Hi, we're now going to start the physical activity unit. With me today, we have Sneha and Margaret. Thank you so much for being here, and we're going to get going. So today I'm going to speak a bit about the epidemiology of physical activity and physical inactivity, or sedentary behavior, and the significance of physical activity in chronic disease and health. I want to start by doing a little bit of definitions in that when you look through the research, and kind of the emerging research over the past several decades. You see multiple terms used for physical activity. Sometimes used interchangeably, but we really think of as physical activity is any kind of movement that expends energy. As compared to the more historical or traditional definitions of exercise which is when you really speaking about kind of the exercise class or what was sort of thought of in the 60s and 70s. As like everybody goes to exercise class now. It's a repetitive bodily movement going back to old school calisthenics. So you can even imagine these are the kinds of things that you would do in PE in elementary school for jumping jacks, and those kinds of things. But the field is now focusing much more on physical activity as a much more broad classification of movements with direct health consequences. So we no longer have to think about taking exercise, but now think about trying to boost or increase physical activity more broadly in that can take many different forms. And so we'll go through some of those later on in today's talk. So I'm actually going to skip all the way to the end and then work back historically to kind of come up or to inform us to why we have the current recommendations that we do for physical activity. So currently, the National Physical Activity guidelines which are also paralleled by the World Health guidelines for physical activity are to actually get 150 minutes per week of moderate intensity physical activity. Meaning physical activity that elevates heart rate or has a bit of a cardiovascular component to it and to muscle strengthening days. Or 75 minutes of vigorous intensity and vigorous-intensity physical activity is defined a bit differently. So now we're looking to increase heart rate and breathing to a significant extent as compared to the moderate extent with the 150. So it's really a matter of volume and intensity for this equation or a combination of these two. So kind of tricky in terms of what is moderate, what is vigorous. 75 minutes of vigorous would potentially do it to meet this threshold of recommendation or 150 is something a little bit more moderate. And I'm going to talk a little bit more about what is classified as moderate, what is classified as vigorous and then the muscle strengthening days. It's kind of a different classification altogether or it can be combination. So already what are we getting out of this definition? >> It's pretty subjective like maybe something that's like sufficient to increase heart rate for one person noticeably might not be- >> Absolutely. >> the same for another person. >> Absolutely, definitely. >> Really like custom. Mm-hm, mm-hm. Yeah. >> Also, I feel like you can be strengthening your muscles while doing some of these other cardio things and that the overlap isn't really addressed. Absolutely, absolutely, right. And one thing that I kind of think of in reading this, too, is that it could potentially be confusing. And as we've talked about with other health behaviors and health recommendations, when confusion is entered into the equation then that tends to not be the most motivating approach. Okay. So here's where we are currently and I want to back up a little bit and explain a little bit more of what has informed this and why. And then think more broadly about how we, as public health professionals, can work with this to try to optimize health for the population. Okay, so backing up in terms of what this all means. This is a bit, this might look a little bit familiar, I'm now trying to approximate the food guide pyramid, but trying to cut down on these things at the top of the pyramid. And up there it says sitting computer time, screen time, and so on. Every day trying to boost small areas of physical activity that we might not even think about, so trying to climb stairs instead of taking the elevator. Trying to park farther away from the doors of buildings that we need to approach instead of driving around looking for the closest parking space and things of that nature. Also trying to fit in recreational activities, which many of which already have like a cardio type of component, and then also a few times working on stretching or yoga and strength activities for muscle building. So this is kind of a little bit simpler way to present the recommendations with respect to the number of minutes per week and the frequency in which you might engage in these behaviors. So I also want to talk a bit about about the history and how we got to the current recommendations for physical activity. And then what we know about them and then also introduce a little bit about what we really don't know, and also give a little bit of context for why it is so complicated. So until recently, exercise science was really spent focusing on sport and fitness. That's kind of what the field focused on but now public health has really embraced physical activity as something that we know really influences health behaviors or health and mortality. The way things have kind of gone is that originally the field was focusing on this high intensity exercise, the repetitive, very kind of sanctioned X number of reps or whatever, and now focusing more broadly on this moderate level of physical activity. So anything that's actually getting people up and moving and doesn't necessarily need to be X number of cardio minutes, or X number of muscle strengthening. But anything, we're looking at the entire activity spectrum. And now we're also including physical inactivity or sedentary behavior as being an area of focus. So while kind of simultaneously trying to encourage physical activity also recognizing that sedentary activity itself is a risk factor. And you'll also see things like active living or lifestyle activity which focuses more on these kinds of things like recreational activity or even work activity that is geared towards boosting the collectivity more broadly. So now considering things like gardening and household activities, playing with children, walking or biking to work, all as ways to boost physical activity or to avoid avoid sedentary behavior, okay. So we're getting there. Also measurement has improved and I'm actually going to spend a little bit of time talking about the complications of measurement. You all know that measurement is something that I study and I'm very interested in. But it's physical activity, I'll tell you right now, is so hard to measure and it's kind of interesting because physical activity is something that technically is observable. It's not something that we have to necessarily rely on people's interpretation of what we mean by it, we could follow somebody around for an entire day and get an idea of what their physical activity level is. And yet since it's impossible to follow everybody around all day in epidemiologic research. We have to rely on people's report of how much activity they're getting and it's tricky, it's really hard and I'll show you a little bit of why that is in a few minutes. But because we have gotten a bit better and have thought to measure physical activity. It's now included in a lot of our large-scale at the studies, and there are at least a few items in each of the large longitudinal studies that focus on physical activity itself. And therefore we're seeing it not only as a predictor and outcome measure but also as a significant which is excellent. Okay, so now going way back, I love memes and cats, Paffenbarger. This is a landmark study that found the bottom line is that physical activity boosts longevity, can actually lengthen the lifespan. And so this was done in the college alumni health study with alumni from Harvard and Penn, where it was actually several tens of thousands Harvard alumni who were followed for up to 16 years. And actually found that those alumni who spent 2,000 or more kilocalories a week, so that translates and depending on the type of exercise, potentially to about four hours, really depends on the kind. But anywhere between three and four hours of calisthenic type of exercise per week actually achieved longer lifespan. So that by, to the tune of one to two years of longer life as a function when they control for everything else to physical activity itself. So this was obviously pretty significant breaking news at the time, that regular exercise can actually translate to observable improvements in life. So this- >> It's interesting because it's a very large age group 35 to 74. Yeah, 35 to 74, yeah. Yeah, and they also see death rates decline steadily as energy expended on activity increased. So we're actually seeing a dose response for this as well. >> And so it's for every hour that you exercise that leads to two to three more years of life? >> Hours of life, to every hour exercise led to two to three hours of life and you're kind of like that do the math or reduce it down. So if it was around four hours of exercise per week that ultimately translated to, over the course of these years, translated to one or two more years of life. >> Wow. >> Yeah.