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Physical activity, sedentary behavior, and health: paradigm paralysis or paradigm shift?

Katzmarzyk PT - Diabetes (2010)

View Article: PubMed Central - PubMed

Affiliation: Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA. peter.katzmarzyk@pbrc.edu

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One potential example of this phenomenon could turn out to be the continued focus on moderate and vigorous physical activity as the dominant health-related aspect of human movement... However, if we are complacent with the existing paradigm—that increasing levels of moderate and vigorous levels of physical activity will result in the greatest improvements in public health—then we may not obtain the full return on investment with respect to improving quality of life and life expectancy through patterns of human movement... Emerging evidence for the role of sedentary behavior on health, which may be independent of physical activity per se, finds us at a crossroad with respect to prescribing optimal daily human movement patterns for health... However, the biological, social, and environmental pathways leading to sedentary behavior versus physical activity may be different... Further, the health effects associated with sedentary behavior and physical activity may be the result of different biological mechanisms... A negative consequence to the observed improvements in energetic efficiency is the proliferation of health concerns that are related to low levels of physical activity and/or high levels of sedentary behavior... The results of these three studies are remarkably similar; however, two other studies have shown somewhat different results... An analysis from the ACLS found a significant positive relationship between time spent sitting in a car and CVD mortality in men, but failed to show a relationship between TV viewing and CVD mortality... These postural changes do not reflect many typical sedentary behaviors performed by free-living humans, such as sitting... However, results from the study by Lipman et al., where the investigators immobilized monkeys in an upright position, showed significantly decreased glucose tolerance in immobilized monkeys compared with control animals, suggesting that the effects were caused by the inactivity per se as normal gravitational effects were maintained... For example, removal of intermittent standing and ambulation in rats by hind limb suspension (unloading) results in marked decreases in lipoprotein lipase (LPL) activity (the enzyme responsible for hydrolysis of triglyceride-rich lipoproteins), triglyceride uptake into red skeletal muscle, and reductions in the concentration of HDL cholesterol within a day's time... Importantly, these rapid effects operate through a process that markedly reduces LPL protein and activity without affecting LPL mRNA concentration, whereas both exercise (>twofold increase) and continuous chronic inactivity (>threefold decrease) impact LPL mRNA... The current public health recommendations for moderate and vigorous physical activity are the result of more than 60 years of scientific inquiry that has produced evidence for a causal link between physical activity and health... On the other hand, sedentary behaviors (<100 accelerometer counts per minute) account for ∼55% of an American's typical day... We must begin to explore novel approaches to reduce the widespread exposure to sedentary behaviors, as the potential health benefits to be gained could be substantial.

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Average steps per day among Old Order Amish men and women (12) compared with contemporary U.S. adults in the 2005–2006 U.S. NHANES (13) and the 2003 America on the Move Study (14).
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Figure 1: Average steps per day among Old Order Amish men and women (12) compared with contemporary U.S. adults in the 2005–2006 U.S. NHANES (13) and the 2003 America on the Move Study (14).

Mentions: Modern humans in the Western world have relatively low levels of physical activity compared with contemporary hunter-gatherers. Hayes et al. (9) reported that the total energy expenditure/resting energy expenditure or Physical Activity Level (PAL) among subsistence-level human populations approximates 3.2, while among representative humans living in contemporary society, the PAL is ∼1.67. The impact of the transition from a semi-subsistent existence to a Western lifestyle on physical fitness levels are exemplified by work in an Inuit community (Igloolik, northern Canada) (10,11). Studies in the population from 1970 through 1990 demonstrated marked reductions in average aerobic fitness (ml · kg−1 · min−1) over time in all age-groups (10,11). Recent work among Old Order Amish living a traditional agricultural lifestyle indicates that this population engages in more daily movement than contemporary Americans. The average number of steps per day taken by Amish men and women were 18,425 steps per day and 14,196 steps per day, respectively (12). These values are considerably higher than recent estimates for contemporary U.S. adults (13,14) (Fig. 1).


Physical activity, sedentary behavior, and health: paradigm paralysis or paradigm shift?

Katzmarzyk PT - Diabetes (2010)

Average steps per day among Old Order Amish men and women (12) compared with contemporary U.S. adults in the 2005–2006 U.S. NHANES (13) and the 2003 America on the Move Study (14).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2963526&req=5

Figure 1: Average steps per day among Old Order Amish men and women (12) compared with contemporary U.S. adults in the 2005–2006 U.S. NHANES (13) and the 2003 America on the Move Study (14).
Mentions: Modern humans in the Western world have relatively low levels of physical activity compared with contemporary hunter-gatherers. Hayes et al. (9) reported that the total energy expenditure/resting energy expenditure or Physical Activity Level (PAL) among subsistence-level human populations approximates 3.2, while among representative humans living in contemporary society, the PAL is ∼1.67. The impact of the transition from a semi-subsistent existence to a Western lifestyle on physical fitness levels are exemplified by work in an Inuit community (Igloolik, northern Canada) (10,11). Studies in the population from 1970 through 1990 demonstrated marked reductions in average aerobic fitness (ml · kg−1 · min−1) over time in all age-groups (10,11). Recent work among Old Order Amish living a traditional agricultural lifestyle indicates that this population engages in more daily movement than contemporary Americans. The average number of steps per day taken by Amish men and women were 18,425 steps per day and 14,196 steps per day, respectively (12). These values are considerably higher than recent estimates for contemporary U.S. adults (13,14) (Fig. 1).

View Article: PubMed Central - PubMed

Affiliation: Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA. peter.katzmarzyk@pbrc.edu

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

One potential example of this phenomenon could turn out to be the continued focus on moderate and vigorous physical activity as the dominant health-related aspect of human movement... However, if we are complacent with the existing paradigm—that increasing levels of moderate and vigorous levels of physical activity will result in the greatest improvements in public health—then we may not obtain the full return on investment with respect to improving quality of life and life expectancy through patterns of human movement... Emerging evidence for the role of sedentary behavior on health, which may be independent of physical activity per se, finds us at a crossroad with respect to prescribing optimal daily human movement patterns for health... However, the biological, social, and environmental pathways leading to sedentary behavior versus physical activity may be different... Further, the health effects associated with sedentary behavior and physical activity may be the result of different biological mechanisms... A negative consequence to the observed improvements in energetic efficiency is the proliferation of health concerns that are related to low levels of physical activity and/or high levels of sedentary behavior... The results of these three studies are remarkably similar; however, two other studies have shown somewhat different results... An analysis from the ACLS found a significant positive relationship between time spent sitting in a car and CVD mortality in men, but failed to show a relationship between TV viewing and CVD mortality... These postural changes do not reflect many typical sedentary behaviors performed by free-living humans, such as sitting... However, results from the study by Lipman et al., where the investigators immobilized monkeys in an upright position, showed significantly decreased glucose tolerance in immobilized monkeys compared with control animals, suggesting that the effects were caused by the inactivity per se as normal gravitational effects were maintained... For example, removal of intermittent standing and ambulation in rats by hind limb suspension (unloading) results in marked decreases in lipoprotein lipase (LPL) activity (the enzyme responsible for hydrolysis of triglyceride-rich lipoproteins), triglyceride uptake into red skeletal muscle, and reductions in the concentration of HDL cholesterol within a day's time... Importantly, these rapid effects operate through a process that markedly reduces LPL protein and activity without affecting LPL mRNA concentration, whereas both exercise (>twofold increase) and continuous chronic inactivity (>threefold decrease) impact LPL mRNA... The current public health recommendations for moderate and vigorous physical activity are the result of more than 60 years of scientific inquiry that has produced evidence for a causal link between physical activity and health... On the other hand, sedentary behaviors (<100 accelerometer counts per minute) account for ∼55% of an American's typical day... We must begin to explore novel approaches to reduce the widespread exposure to sedentary behaviors, as the potential health benefits to be gained could be substantial.

Show MeSH