This paper explores the measures available to assess and predict intensive care unit-acquired muscle weakness. The discussion centres around the selection of the appropriate muscle to test in order toÂ make adequate predictions of a patient’s outcome. The authors propose that the upper airway dilators are much more susceptible to a decrease in muscle strength than the diaphragm, and impairment of upper airway patency is a key mechanism of extubation failure in intensive care unit patients. Additionally data suggests that the adductor pollicis muscle is an appropriate reference muscle to predict weakness of muscles that are typically affected by intensive care unit-acquired weakness, i.e., upper airway as well as extremity muscles. Stimulated (evoked) force of skeletal muscles, such as the adductor pollicis, can be assessed repetitively, independent of brain function, even in heavily sedated patients during high acuity of their disease.