Being more sedentary in childhood leads to a higher left ventricular mass in young adulthood, which is an independent risk factor for cardiovascular events. This was the key finding of a study presented at the recent European Society of Cardiology (ESC) Congress 2023 in Amsterdam.
The study also revealed that this increased risk occurred even in those with a normal weight and blood pressure.
The first study to investigate the cumulative effect of smartwatch-assessed sedentary time in young people and cardiac damage later in life, the researchers asked children aged 11 to wear a smartwatch with an activity tracker for seven days. This was repeated at 15 years of age and again at age 24.
Echocardiography which the imaging modality of choice to assess left ventricular end-diastolic and end-systolic volumes, was used assess the mass of the left ventricle. Measurements were undertaken at ages 17 and 24 years of age and reported in grams relative to height (g/m2.7).
Sedentary behaviour and left ventricular mass
The study enrolled 766 children (55% girls). At 11 years of age, the participants were sedentary for an average of 362 minutes a day. This rose to an average of 474 minutes a day in those 15 years of age, and further still to 531 minutes by age 24.
Sedentary time therefore increased by an average of 169 minutes or 2.8 hours per day between childhood and young adulthood.
The researchers calculated that each one-minute increase in sedentary time from 11 to 24 years of age, was associated with a 0.004 g/m2.7 increase in left ventricular mass between the ages of 17 and 24 years.
When multiplied by 169 minutes of additional inactivity, this equates to a 0.7 g/m2.7 daily rise – the equivalent of a 3 g increase in left ventricular mass between echocardiography measurements at the average height gain.
Study author Dr Andrew Agbaje of the University of Eastern Finland in Kuopio, Finland, said: ‘Children were sedentary for more than six hours a day and this increased by nearly three hours a day by the time they reached young adulthood.
‘Our study indicates that the accumulation of inactive time is related to heart damage regardless of body weight and blood pressure. Parents should encourage children and teenagers to move more by taking them out for a walk and limiting time spent on social media and video games’.