Recent results from the pioneering ALSPAC or Children of the 90s study show that too much sedentary time and too little exercise can have alarming effects on cardiovascular and metabolic health already at a young age. The good news is that they can be reversed by increasing light everyday exercise. Dr Andrew Agbaje explains the findings and why physical activity guidelines need an update.
Listen to Dr. Agbaje’s podcast interview:
Ulla: Hi everybody, this is Ulla Kaltiala from the University of Eastern Finland communications, and I'm here with Dr. Andrew Agbaje, who has some alarming findings on the lack of physical activity in childhood. You may also be surprised to hear what kind of exercise is actually best for our children and youngsters.
Ulla: Let's start with an introduction. Who are you and what do you do?
Andrew: My name is Andrew Agbaje. I'm a physician and also a pediatric clinical epidemiologist at the Institute of Public Health and Clinical Nutrition, University of Eastern Finland. I am also the principal investigator of urFIT-Child research group, and I also have an honorary position at the University of Exeter in the UK. So my overall study topic here in the University of Eastern Finland, where I conduct research and teach, is also the name of my research group, which is Understanding fitness and cardiometabolic health in little darlings (urFIT-child).
Ulla: So why is it important to study this topic?
Andrew: Well, we now know that diseases like obesity, diabetes and cardiovascular diseases actually start in childhood and they are preventable diseases that lifestyle modification can actually address. But what we still do not know yet is the interrelationship between body composition, insulin resistance, physical activity that are actually measured with gold standard. Also, measuring these in a very large group repeatedly over a long period of time is not quite common. For that reason, we have not been able to have adequate understanding of this relationship between these factors and how and when is the best time to actually prevent metabolic and cardiovascular disease. For example, in several countries, cholesterol level is often checked based on their guideline at about the age of 40 and above. Considering that, well, youngsters are healthy, so there's no need to check their cholesterol level. But we have found out that an increase in cholesterol level in adolescents might actually, was actually associated with an increased risk of heart damage, even in mid 20s, almost two decades earlier than what conventional guidelines actually recommend. For this reason, we actually recommended an adolescent cholesterol passport as a preventive strategy in the young population.
Ulla: How would such a cholesterol passport work?
Andrew: I believe that we do know about vaccination cards and immunization cards. So something like that. It does mean that adolescent about the age of 15 to 17 are invited to the health care center and their cholesterol levels are checked. And then when that is done, if there is an elevated cholesterol level, such adolescents are invited to actually repeat this measure again, maybe after six months. And if it remains persistently high, then the doctors may be invited or the adolescent may be sent to the doctors for specific health advice and possibly management. But if everything is fine, then you can come back in ten years time. So this actually gives us this preventive mindset. And this card or this passport is the documentation of your cholesterol level. So you can say, okay, everything is fine, and then just go away.
Ulla: That sounds good. So who are the children and young people you have studied?
Andrew: Well, my research is based on a strong international collaboration between the University of Eastern Finland, the University of Exeter in the UK, the University of Bristol in the UK. The data for my research is from the children of the 90s, also known as the Avon Longitudinal Study of Parents and Children, which started over 30 years ago in England. More than 15,000 mothers were actually invited when they were pregnant. And as soon as they gave birth to these children, the children were enrolled. These children are known as the children of 90s, some of them more than 30 years ago. So these children now have been growing, and then they've been coming to the clinic for experimentation, and then data have been collected from them. So repeated measures have taken place from birth at the age of 7, 9, 10, 11, 13, 15, 17 and 24. Currently, the 30th year follow up clinic visit is ongoing. So we have three generations. We have the mothers and the fathers of these children of the 90s. We also have the children of the 90s themselves. And then we also have the children of the children of the 90s. That's quite interesting. And new data appears to be collected now in the children of the children of the 90s. My research in Finland actually focuses on the children of the 90s between the age of about 7 to 9 and 24 years data and that's what I've been using. So having this data in more than 14,000 children is not quite common.
Ulla: So how did you get reliable data on their physical activity?
Andrew: Well, due to the foresight of 84 year old professor Jean Godin from the University of Bristol and a team who acquired several thousands of accelerometer devices several years ago and utilized it in capturing the physical activity and sedentary time of the children of the age of 11, 13, 15 and also at 24 years. They somehow knew afore time that a time would come when we would not actually like to use questionnaire based physical activity measurement simply because it's not reliable. So they wanted to find out, what else can we use to actually reduce the bias, like recall bias, that questionnaire assessment of physical activity may lead to. So this helped capture time spent in light physical activity or light exercise, time spent in moderate to vigorous physical activity, and also time spent sedentary. And because of this strong collaboration, I was able to request for this longitudinal data from them. And this data helps us to answer some of the research questions and the knowledge gaps that have been identified by the World Health Organization as it pertains to physical activity in children and adolescents.
Ulla: What else was measured and what were you looking at?
Andrew: So we measured several metabolic parameters. We measured, several cardiovascular parameters were measured and so we are looking at how physical activity and sedentary time relates to body composition, body fat, muscle mass, blood pressure, insulin resistance, glucose level, vascular and cardiac structure and function, even liver fat and including some kidney function, metabolic function. So those were the things that were actually measured. But what is unprecedented about this data is that the availability of good standard measure helps us to provide better answer much more than what we have always had. And for the first time in the world, this high quality data made us publish a paper three weeks ago in Nature Communication on the relationship between physical activity and sedentary time and DEXA measurement of body fat.
Ulla: What did you find out about children's and young people's sedentary time and physical activity?
Andrew: Well, we found out that by the age of eleven years, time spent sedentary was about 6 hours per day and that when time spent in light exercise was about 6 hours per day, it was quite optimal because it looks as if it was cancelling out the time spent sedentary at the age of 11. However, by the age of 24, the balance was altered such that young adults spent about 9 hours per day sedentary and only 3 hours per day in light exercise. Well, moderate to vigorous physical activity appears to stay the same between 50 minutes to 55 minutes per day from childhood through young adulthood.
The World Health Organization has actually focused essentially on increasing moderate to vigorous exercise in children. And usually they often report that 80% of adolescents globally do not meet these 60 minutes per day of moderate to vigorous physical activity. Well, although participating in moderate to vigorous exercise has some benefit, our research shows that it is very unlikely to increase on a population level the amount of time spent in moderate or vigorous physical activity. Hence, there is need for us to shift our message to what might even be more important. So this serious and potentially costly misunderstanding of increasing moderate to vigorous exercise is also assumed as an optimal solution to sedentary time does not appear to be so. Importantly, all the increase in sedentary time was time lost in light exercise. And so if we increase moderate to vigorous physical activity without actually increasing light exercise, then we are not altering the balance that was already altered due to increased in sedentary time. So we discovered that light exercise may even be 5 to 8 times more beneficial than moderate to vigorous exercise in this young population and may potentially be able to reverse the negative consequence of sedentary time.
Ulla: How were the changes in sedentary time and physical activity linked to the changes in metabolic and cardiovascular health?
Andrew: Sedentary time includes sitting time, includes screen time, includes time spent watching TV, watching movies, playing video games, engaging in social media for a long time on phones and tablet. Those are also called screen time. Now, we found out that each minute spent sedentary actually increased body fat by about 1.3 grams from childhood through young adulthood. We have seen that other researchers have published among adults that one kg increase in body fat increases the risk of death by 60%. That is quite enormous.
Sedentary time from childhood also contributes 70% of the total increase in cholesterol level from childhood through young adulthood. We and other researchers have shown that an increased cholesterol level in adolescents increases the risk of heart attacks and strokes. We have shown increases the risk of heart damage by 30%.
Another thing we also discovered is that sedentary time from childhood to young adulthood amounted to 30% of the total increase in systolic blood pressure from childhood to young adulthood. And we have also discovered that an increase in systolic blood pressure increases the risk of heart attack or stroke or cardiac damage by between 40% to 60%. We also discovered that sedentary time increases inflammation and that inflammation may cause arterial stiffness and subclinical atherosclerosis. So accumulating 8 hours of sedentary time in adolescents was associated with a 10% increase in the size of the heart. Putting this together, sedentary time potentially causes fat-obesity, elevated blood pressure, worsening insulin resistance, increased inflammation, and enlarged heart. So what can we say? We can say that childhood adolescence sedentariness is a frightening monster of disease and premature death that needs to be avoided.
Ulla: That sounds really alarming. However, you said that these adverse changes could be even entirely reversed with physical activity. What kind of activity?
Andrew: Yes, well, that's a good news. Light exercise or light intensity physical activity completely potentially reverse the adversities of sedentary time. This light exercise can be accumulated about 3 to 6 hours per day, depending on people's time. But we understood, or we found out that 3 to 4 hours per day, was actually the minimum amount of time that we can spend in light exercise to actually reverse the effect of sedentary time. So light exercise reduces cholesterol level, reduces fat, reduces blood pressure, reduces inflammation, also improves heart function, and decreases inflammation.
So examples of light exercise includes outdoor games, playing in the playground, walking with dogs, running our errands for parents, going to the shopping mall, walking, not taking bus, walking and biking to school, strolls in the park, playing in the forest, gardening, casual basketball, golf ball, frisbee, those are examples. This light exercise just tries to break our sitting time, engage us in making a move so we don't sit down for too long. And some of this exercise might not even make us sweat. And it looks as if, well, is it really beneficial? I tell you it does.
Ulla: Did you see any health benefits from more strenuous exercise?
Andrew: Yes, we found some benefit with moderate to vigorous exercise. The only problem is that moderate to vigorous exercise, we don't spend so much of that time. We don't accumulate so much of moderate to vigorous exercise every day, so less than 1 hour usually. And for that reason, we don't see so much of its benefit. And also, physiologic fat in the body also dampens the effect of moderate vigorous exercise. It might interest us that in our study we have seen that participating in moderate to vigorous exercise does not lower blood pressure. Surprising to us. Surprising.
Ulla: How do these results challenge the present physical activity recommendations for children and adolescents?
Andrew: Thank you for that. Unfortunately, existing guidelines lack recommendation on light exercise. We have actually focused on moderate to vigorous exercise, which means that the only antidote to the catastrophic effect of sedentary time has been left out of our guideline. So this is a preventive and public health emergency. Guidelines have overwhelmingly emphasized on moderate to vigorous exercise. And majority of the evidence are actually cross sectional, and some of them, even based on questionnaire, are not accelerometer measurement that has been measured repeatedly for a long time. And this has raised serious controversies because now that this accelerometer based data are now coming out, there appears to be controversial in their result. For example, differentiating between the benefit of light exercise and the benefit of moderate to vigorous exercise.
It might interest us to know that meta-analysis of more than 140 clinical trials across the globe concluded that moderate to vigorous exercise did not significantly reduce BMI obesity. We can imagine how much money was spent in those trials, and the results were quite disappointing.
Well, because now we have accelerometer based measurement and our result appears to be challenging what has been known, many editors are not happy or they don't want to publish our paper because they feel like, well, this is challenging what we have always known. We feel like the more the better, but we are not seeing that. So it's quite a problem. So those are the challenges we have with this result.
Ulla: What exactly are the present recommendations and how should they be updated?
Andrew: So the current recommendation was very exact with moderate to vigorous exercise that is accumulating about 60 minutes per day on average in children and adolescents. Not too exact about sedentary time because there have been no evidence that actually captures the amount of time children actually spend sedentary. So this part has to be improved. Also, the recommendations do not measure light exercise at all because there have been no evidence.
So future recommendations for children and adolescent should include light exercise of 3 to 4 hours every day. Specific recommendation for sedentary time such that we can say, reduce sedentary time to at least 6 hours per day. Then recommendations should also not really focus on moderate to vigorous physical activity of 60 minutes per day and then start blaming the adolescents that they can't accomplish that. We have seen that from childhood to young adulthood on a population level, it is unlikely that they are going to achieve that. Rather, recommendations should tone down on 60 minutes because it is arbitrary. Somebody just said, well, I liked it, 60 minutes, 1 hour. Oh, looks nice, let's work on that. It's arbitrary. But what is realistic is 50 minutes of MVPA. We can revise our guideline to highlight that. So current recommendations need now to focus on light exercise specific time. We want to reduce sedentary time to less than 6 hours per day and also reduce MVPA moderate to vigorous exercise to about 50 minutes per day. I think that would be nice.
Ulla: So what can parents and society do to bring more movement into children's everyday lives?
Andrew: Well, when it comes to children and adolescents, we need to lead by example. That means if we want children to change their lifestyle, then parents don't sit down and be watching tv for 3 hours. So the family, it has to be a family, a home sort of change. Which means that the habit has to be developed and maintained by everybody in the family. Well, we discover that daycare and preschools appears to have more time in exercise. But when children get to school, older children, adolescents, because of classes, they sit more and they spend more time sedentary. It is possible that schools may be more flexible in their curriculum to accommodate compulsory exercise per day, every day, maybe an hour every day in the school, children should be able to engage in exercise. When it comes to parents and then the society. The society can provide safe walking and cycling environment, safe neighbourhoods, organize walking and hiking for children, for families, and things like disseminating exercise tips, creating these programs, establishing street by street exercise support groups that helps us to motivate one another to exercise more and by this, we can become our neighbours’ exercise keepers, creating a collective victory over sedentariness. That would be amazing.
Ulla: So a lot can be done, but it also requires a supportive environment. With so many interesting results already, what will be the next step in your research?
Andrew: Well, so we have identified a few benefits from light exercise and the consequences of sedentary time. But, you know, as we do know, that the body has lot of organs. So we still have to check what is the impact of sedentary time on the liver, on the kidney, on metabolic syndrome, and on some metabolic parameters, metabolomic parameters like apolipoproteins. So we hope that we have more fundings to do that so that we can comprehensively say that almost every organ of the body system might be damaged by spending time sedentary. But we can't say that now. But we can say that, let's say 50% to 60% of the organs in the body are damaged by sedentary time, but we need to find the remaining 40%. So those are the places where we are going to look at next.
Ulla: Well, I for one am looking forward to hearing more from your research. Dr. Andrew Agbaje, thank you for these useful insights, and thank you to our listeners.
Andrew: Thank you very much.
