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  • Research Roundup: Physical Inactivity Pandemic Takes Center Stage

    You don't need to tell physical therapists (PTs) and physical therapist assistants (PTAs) that physical activity is key to a healthy life and lower overall health care costs, but now a new batch of studies shines a light on that concept in ways that are grabbing the broader public's attention.

    Over the last week, 4 studies emerged—3 published in the Lancet, and a fourth in the European Journal of Preventive Cardiology—that show a direct connection between physical activity (PA) and mortality risk, and begin to quantify the global costs of low levels of PA. The results, some based on long-term studies with large participant numbers, are unequivocal in their conclusions about the very direct effect PA has on living longer.

    Here's what the 4 studies found:

    Engaging in 60-75 minutes of moderate-intensity physical activity for every 8 hours spent sitting virtually erases the mortality risk associated with sitting—and every little bit of PA helps help to offset the risk somewhat. This Lancet study (abstract) gained the widest attention, and was featured in major media outlets including CNN, US News and World Report, and National Public Radio.

    To reach their conclusions, authors conducted a meta-analysis of 16 studies that included 1 million participants in research that compared all-cause, cardiovascular-related, and cancer-related mortality with time spent sitting, watching television, and engaging in moderate-to-high PA. Bottom line: researchers found "a clear dose-response association" with "an almost curvilinear augmented risk for all-cause mortality with increased sitting time in combination with lower levels of activity."

    Using the most active (60-75 minutes per day of moderate intensity PA) and least sedentary (less than 4 hours per day sitting) group as a referent, researchers found mortality rates at 2-18 years 12% to 59% higher for individuals who sat more than 8 hours per day and engaged in minimal PA. The hazard ratios sloped neatly down as activity increased, with the group engaging in 25-35 minutes of moderate intensity PA per day—amounts more in line with national recommendations—receiving nearly the same benefit as the most active group. Those general patterns were also reflected in analyses of mortality related to cardiovascular conditions and cancer.

    Researchers also conducted a similar analysis of studies that focused on television-watching time and PA, and found that the relationship between television-watching time and all-cause mortality "seemed to be stronger in magnitude" but followed the same basic pattern.

    A long-term study of middle-aged men finds that low aerobic capacity is second only to smoking in its association with all-cause mortality. In a study that spanned 50 years, researchers from Sweden concluded that low aerobic capacity has a very solid link to increased risk of death—and not just from cardiovascular-related conditions, but from nearly every noncommunicable disease-related cause of death, save gastrointestinal conditions.

    The study, featured on Fox News, the Huffington Post, and Today online, was based on an analysis of 792 men born in 1913 in Gothenberg, Sweden. As part of a 50-year study of health, researchers analyzed the aerobic capacity (VO2 max) of the men in 1963 and again in 1967, and authors of the most recent study analyzed those results with mortality through 2012. After grouping the men into low, medium, and high VO2 max categories, researchers found that the low group had a 21% higher risk of dying prematurely than the middle group, and a 42% higher risk than the men in the top VO2 max category.

    The relationship was second only to smoking as a predictor of early mortality, according to authors. Interestingly, researchers found no significant association with death from certain kinds of conditions, including cardiovascular issues. Instead, they identified a relationship between low VO2 max and a wide range of mortality causes, from cancer to urinary tract disease, with the only exception being death related to gastrointestinal conditions. "This … suggests that cardiovascular fitness might be an advantage in most illnesses that can lead to death, and thus a benefit for general health and not only for cardiovascular health," authors write.

    Physical inactivity is costing the world at least $67.5 billion a year, and that burden falls in disproportionate ways. The Lancet published an article from researchers from the University of Sydney in Australia (abstract) who analyzed 2013 health data from 142 countries—representing 93% of the world's population—to estimate the costs of physical inactivity in terms of health care costs, productivity losses, and disability-adjusted life-years (DALYs), and to establish how those costs were borne out around the globe.

    The answer: physical inactivity's costs equal the total gross domestic product of Costa Rica, and the burden falls more heavily on individuals in developing countries, even though prevalence of physical inactivity is lower than that of more developed countries—for now.

    As reported in CBS news and elsewhere, authors of the study estimate that the $67 billion in costs represents payments of $31.2 billion from the public sector, $12.9 billion from the private sector, and $9.7 billion by households, accompanied by $13.7 billion in productivity losses. According to authors, physical inactivity was responsible for 13.4 million DALYs worldwide in 2013.

    Excluding productivity losses, physical inactivity was responsible for more than $600 million in health care costs in Africa, $3.2 billion in Latin American and the Caribbean, $25.7 billion in North America, $2.4 billion in the eastern Mediterranean region, $11.7 billion in Europe, $900 million in southeast Asia, and $9.2 billion in the Western Pacific region.

    Although individual households were linked to the smallest amounts paid in relation to physical inactivity, that $9.7 billion amount fell disproportionately to less developed regions, particularly in southeast Asia where nearly half of the physical inactivity-related health care costs were paid out-of-pocket. Authors believe that disproportionate impact is further reflected in DALYs rates, with southeast Asia accounting for 20% of the DALYs globally but only 1.7% of the direct costs.

    "We show that although inactivity is more prevalent in high-income countries, most of the health burden is in low-to-middle income countries," authors write. "As such countries develop economically, so will the consequent economic burden, if the pandemic of physical inactivity spreads as expected."

    Globally, we're getting better at tracking physical inactivity rates—but we're not doing enough to actually fight the pandemic. In the second in a series of inactivity report cards timed to coincide with the Summer Olympics games, the Lancet follows up on its 2012 look into how the world is responding to increasing rates of physical inactivity (abstract). The results? As reported in Science Daily and other outlets, authors say we know more now than we did in 2012—but that doesn't mean we're doing much about it.

    According to the authors of the series, while the number of countries tracking physical inactivity is higher than in 2012 (142 countries in 2016, compared with 118 in 2012), and 80% of countries have national physical activity policies or plans, only 56% reported operational policies or plans, and many of those are insufficient. Meanwhile, the global prevalence of physical inactivity is estimated to be 23% for adults and 80% for school-going adolescents.

    The lack of progress is most distressing in what authors describe as low-to-middle-income countries (LMICs), where population and physical inactivity rates are both increasing. Researchers note that the increased documentation is pointing out a problem that many LMICs simply aren't prepared to fix.

    "Progress on physical activity has been far from proportionate to the documented burden of disease from physical inactivity in countries of all income levels," authors write. "LMICs are laying the groundwork for effective public health action on physical activity, but it is not clear where the resources will be round to scale up effective interventions, build a physical activity workforce in public health, expand research in LMICs, and take bold initiatives that will increase physical activity in all countries."

    APTA offers multiple resources on the role physical therapists (PTs) and physical therapist assistants play in addressing prevention and wellness, including a 2-part podcast on the inactivity epidemic (part 1, part 2), and a recorded presentation on physical activity and the PT.

    Research-related stories featured in PT in Motion News are intended to highlight a topic of interest only and do not constitute an endorsement by APTA. For synthesized research and evidence-based practice information, visit the association's PTNow website.

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