▎ WuXi AppTec content team editor
Regular physical activity is known to have many health benefits, but physical inactivity and sedentary behavior are still common globally.
Sedentary people tend to gain weight easily and increase the risk of diabetes, tumors and cardiovascular disease, which is supported by more and more evidence. However, the intensity of the association between physical activity and sedentary behavior and various associated clinical outcomes is unclear.
A recent study published in The Lancet Healthy Longevity found that higher physical activity and less sedentary behavior were strongly associated with better lower extremity muscle strength and had the least relationship to falls and upper extremity muscle strength. Compared to other indicators of physical activity, the number of steps was most correlated and most consistent with various clinical outcomes.
Screenshot source: The Lancet Healthy Longevity
Six systematic reviews involving a total of 1017 studies involving participants aged 60 to 92 years were included in the review. The researchers quantified the association between objective physical activity and associated clinical outcomes in the participants.
Indicators that reflect physical activity include steps, number of activities, overall duration of physical activity, duration of moderate to vigorous physical activity, duration of mild physical activity, and duration of sedentary length.
Clinical outcomes included mortality, weakness (e.g., fatigue, illness, and weight loss), overall cognitive function, fear of falls, falls, and fractures, muscle endurance, and muscle strength (e.g., upper extremity muscle strength, lower extremity muscle strength, and knee stretching). For the assessment of muscle strength and muscle endurance, the researchers used a stand-up and sit test (which effectively responds to functions required for daily life such as climbing stairs and walking) and a hand holding force test.
The results of the analysis found that the number of steps was the strongest factor associated with various clinical outcomes compared with other indicators of physical activity: for every 1000 steps increased in the number of steps, it was associated with an increase of 0.26 kg of hand strength, a reduction of 0.29 seconds to complete the 5 stand-up and sit tests, and a 0.19 point improvement in the simple cognitive function test.
The paper points out that the number of steps represents bipedal movement, which is a basic component of physical activity in our daily life. The number of steps can be easily increased by doing chores, walking daily, or taking public transportation.
More steps and moderate to strenuous physical activity contributed more to total physical activity than sedentary, and more steps were also associated with a higher proportion of low-intensity physical activity time. The researchers analyzed the participants' reduced steps and found that severe sedentary behavior was not only harmful to health, but also could have irreversible physiological consequences.
Image credit: 123RF
In addition to the number of steps, other factors strongly associated with clinical outcomes were, in order of associated intensity: moderate to intense physical activity, total physical activity, number of activities, mild physical activity, and sedentary behavior.
The above results also reaffirm that it is more beneficial to increase the intensity of activity as much as possible. Moderate to vigorous physical activity, which represents higher intensity activity, showed a stronger association with various clinical outcomes, while light physical activity and sedentary behavior showed the weakest association.
Of course, these results also highlight that any type of physical activity is associated with better health, and that exercise lasting longer and at higher intensities can produce decent results. This finding is also consistent with the recommendations of the 2020 World Health Organization guidelines: replace sedentary behavior with physical activity of any intensity, and 150 minutes of moderate to strenuous physical activity should be performed per week.
Since disability and chronic diseases are very common in the elderly population, this may limit their physical activity. Therefore, without emphasizing duration, frequency, and intensity, the recommendations in the study were more appropriate for those who were unable to perform 150 minutes of moderate-intensity to strenuous exercise. For those who are able to meet the weekly exercise intensity, it is also a reminder to keep the body moving as much as possible and avoid sitting still all day.
▲ Increasing the intensity of activity as much as possible is more beneficial to health (Image source: 123RF)
The paper concludes that emphasizing more walking is advantageous because the number of steps shows the greatest impact on a variety of clinical outcomes related to the skeletal musculature. Regardless of an individual's athletic ability, we emphasize the principle of "physical activity is better than nothing, it is better to be more active", encourage physical activity, and every step we take is important! These findings also provide further reference for public health and clinical practice studies.