What’s the best ‘dose’ of physical activity to gain mortality benefit in COPD?


By Michael Woodhead

8 Mar 2018

People with COPD can gain substantial mortality benefits from small amounts of exercise, even if they can’t achieve recommended physical activity levels, a new study shows.

After finding a linear dose-response relationship between physical activity and mortality in COPD patients, Australian researchers say the message should be that even a modest amount of activity such as walking can confer mortality benefit.

In a study of 2398 people who met the GOLD spirometric criteria for COPD, they found that after 8.5 years follow up there was a 45% reduction in all cause mortality and a 55-60% reduction in respiratory mortality risk among those who were ‘sufficiently active’ compared to those who did no activity.

Sufficiently active was defined as ≥7.5 metabolic equivalent  hours/week of physical activity.

However, they also found that people who achieved only got half way to achieving recommended levels of activity still showed a 25% reduction in all-cause mortality and an almost 50% reduction in cardiovascular mortality.

The reductions in mortality were apparent for activities such as walking and structured exercise  but not for domestic activity such as gardening.

The researchers, led by physiotherapist Sonia Wing Mei Cheng from Sydney University, said their findings highlighted the protective benefits of exercise at levels considerably lower than those currently recommended.

Many people with COPD would be unable to participate in vigorous physical activity or sport, but could be given advice to do moderately brisk walking for at least 75 minutes per week, which would give them a substantial mortality benefit, they suggested.

“Walking … is an achievable and accessible type of physical activity. It requires no specialised exercise equipment and, in the form of ground walking or treadmill walking, is commonly undertaken as part of pulmonary rehabilitation programs with good effect,” they noted.

“People with COPD may benefit from engagement in low levels of physical activity, particularly walking and structured exercise,” they concluded.

“Our results reinforce the importance of promoting regular physical activity as part of routine management of COPD, and the need for effective strategies to increase physical activity in this population.

The study is published in BMC Public Health.

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