Testing an Intervention to Improve Functional Capability in Advanced Cardiopulmonary Illness:

Physical activity patterns of patients with cardiopulmonary illnesses

OBJECTIVES

The aims of this paper were (1) to describe objectively confirmed physical activity patterns across 3 chronic cardiopulmonary conditions, and (2) to examine the relationship between selected physical activity dimensions with disease severity, self-reported physical and emotional functioning, and exercise performance.

DESIGN

Cross-sectional study.

SETTING

Participants' home environment.

PARTICIPANTS

Patients with cardiopulmonary illnesses: chronic obstructive pulmonary disease (COPD) (n=63), heart failure (n=60), and patients with implantable cardioverter defibrillator (n=60).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Seven ambulatory physical activity dimensions (total steps, percent time active, percent time ambulating at low, medium, and high intensity, maximum cadence for 30 continuous minutes, and peak performance) were measured with an accelerometer.

RESULTS

Subjects with COPD had the lowest amount of ambulatory physical activity compared with subjects with heart failure and cardiac dysrhythmias (all 7 activity dimensions, P<.05); total step counts were: 5319 versus 7464 versus 9570, respectively. Six-minute walk distance was correlated (r=.44-.65, P<.01) with all physical activity dimensions in the COPD sample, the strongest correlations being with total steps and peak performance. In subjects with cardiac impairment, maximal oxygen consumption had only small to moderate correlations with 5 of the physical activity dimensions (r=.22-.40, P<.05). In contrast, correlations between 6-minute walk test distance and physical activity were higher (r=.48-.61, P<.01) albeit in a smaller sample of only patients with heart failure. For all 3 samples, self-reported physical and mental health functioning, age, body mass index, airflow obstruction, and ejection fraction had either relatively small or nonsignificant correlations with physical activity.

CONCLUSIONS

All 7 dimensions of ambulatory physical activity discriminated between subjects with COPD, heart failure, and cardiac dysrhythmias. Depending on the research or clinical goal, use of 1 dimension, such as total steps, may be sufficient. Although physical activity had high correlations with performance on a 6-minute walk test relative to other variables, accelerometry-based physical activity monitoring provides unique, important information about real-world behavior in patients with cardiopulmonary illness not already captured with existing measures.