motor function in general, has become critical to understanding the physiology of swallowing. In 1956, Doty and Bosma published a landmark paper using EMG to describe the motor pattern of a swallow. Since then, the specific methods of bi-polar indwelling electrodes have not significantly changed, but our understanding of muscle and ability to analyze EMG data has grown remarkably. Advances in imaging and quantitative analysis, largely derived from studies of fine motor control of the limbs and locomotion, are a boon to studies of swallowing and have advanced our understanding of neural control. EMG patterns are a direct readout of central motor control and are valuable for determining the evolution of swallowing, the normal physiology of swallowing, and the pathophysiology of dysphagia. The potential for increasing our knowledge of these aspects of swallowing is high, given current advances in EMG technique and analysis. Here, we briefly discuss the current state of our knowledge of the motor control of the swallow, review what we have learned in the past 70 years about the swallow, and end by highlighting how embracing novel technologies and techniques will enable us to further understand the neural control of this critical behavior.