Spending long hours sitting in the office or in front of the television not only increases the chances of gaining weight, but is also considered a key risk factor for health problems. Now, a new study has found an ally to counteract the chair effect, as it shows that increasing the number of steps per day can become an antidote to the negative effects of staying still for too long.
The research was carried out by experts from the Charles Perkins Centre at the University of Sydney, who analysed 72,174 people and found that taking around 10,000 steps a day is associated with a 39% reduction in the risk of death and a 21% reduction in the risk of developing cardiovascular diseases, regardless of the amount of time spent sedentary.
Previous studies have already established a link between higher daily steps and lower levels of mortality and cardiovascular disease (CVD), as well as between high levels of sedentary behaviour and an increased risk of CVD and death. However, this study is the first to objectively measure – using wrist-worn devices – whether daily steps can counteract the health risks of high sedentary behaviour. Their findings have been published in the British Journal of Sports Medicine.
“This is by no means a blame-free letter to people who are sedentary for excessive periods of time; however, it does contain an important public health message that every movement counts and that people can and should try to offset the health consequences of unavoidable sedentary time by increasing their daily step count,” said lead author Dr Matthew Ahmadi.
Professor Emmanuel Stamatakis, Director of the Mackenzie Wearables Research Hub at the Charles Perkins Centre and also an author on the paper, said: “Step counting is a tangible and easily understandable measure of physical activity that can help both the general population and healthcare professionals to accurately monitor physical activity. We hope that this evidence will inform the first generation of device-based guidelines on physical activity and sedentary behaviour, which should include key recommendations on daily walking.”
Reduction in mortality and cardiovascular events
The researchers used data from 72,174 individuals with an average age of 61 and 58% of whom were women from the UK Biobank study (a major biomedical database). These individuals wore an accelerometer device on their wrist for seven days to measure their physical activity. The accelerometer data was used to estimate daily number of steps and time spent sedentary, i.e. sitting or lying down while awake.
They then followed the participants’ health trajectories by linking hospitalization data and death records. The participants’ median daily step count was 6,222 steps/day, and 2,200 steps/day (the lowest 5% of daily steps among all participants) was used as a comparator to assess the impact on death and cardiovascular events with increasing step count.
The average time spent sedentary was 10.6 hours/day, so study participants who were sedentary 10.5 hours/day or more were considered high sedentary, while those who spent less than 10.5 hours/day sedentary were classified as low sedentary.
“Every movement counts and people can and should try to offset the health consequences of unavoidable sedentary time by increasing the number of steps taken daily.”
Factors that could influence the results were taken into account, and participants who were in poor health, underweight or had a health event within two years of follow-up were excluded. The researchers also took into account factors such as age, sex, ethnicity, education, smoking status, alcohol consumption, diet and parental history of CVD and cancer.
During a median follow-up of 6.9 years, 1,633 deaths and 6,190 cardiovascular events occurred. After accounting for other possible influences, the authors calculated that the optimal number of steps per day to counteract high sedentary time was between 9,000 and 10,000 steps/day, which reduced mortality risk by 39% and incident CVD risk by 21%. In both cases, 50% of the benefit was achieved between 4,000 and 4,500 steps/day.
As this was an observational study, a direct cause-and-effect relationship cannot be established, and although the large sample size and long follow-up reduced the risk of bias, the authors acknowledge the possibility that other unmeasured factors may have influenced the results. Furthermore, as steps and sedentary time were obtained at a single point in time, this could also lead to bias.
However, “Any daily step count above the reference of 2,200 steps/day was associated with lower mortality and incident CVD risk, for both low and high sedentary times. Accumulating between 9,000 and 10,000 steps/day optimized mortality and incident CVD risk reduction among highly sedentary participants,” the authors conclude.
