Exercise testing

When assessing a patient, testing exercise capacity will: • Determine the level of impairment in disability • Enable a safe and effective exercise programme to be prescribed • Test the effects of therapy such as pulmonary rehabilitation on exercise capacity • Assess the extent of lung disease, by stressing the system • Assist in the diagnosis of unexplained breathlessness on exertion. ✔ Six minute walk test (6MWT) For this test: • The patient is encouraged to walk as far as possible at his or her own pace for 6 min • Standardized encouragement is given, but there is a learning effect and two or three practice runs need to be done • The total distance walked is measured • The patient is fitted with a pulse oximeter and oxygen saturations are measured throughout • The distance covered correlates well with lung function and diffusing capacity but not with oxygen saturations during the walk • A typical COPD patient with an FEV1 of about 1 litre or 40% of predicted, would walk about 400 metres • There is a lot of intersubject variability, which depends on motivation, emotional state, and expectations. ✔ Shuttle walk test (SWT) For this test: • The patient walks around two markers, 10 metres apart • The pace of walking is set by an audio signal which increases in frequency • The patient continues the shuttle until they cannot keep up, and the distance walked is expressed in metres • The SWT is a reproducible test of maximal capacity; the 6MWT is less reproducible, but is closer to real life activity