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Regular physical exercise associated with gathering food, hunting and simply walking long distances was a natural part of human lifestyles for thousands of years and has been identified as a hallmark of the lifestyle of centenarians in several Blue Zones around the world. However, in today’s busy world, already packed with long working hours, long commutes, business travel and especially for women taking care of children, the opportunities for physical activity have been greatly reduced.

Unfortunately, regular physical exercise has almost vanished from the lifestyle of a large percentage of the US population and has been replaced by a predominantly sedentary lifestyle. As mentioned in a previous post by E. Dylan Mayer, “The shocking news is that adults in the US spend nearly 80% of their waking hours in a sitting position, spend about 20% engaged in light intensity physical exercise, like walking, and only 1.5% in moderate to vigorous exercise like running or weightlifting.” This lack of physical exercise has been implicated as an important lifestyle factor that affects health, body weight and longevity. Previous research has suggested that being very inactive, like sitting for over 10 to 14 hours a day, can increase the risk of death and heart disease by 30% to 50%.

“…simply walking an extra 1000 steps each day can lower the chance of dying early by 6% to 36% and reduce the risk of heart disease by 5% to 21%.”

There is growing scientific evidence that regular physical exercise as assessed by counting the number of daily steps has significant positive effects on cardiovascular (CV) disease, CV mortality and overall mortality, regardless how much time you spend in a sedentary activities. A recent systemic review and meta-analysis by Katherine S. Hall and colleagues which was published in the International Journal of Behavioral Nutrition and Physical Activity in 2020 looked at 17 studies that included over 30,000 adults. Their results showed that simply walking an extra 1000 steps each day can lower the chance of dying early by 6% to 36% and reduce the risk of heart disease by 5% to 21%. The authors showed that these benefits were seen regardless of the person’s age, sex, and health conditions, or lifestyle habits like drinking alcohol, smoking, or their diet.

Not surprisingly, both the amount you exercise (number of steps you take daily) and how much you sit can influence factors that increase the risk of heart disease and death, like being overweight, high blood pressure, and cholesterol levels. Some studies suggest that being physically active reduce the risks linked to sitting a lot. For example, 60 to 75 minutes of moderate to vigorous exercise each day can significantly lower the negative effects of sitting most of the day.

However, no research has yet looked specifically at whether sitting too much can change the relationship between daily steps and the risk of dying or getting heart disease. To answer this question, a research team from the University of Sydney, Australia looked at a large group of adults in the UK, using wrist-worn devices that track movement and published their findings in the British Journal of Sports Medicine. Quantifying daily physical activity with such wearable devices is a more objective and accurate measure than self-reports of daily exercise. The goal of this study was to figure out if the time spent sitting changes the ideal and minimum number of daily steps needed to lower the risk of death and heart disease.

“…lowest daily exercise level associated with all-cause mortality ranged between 9000 and 10 500 steps/day for individuals with high and low sedentary time.”

Among 72,174 participants (mean age=61years), 1633 deaths and 6190 CVD events occurred over an average of 7 years of follow-up. Compared with the referent 2200 steps/day (5th percentile), the lowest daily exercise level associated with the lowest all-cause mortality ranged between 9000 and 10 500 steps/day for individuals with high and low sedentary time. For CVD, the lowest risk was observed at approximately 9700 steps/day both for the high and low sedentary time groups. The minimal dose (steps/day associated with 50% of the optimal dose) of daily steps was between 4000 and 4500 steps/day across sedentary time groups for all-cause mortality and CVD. Surprisingly, the amount of time spent in sedentary activities, e.g. sitting on a desk or in front of a computer screen did not significantly modify the dose-response association of daily steps with disease and mortality.

Importantly, the authors concluded that any amount of daily steps above 2200 steps/day was associated with lower mortality and incident CVD risk, regardless of how much time the individuals were engaged in sedentary behavior. Accruing 9000–10 500 steps/day was associated with the lowest mortality risk independent of sedentary time. However, for a roughly equivalent number of steps/day, the risk of incident CVD was lower for the group that spent less time in sedentary activities than the group with high sedentary time.

“…any amount of exercise above the minimum of 2200 steps/day is beneficial…”

To get a better idea of what time is required to achieve the optimal health outcomes, it’s suggested the average person walks about 100 steps per minute – which would mean it would take a little under 30 minutes for the average person to walk a mile. So in order for someone to reach the 10,000 step goal, they would need to walk between four and five miles a day, which amounts roughly to two hours of physical activity, which is obviously not realistic for a large number of people. The results from the Ahmat study, suggesting that any amount of exercise above the minimum of 2200 steps/day is beneficial, is good news for individuals that do not have the time available to walk 10,000 steps per day.

Based on an earlier research study performed by Diaz and colleagues, previously reviewed in this blog by Dylan, and based on an extensive body of research, these authors recommend a simple, individualized, and flexible lifestyle modification:

“The recommendations are broken down into two categories: moderate to vigorous exercise and interruption of sedentary time. The exercise component includes a recommendation of 3-5 days per week of moderate to vigorous aerobic exercise, like running, resistance training and power yoga for a duration of 20 – 60 minutes, which is more realistic for the average working individual. The authors also recommended regularly interrupting sedentary behavior with brief bouts of movement. The goal is to be sedentary for less than 9.5 hours per day, with movement of any intensity (more intense, the better) every 30 minutes for any duration (the longer, the better).

“…it may be as important for your health as eating a healthy diet and getting a good night’s sleep.”

In summary, if you weren’t aware of these startling numbers, this information may make you want to reconsider your daily routine at work or during studies: introduce frequent interruptions into your schedule in the form of going up and down the stairs, walking around the block or just get up for a few minutes and stretch. If pursued on a regular basis in addition to your daily workout schedule, it may be as important for your health as eating a healthy diet and getting a good night’s sleep. Obviously, following all three of these lifestyle modifications and walking for 2 hours on the weekends gives you the maximal benefit.”