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People with chronic obstructive pulmonary disease (COPD) tend to have abnormally low levels of fat-free mass (FFM), which includes skeletal muscle mass as a central component. The purpose of this systematic review was to synthesise available evidence on the association between FFM and exercise test outcomes in COPD. MEDLINE, Cochrane Library, EMBASE, Web of Science, and Scopus were searched. Studies that evaluated exercise-related outcomes in relation to measures of FFM in COPD were included. Eighty-three studies, containing 18,770 (39% female) COPD participants, were included. Considerable heterogeneity was identified in the ways that FFM and exercise test outcomes were assessed; however, higher levels of FFM were generally associated with greater peak exercise capacity. This association was stronger for some exercise test outcomes (e.g. peak rate of oxygen consumption during incremental cycle exercise testing) than others (e.g. six-minute walking distance). This review identified heterogeneity in the methods used for measuring FFM and exercise capacity. There was, in general, a positive association between FFM and exercise capacity in COPD. There was also an identified lack of studies investigating associations between FFM and temporal physiological and perceptual responses to exercise. This review highlights the significance of FFM as a determinant of exercise capacity in COPD.

Purpose of Review: Exertional breathlessness is common and pervasive across various chronic disease populations. To accurately assess response to intervention and optimize clinical (symptom) management, detailed assessment of exertional breathlessness is imperative. This review provides an update on current approaches to assess exertional breathlessness and presents the need for individualized assessment of breathlessness standardized for the level of exertion., Recent Findings: Breathlessness assessment tools commonly invite people to recall their breathlessness while at rest with reference to activities of daily living. To directly quantify breathlessness, however, requires assessment of the dimensions of breathlessness (e.g., sensory intensity, quality, and unpleasantness) in response to a standardized exercise stimulus. Different exercise stimuli (e.g., self-paced, incremental, and constant work rate exercise tests) have been used to elicit a breathlessness response. Self-paced (e.g., 6-min walk test) and incremental exercise tests assess exercise tolerance or endurance, and are not recommended for assessment of exertional breathlessness. Constant work rate tests, however, including recently validated 3-min constant-rate stair stepping and walking tests, standardize the exercise stimulus to enable the breathlessness response to be directly quantified and monitored over time., Summary: To adequately guide symptom management and assess intervention efficacy, clinicians and researchers should assess breathlessness with multidimensional assessment tools in response to a standardized and individualized exercise stimulus.