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Source: Ditty_about_summer/Shutterstock

Everybody knows that you should "eat healthier, sit less, and exercise more" to maintain well-being across your lifespan. But just how much exercise—in terms of duration and aerobic intensity—is necessary to trigger the benefits of physical activity as we age?

Until now, the answer to this question has eluded experts and been a source of fierce debate. But there is some good news: A recent randomized clinical trial from Tufts University has partially answered the million-dollar “dose response” question of how much physical activity is necessary to reduce older adults’ risk of immobility and disability. These findings were published August 18 in the journal PLOS ONE.

48 Minutes of Moderate Physical Activity Per Week Is a Tipping Point 

The new Tufts-based study found that inactive older adults who add just 48 minutes of moderate physical activity per week (in the form of walking-based exercises) significantly lowered their risk for major mobility disability. Additionally, anything above 48 minutes of moderate exercise per week was a tipping point associated with improvements in overall physical functioning when compared to adults who were sedentary.

Jean Mayer of Tufts University was the lead author of this study along with about a dozen collaborators from other institutions including the University of Maryland, Stanford University, the University of Florida, Northwestern University, UMass Amherst, the University of Pittsburgh, Wake Forest University, and Southern Connecticut State University. 

For this pioneering study, the multi-disciplinary team of researchers set out to ascertain how various doses of physical activity impacted 1,635 men and women aged 70-89 who were participating in the ongoing Lifestyle Interventions and Independence for Elders (LIFE) study over the course of 2.6 years. The researchers were pleasantly surprised that 48 minutes of exercise was enough to reap benefits. 

The authors summarize the main takeaway of this study in their conclusion: "The dose of change in physical activity associated with the greatest benefit was greater than 48 minutes per week of physical activity. These data support that beneficial effects of physical activity can be realized with substantially less physical activity than is currently recommended for most inactive older adults."

In a statement Roger A. Fielding, senior scientist and director of the Nutrition, Exercise Physiology, and Sarcopenia Laboratory at the USDA HNRCA, said: "Our goal was to have participants walking up to 150 minutes per week. To see benefits at 48 minutes is encouraging. We wanted the physical activity sessions to include exercise that participants could do outside of the study, and we hope that learning of these results might motivate others to try to make safe, incremental changes to their activity levels. Reducing muscle loss, functional decline and loss of independence are important to anyone, at any age, and at any physical ability."

The Bottom Line: Any Amount of Physical Activity Is Better Than Nothing

In a perfect world, we'd all have the time, motivation, and physical wherewithal to perform at least 30 minutes of moderate-to-vigorous physical activity (MVPA) most days of the week as adults ages 18 to 64. That said, these recommended guidelines often backfire because countless people view 150 minutes of exercise per week as overwhelming or unsustainable for a variety of reasons.

Therefore, it's imperative to drive home the message that there is a growing amount of empirical evidence showing that small amounts of physical activity can reap huge benefits across your lifespan. 

For example, a 2015 study, ”Low-Dose Physical Activity Reduces Mortality in the Elderly. A Systematic Review and Meta-Analysis,” led by David Hupin from the Department of Clinical and Exercise Physiology at the University Hospital of St-Etienne-Lyon in France concluded that just 15 minutes of "light" activity (including housework) per day could improve sedentary older adults' health and longevity. 

The French study of more than 1,000 elderly subjects found a negative correlation between a person's level of physical activity and his or her risk of "all-cause" death. In this paper, Hupin et al. emphasize that physical activity reduces mortality rates in a "dose-dependent" way. Yes, more physical activity is more beneficial up to a certain point. However, even very low levels of cardiorespiratory intensity and exercise duration have huge benefits. 

Hupin is optimistic that shifting the focus to lower-dose recommendations of physical activity will inspire anyone who views exercise as a disagreeable experience or inconvenience to make "microdoses" of physical activity a part of his or her daily routine.

The French researchers have been encouraging public health advocates around the globe to revise their recommendations for the quantity and intensity of exercise that is necessary to reap health benefits from physical activity as we age. Hupin said, "This message should be relayed by general practitioners, who play a key and essential role in promoting exercise behavior in the elderly. Even a little is good, and more may be better."

The latest research findings by Jean Mayer and colleagues corroborate Hupin's message and give us very specific new guidelines: 48 minutes per week of physical activity can make a transformative difference in the lives of older adults. 

References

Fielding, Roger A., Jack M. Guralnik, Abby C. King, Marco Pahor, Mary M. McDermott, Catrine Tudor-Locke, Todd M. Manini et al. "Dose of physical activity, physical functioning and disability risk in mobility-limited older adults: Results from the LIFE study randomized trial." PloS One 12, no. 8 (2017): e0182155. DOI: 10.1371/journal.pone.0182155

Hupin, David, Frédéric Roche, Vincent Gremeaux, Jean-Claude Chatard, Mathieu Oriol, Jean-Michel Gaspoz, Jean-Claude Barthélémy, and Pascal Edouard. "Even a low-dose of moderate-to-vigorous physical activity reduces mortality by 22% in adults aged ≥ 60 years: a systematic review and meta-analysis." Br J Sports Med (2015): bjsports-2014. DOI: 10.1136/bjsports-2014-094306

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