Examples of challenging in a sentence. 1  I find the job challenging and fun. 2  Teaching is challenging but rewarding work. 3  It's a challenging book that requires careful reading.  The slope was challenging for even the most experienced climbers.
Electromyography (EMG) is an electrical recording of muscle activity that aids in the diagnosis of neuromuscular disease. Muscles are stimulated by signals from nerve cells called motor neurons. This stimulation causes electrical activity in the muscle, which in turn causes contraction. This electrical activity is detected by a needle electrode inserted into the muscle and connected to a recording device. Together, the electrode and recorder are called an electromyography machine.
ECG (EKG) (electrocardiogram): A record of the electrical impulses that immediately precede contraction of the heart muscle. The waves produced are known as the P,Q,R,S and T waves. An ECG is a useful means of diagnosing disorders of the heart, many of which produce deviations from normal electrical patterns. Electrocardiography causes no discomfort. Electrodes connected to a recording machine are applied to the chest, wrists, and ankles. The machine displays the electrical activity in the heart as a trace on a moving graph or on a screen. An ECG can be taken at home; a 24-hour record can be obtained from a tape recorder worn by the patient.