Increasing physical activity could aid severe asthma management
medwireNews: Researchers recommend addressing inactivity and sedentary time as a possible nonpharmacologic approach to managing severe asthma.
The recommendation is based on their findings that patients with severe asthma are “considerably” less active than the general population and that increasing activity levels and reducing sedentary time is associated with improved exercise capacity and asthma control, and lower levels of systemic inflammation.
The 61 patients with long-standing severe asthma (median of 27 years) achieved an average of 2455 fewer steps per day and 19.8 fewer minutes of moderate- to vigorous-intensity physical activity (MVPA) per day (p=0.0002, p<0.0001) than the 61 patients without asthma matched for age and sex.
Vanessa McDonald (National Health and Medical Research Council Centre of Excellence in Severe Asthma, Newcastle, New South Wales, Australia) and colleagues note that the patients with asthma achieved only 5362 daily steps, which is a little over half the recommended amount for adults.
Conversely, however, the patients with severe asthma did engage in an average 21.7 more minutes of light physical activity per day than controls (p=0.029). And there was no significant difference between the two groups in the time spent being sedentary.
The researchers report in The Journal of Allergy and Clinical Immunology: In Practice that steps, MVPA, and sedentary time were significantly associated with exercise capacity, as measured by the 6-minute walk distance (6MWD) test, explaining 35% (p=0.000), 30% (p=0.002), and 27% (p=0.006) of variance between individuals with and without asthma, respectively.
The relationship between daily steps and 6MWD was linear, with every additional 1000 steps walked per day increasing 6MWD by 16.9 m. For MVPA, there was a threshold effect, where individuals with severe asthma and a median 6MWD of 499 m or more were six times more likely to engage in recommended daily activity levels of at least 30 minutes.
McDonald and colleagues suggest that “this distance may be a suitable cutoff for people with severe asthma.”
For every minute increase in sedentary time, 6MWD decreased by 0.47 m, equating to a 28.2 m reduction for every hour spent sedentary.
“Sedentary time attenuated the associations of MVPA with exercise capacity but not the associations of [s]teps with exercise capacity,” the team notes.
Indeed, even after adjusting for sedentary time, an increase of 1000 steps each day was associated with a 22 m increase in 6MWD.
“This suggests that the greatest benefit on exercise capacity is achieved by performing activity of light to moderate intensity distributed throughout the day, rather than more vigorous but sporadic activity,” say McDonald et al.
Daily steps were also significantly associated with systemic inflammation, with every 1000 increase reducing high-sensitivity C-reactive protein levels by 13% and by 17% after adjusting for sedentary time (p=0.006 and 0.038, respectively). Systemic inflammation was not associated with sedentary time or MVPA, however.
Both activity variables and sedentary time were significantly associated with lung function, asthma control, and health status. The associations were weaker compared with those with exercise capacity and a greater increase in activity (>4000 daily steps or >25 minutes MVPA) was needed to have a clinically important difference, but the associations were “nonetheless statistically significant and biologically plausible,” says the team.
They conclude: “Our results highlight a need to develop and test interventions in patients with severe asthma that aim to improve exercise capacity and systemic inflammation by increasing walking and decreasing sedentary time, and improve asthma control by increasing the volume of MVPA.”
By Lucy Piper
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