Public health importance of light intensity physical activity

Highlights

• •Light intensity physical activity is associated with a marked reduction in chronic disease and mortality risk.
• •That activities of daily living are associated with health benefits supports public health initiatives that advocate for replacing sitting time with standing and engaging in routine activities such as casual walking, leisurely sports and light housework.
• •The shift in focus from movement behaviors in isolation to the integration of all movement behaviors over the whole day will provide movement options for adults, treatment options for practitioners, and greater opportunities for public health promotion.

1. Light intensity physical activity (PA) benefits health

PA guidelines worldwide recommend that adults accumulate 150 min of moderate intensity or 75 min of vigorous intensity PA (moderate-to-vigorous PA (MVPA)) weekly to achieve health benefits.1, 2, 3 Absent from these guidelines are recommendations for light intensity PA (LPA, e.g., walking at a leisurely pace of 3 km/h or less, equivalent to 1.5–2.9 metabolic equivalents). The absence of a recommendation for LPA could lead to the assumption that (a) adults with 0 min of weekly MVPA are completely inactive and (b) LPA is unimportant. This may be discouraging for adults who casually walk their dog, do some gardening, or are routinely active at home or the workplace.

In 2020, the Canadian 24-Hour Movement Guidelines for Adults were the first to acknowledge the substantive health benefits associated with LPA and to provide the recommendation that adults accumulate “several hours of LPA, including standing” daily.⁴ This recommendation was based predominantly on the findings from 2 meta-analyses examining the associations between LPA and all-cause mortality.^5,6 In their meta-analysis of 36,383 men and women with a mean age of 63 years, Ekelund and colleagues⁵ observed that LPA was associated with a substantially reduced risk of mortality in a dose–response manner. Chastin and colleagues⁶ reported that doubling the time spent in LPA was associated with a 29% reduction in mortality.

The evidence demonstrating that LPA is associated with a substantial reduction in mortality risk has recently been marginalized, or even ignored, by authors seeking to demonstrate the importance of PA to reduce cancer risk⁷ and all-cause mortality.⁸ Although the findings of these recent meta-analyses confirm that MVPA is associated with a reduced risk of cancer and all-cause mortality independent of time spent sedentary,⁸ both reports did not consider the potential influence of LPA. This reflects a missed opportunity and one that ignores a large body of evidence demonstrating that LPA is associated with a marked reduction in chronic disease and mortality risk. For example, a meta-analysis of 6 studies (13,960 participants) observed that the risk of cardiovascular mortality was reduced by 20% for each 20-min increase in LPA.⁹ A meta-analysis of 11 studies (49,239 participants) demonstrated that by comparison to participants who engaged in <3 h/day of LPA, all-cause mortality risk was reduced by 29%, 32%, and 44% for participants who engaged in 3–<5 h/day, 5–<7 h/day, and ≥7 h/day of LPA, respectively.¹⁰ This finding reinforces the 24-Hour Movement Guideline observation that progressing toward any of the guideline targets results in some health benefits. In other words, all PA matters, including LPA, and more is better.

The results from a recent meta-analysis of 5 studies (10,151 participants) that considered the association between LPA, MVPA, and cancer mortality made 2 significant observations.¹¹ First, replacing 30 min/day of sedentary time with LPA decreased the risk of cancer mortality by 9%. Second, the reduction in cancer mortality risk for each additional 30 min/day of LPA was not different than the risk reduction for 30 min/day of MVPA (14% vs. 6%). These findings further reinforce the importance of LPA and suggest that for reducing cancer risk, PA duration rather than intensity is most important.

The health benefits of LPA are not restricted to adults. A systematic review examining the relationships between PA and health indicators in school-aged children and youth showed emerging evidence of the importance of LPA in this age group.¹² Recent findings from children aged 11 years followed until age 24 years found that each min/day increase in LPA was associated with a 3.6 g decrease in dual energy X-ray absorptiometry-measured fat mass, far above the 1.3 g decrease observed for each min/day increase in MVPA.¹³ These observations reinforce the health benefits of LPA regardless of age, and for children and youth, underscore the importance of routine lifestyle-embedded PA (e.g., active play), and align with the Canadian 24-Hour Movement Guidelines for Children and Youth.¹⁴

2. Public health implications of promoting LPA

Recognition that the accumulation of any LPA is associated with health benefits supports public health initiatives that advocate for replacing some sitting time with standing and engaging in routine activities of daily living such as casual walking, leisurely sports (e.g., fishing, bowling, billiards) and doing light housework (e.g., cooking, dusting, washing dishes). Indeed, promoting LPA empowers adults who seek options for increasing PA levels, and provides alternatives for practitioners when counselling patients regarding the benefits of engaging in PA.

There is no argument that accumulating ≥150 min/week of MVPA is important. On the contrary, the health benefits associated with MVPA have been established for decades. Rather, we highlight the importance of including the accumulation of daily LPA as a bona fide PA strategy to promote health. This notion is central to the Canadian 24-Hour Movement Guidelines which recognize the health benefits of all intensities of movement, including LPA⁴.

There is little doubt that per minute MVPA produces greater benefits than LPA for most health outcomes for most people. However, many people are unwilling or unable to perform MVPA. Not surprisingly, therefore, MVPA is the least common movement behavior, accounting for <30 min or 2% of the day for the average Canadian adult. Furthermore, any benefit of MVPA is blended with the benefits/harms caused by what a person does in the remaining 23.5 h or 98% of the day. The Canadian 24-Hour Movement Guidelines remind us that “the whole day matters”.⁴ LPA provides almost limitless opportunities for micro-interventions to increase PA through routine daily behaviors in the 16 h/day when the typical Canadian adult is awake but not engaged in MVPA.

3. Conclusion

Adopting and sustaining any PA behavior in today's environment presents very real challenges for most adults. The shift in focus from movement behaviors in isolation to the integration of all movement behaviors over the whole day provides movement options and flexibility for adults, treatment options for practitioners, and greater opportunities for public health promotion.

The global burden of physical inactivity remains a public health challenge. The importance of LPA and MVPA for health emphasizes the importance of promoting PA in all healthcare settings. Tools to assist health practitioners in the promotion of PA are freely available as are public-facing materials that can be posted in any health care setting.^15,16 The message that health benefits can be obtained without engaging in structured, planned MVPA (e.g., exercise) provides achievable options for all adults, addresses individual preferences, and may empower those who seek alternatives for engaging in PA behaviors that mitigate lifestyle-based disease.

Authors’ contributions

RR conceived and drafted the manuscript; IJ and MST critically reviewed and edited the commentary for content and accuracy. All authors have read and approved the final version of the manuscript, and agree with the order of presentation of the authors.

Competing interests

The authors declare that they have no competing interests.