A study of almost 8 000 people found that becoming overweight or obese, and an increased risk of chronic disease, are the potential consequences of sitting for more than eight hours per day, unlike sitting for only four hours per day.
The cross-sectional survey of participants aged 20 to 65 (half of whom are women) from the Latin American Study on Nutrition and Health (ELANS), included representative samples from urban populations in Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Peru and Venezuela, reports Medscape.
The average time spent sitting was 420 minutes a day. Ecuador had the lowest time (300 min/d), and Argentina and Peru had the highest (480 min/d).
No amount of sitting time has been associated with a greater health risk, but the World Health Organisation recommends that sitting time be minimal.
"We used to believe that any intense physical exercise could compensate for a sedentary life. But now we know that a sedentary lifestyle in general and sitting time in particular have a direct effect on and are an independent risk factor for chronic diseases," said study author Irina Kovalskys, PhD, a paediatric specialist in nutrition and a professor of nutrition at the Catholic University of Argentina and a principal investigator of ELANS.
The 420-min average sitting time is worrying in a population such as the one studied, in which 60% of adults are obese and there are high rates of cardiometabolic risk factors. She said it was important to raise awareness among the population and focus on adolescents.
Felipe Lobelo, PhD, is a Colombian physician, an associate professor of global health at the Rollins School of Public Health at Emory University, and director of epidemiology at Kaiser Permanente Georgia, in Atlanta. He did not participate in this study but promotes the concept of exercise in medicine.
The activity of the patient must be included in a clinical setting, and improving the level of physical activity can have a positive impact on health prognosis, he said.
“During the pandemic, it was observed that more active people had a lower risk of dying or of being hospitalised from Covid-19 than less active people, independently of other factors, such as hypertension, diabetes and obesity.
“To make public health recommendations or even advise patients, a cut-off point is needed. Guidelines recommend 150 minutes per week of moderate to vigorous physical activity, and some countries have started to indicate that we should be concerned about people's sitting time. There is still no equivalent to the 150 minutes, therefore, these studies are important, especially in the Latin American population.”
The concept of an increased risk of death or chronic disease resulting from lack of physical activity had arisen in the past 50 years, he added, but only in the past two decades have we started thinking about sitting time.
"Spending more than eight hours sitting per day clearly causes a much higher risk of chronic diseases, including obesity and diabetes. It may be a continuous and progressive association, and the point at which this increase becomes exponential is clearly between six and hours hours of sitting time.”
The authors expected to find a linear association with risk for being overweight or obese after four hours, but they did not find one.
"This study has limitations. Among them was that other indicators were not considered, such as health indicators. Collaborations are starting with other research groups, and other studies are being designed," said study author Gerson Ferrari, PhD, an associate professor at the School of Sciences in Physical Activity, Sports and Health at the Medical Sciences Faculty of the Santiago de Chile University.
Comparing indicators
The Latin American study, which was published in BMC Public Health, tried to establish a sitting cut-off time after which the risk of becoming overweight or obese increases. It used three indicators of excess weight: BMI, waist circumference and neck circumference.
Sitting for more than eight hours increased the chances of excess weight by 10% when measured by BMI and by 13% when neck circumference was used.
Ferrari said the result obtained measuring BMI is the one that should be considered, because it is used in public policy. Neck circumference is a more recent measurement of detection and it is less studied, but it is a valid indicator, with good sensitivity and advantages over others, such as ease of measurement and lack of variation over time.
The study’s results indicate that measuring neck circumference may be the most sensitive method of the three. Neck circumference was proportionally greater in people who sat for ≥4, ≥6, and ≥8 h/d than in those who sat for < 4, < 6, and < 8 h/d. This relationship was not observed with the other indicators.
Broaching the topic
“What is important is uninterrupted sitting time. The recommendation is to break up those sitting times with active periods. Health professionals have already incorporated the concept of moderate to vigorous physical exercise, but non-intense activities are sufficient to reduce sitting time. Yoga may not be vigorous, but it is valuable at reducing sitting time,” said Kovalskys.
Ferrari recommended giving patients concrete messages so that they spend as little time possible sitting. “It is better to stand on the bus or train even when there is a place to sit. Are you going to talk on the phone? It is better to do it while walking or at least standing instead of sitting.”
Physical activity
Some studies suggest that more than 60 min/d of moderate-intensity exercise or more than 150 min/wk of moderate-intensity to vigorous exercise may be effective at mitigating the increased risk for mortality associated with sitting time, but reduced intensity may not be enough.
Interrupting sitting every 30 to 60 minutes to walk or cycle (two to 10 min), performing three minutes of simple resistance activities every 30 minutes, such as calf or knee lifts, performing intermittent leg movements (one minute of activity for every four minutes of inactivity during a three-hour protocol session), or pausing to climb stairs (five minutes every hour) may be beneficial for vascular health.
However, not all studies have demonstrated these positive effects, therefore, some populations may need exercise of greater intensity or duration to counteract the negative vascular effects of acute inactivity periods.
Standing workstations
Standing workstations are effective at reducing sitting time in offices but may be ineffective at reducing vascular alterations related to sitting time. Although some experimental studies indicate vascular benefits, epidemiologic studies suggest that long periods of standing can be harmful to vascular health, especially for venous diseases.
Recommendations for use should be accompanied by specific regimens on the frequency and duration of the position to attain the maximum benefits and minimise other vascular complications.
One problem noted by Lobelo is that some doctors ask their patients how active they are, but they do so in a non-standardised manner
He said that “an advantage of having physical activity as a vital sign in patient records is that it allows us to identify those who are at greater risk”.
Kaiser Permanente asks the following questions: how many minutes of physical activity do you perform regularly per week, and what is the average intensity of that activity? Patients can be classified into three groups: those who follow the recommendations, those with almost no activity, and those who perform some physical activity but do not meet the recommended 150 min/wk of moderate to vigorous activity.
Recording sitting time is more difficult. Lobelo said it is easier for a person to remember how much time they spent running than how long they were sitting.
On technology, he said most watches provide a good estimate. Without technology, it can be estimated by asking how much time is spent in the car, on the bus, or in front of the computer or television and then adding up these times.
The two behaviours, lack of physical activity and excessive sitting time, have independent associations with health outcomes, he said. But if both are combined, the risk of obesity, diabetes, and cardiovascular diseases is not just added but rather is multiplied.
These behaviours contribute to the epidemic of obesity and diabetes, since most people do not follow either of the two recommendations.
“Studies show that of the two behaviours, the more negative for health would be not following the physical activity recommendations,” he said. “If the recommendation of 150 min/wk of moderate to vigorous physical activity is followed, the associated risk of sitting too much declines by 80% to 90%.
“Additionally, we can prevent, help to manage, and decrease the risk of complications in more than 100 diseases, including infections.
Study details
Are the different cut-off points for sitting time associated with excess weight in adults? A population based study in Latin America
Eduardo Rossato de Victo, Irina Kovalskys, Adilson Marques & Gerson Ferrari et al
Published in BMC Public Health on 16 January 2023
Abstract
Background
Excess weight is increasing worldwide, and in Latin America more than half of the population is excess weight. One of the reasons for this increase has been excessive sitting time. Still, it remains to be seen whether there is an excessive amount of that time in Latin American adults. This study aimed to associate different sitting time cut-off points with the excess weight.
Methods
Data from the Latin American Study of Nutrition and Health (ELANS), a cross-sectional population-based survey conducted in eight Latin American countries, were used. The excess weight indicators used were body mass index, and waist and neck circumferences. Sitting time was obtained using questionnaires and categorized at different cut-off points. Differences between sitting time categories (< 4 or ≥ 4; < 6 or ≥ 6; and < 8 or ≥ 8 hours/day) and excess weight were obtained by Student’s t test for independent samples and the association between sitting time categories and different indicators of excess weight were obtained by logistic regression.
Results
The median of the sitting time was 420 min/day (IQR: 240–600). There were no significant differences between body mass index (kg/m2) and waist circumference (cm) with categories of sitting time. The mean values of neck circumference (cm) were significantly higher in ≥4, ≥6 and ≥ 8 hours/day than < 4, < 6, and < 8 hours/day of sitting time in the pooled sample. Some distinct differences by country were observed. There were significant differences among excess weight by body mass index (63.2% versus 60.8) with < 8 vs ≥8 hours/day of sitting time. The proportion of excess weight by neck circumference was higher in participants who reported ≥4, ≥6, and ≥ 8 hours/day compared to < 4, < 6, and < 8 hours/day of sitting time. Considering ≥8 hours/day of sitting time, higher odds of excess weight were found evaluated by body mass index (OR: 1.10; 95% CI: 1.01, 1.20) and neck circumference (OR: 1.13; CI 95%: 1.03, 1.24) overall.
Conclusions
Sitting time above 8 hours/day was associated with higher odds of excess weight, even though there were no differences in waist circumference between sitting time categories.
Medscape article – What Happens If We Sit for More Than 8 Hours Per Day? (Open access)
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