The public messaging drawn from international and national health authorities is unequivocal: sitting is bad for health—so reduce it (being a poison), and moderate-to-vigorous physical activity (MVPA) is good for health—so do more of it (being a medicine).1
This “sit less and move more” guidance is tailored to specific populations in terms of age (modified for children and adults of different ages) and current health (modified for people with chronic conditions and living with a disability). However, the guidance is not tailored to the initial levels of physical behaviors across populations.
In this commentary, we are challenging the presumption that less or more of any given physical behavior is always good or bad for health, and thus the correct advice to give. While there is substantial evidence to support that excessive sitting and insufficient MVPA are detrimental to health1—we propose that the health effects of changing one behavior will depend on the current levels of that specific physical behavior. In the following, we will provide examples to illustrate our argument.
For people who sit a lot, sitting may indeed be a “poison” and they should be encouraged to sit less. For example, office workers, who typically spend a lot of time sitting, have been found to improve their health by reducing the amount of time they spend sitting each day.2 However, for people who do not sit a lot, sitting may be their “medicine” and they may need to sit more. For example, retail workers, who typically sit very little during work, may need to sit more to recover from the detrimental health effects of prolonged standing.3
For people doing little MVPA, they should be encouraged to do more MVPA. However, for people who do a lot of MVPA, more MVPA may be a “poison.” For example, elite athletes may need to move less to avoid the detrimental health effects of overtraining (such as overuse injuries).4
So, whether sitting less and doing more MVPA promotes or hinders health may not only depend on the age and health of an individual, but also on their current levels of sitting and moving. The same need to tailor guidance to the current level of physical behaviors could hold for standing and light-intensity physical activity (LIPA). For example, doing more LIPA may promote health for those who do little LIPA (eg, drivers5) but may impair health for those already doing a lot of LIPA (eg, cleaners6).
These examples illustrate that a change to more or less of any physical behavior is not always health promoting or health hindering, but the impact depends on an individual’s initial levels of that behavior. Because the current physical behavior guidelines are only tailored to age and health, acknowledgment of the potential need for tailoring to initial levels of physical behaviors has implications for policy, research, and practice.
Policy: Guidelines need to be developed to suggest what are the “just right”7 levels of physical behaviors so that messages can be tailored to encourage individuals to change their current behaviors toward optimal levels of physical behaviors. For example, the European Agency for Safety and Health at Work has provided guidelines for optimal levels of behaviors—suggesting 60% sitting, 30% standing, and 10% moving during awake time is health promoting.8 Public messages for different populations could be tailored to promote change toward these optimal levels. For example, the messages for nonexercising office workers would be different to the messages for very athletic retail workers (see Figure 1).
—Representation of the sitting and MVPA guidelines and how they apply to some populations but not others. (a) The current WHO guidelines, that is, that adults “should limit the amount of time spent being sedentary” and “should do at least 150 to 300 minutes of moderate-intensity aerobic physical activity, or at least 75 to 150 minutes of vigorous-intensity physical activity, or an equivalent combination” each week (open blue arrows) (approximately 10–45 min/d—blue box)1. (b) The initial levels of sitting and MVPA for a hypothetical nonexercising office worker with initial daily levels of 12 h sitting and 4 min MVPA (brick pattern orange boxes), and that current “sit less and move more” guidance is likely to promote a change that is health promoting (solid green arrows). (c) The initial levels of sitting and MVPA for a hypothetical elite athlete retail sales worker with initial daily levels of 4 h sitting and 180 min MVPA (brick pattern orange boxes), and that the guidance that is likely to be health promoting would be “sit more and move less” (solid green arrows) (Color figure online). MVPA indicates moderate-to-vigorous physical activity; WHO, World Health Organization.
Citation: Journal of Physical Activity and Health 21, 9; 10.1123/jpah.2024-0324
Research: However, we lack adequate evidence for what are the “just right” levels of physical behaviors and how best to support individuals with diverse initial levels of physical behaviors toward “just right” levels. Epidemiological and intervention studies are needed to enable evidence-informed policy and practice.
Practice: Practitioners typically consider the current levels of physical activity behaviors when providing guidance to individuals and groups. Clear acknowledgment of the importance of initial levels of physical behaviors in guidelines and research evidence on optimal levels of physical behaviors will better support the practice of tailoring messages to clients.
In conclusion, only tailoring messaging to the age and health status could be far from optimal for people with very different current levels of physical behaviors. Policy, research, and practice will be enhanced when the potential for physical behaviors to be either health hindering or health promoting is adequately considered.
References
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