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People may take up or drop exercise habits during the life course, but these long-term patterns of activity may be associated with different risks of early death.
Data from the Australian Bureau of Statistics (ABS) National Health Survey showed that almost 4 in 10 Australian adults aged 18-64 weren’t getting enough physical activity in 2022. The proportion of people who were insufficiently physically active increased with age, from 34% of those aged 18-24 to 42% of those aged 55-64. Physical inactivity has also become a global health challenge, with the cost of inaction reaching approximately $47.6 billion per year. In Australia, considerable health costs have been reported in mid-aged adults being long-term inactive, which can be 30-40% higher than those with sustained activity. Previous research suggests that being inactive or not meeting physical activity guidelines is associated with a higher risk of death compared with those who are more active; however, relevant research usually measured people’s activity levels at a single time point. Since people’s physical activity habits can be influenced by life transitions and events, single-time-point measurements may lead to less accurate prediction of future health outcomes.
Therefore, this study explored the question: how did the risk of death vary when we consider people’s physical activity in the long term, instead of just at one point?
This study
We summarised evidence from 85 previous studies that looked at how long-term physical activity was associated with the risk of death from all causes, cardiovascular disease, and cancer. Together, these studies included data from approximately 7 million adults worldwide. We found that physical activity in the long term might be more important than we previously believed. People who stayed consistently active had around a 30-40% lower risk of death from any cause, while those who increased their activity over time had 20-25% lower risk. However, people who became inactive had much smaller health benefits than those who stayed active or became active. Similar patterns were shown for cardiovascular deaths, while the results for cancer deaths were less consistent. Evidence from studies on accumulated activity or the average effect of fluctuating activity was less robust, largely due to their limited numbers in previous research.
Another important finding was that for people who were either consistently active or who became active over time, the biggest drop in risk occurred at activity levels below the World Health Organization (WHO) guidelines (ie, 150-300 mins moderate-to-vigorous activity per week). But activity levels above the recommendation offered only limited extra benefit, especially for those increasing their activity over time. In addition, people who became inactive might still show reduction in death risk compared to those who were always inactive, but this could depend on how active they were before, and more research is needed on this.
This is the first and currently largest review to summarise the associations between long-term physical activity and the risk of death from all causes, cardiovascular disease, and cancer in large populations. However, there are also limitations such as less robust results for cancer-related deaths, weak evidence from device-measured physical activity, and the lack of exploration on occupational activity. More detailed discussions of strengths and limitations are available in the original publication.
Implications on public health and research
This research gained broad public interest, which was earlier featured in CNN, 7News Brisbane, etc. The messages from public such as “I didn’t realise that even starting to exercise at an older age could lead to such noticeable health improvements” underscores the need to emphasise the importance of long-term physical activity across Australian communities and health services.
Although previous studies have reported the benefits of physical activity on various health outcomes, most of their results are based on single-time-point measurements. In our research, the influence of changes in physical activity were specifically examined, and our findings suggest substantial health benefits for people being and becoming active over the long term. Moreover, our research reveals that future public health efforts should not only target people who are inactive or insufficiently active but also focus on encouraging those who are already active to maintain their activity levels. In addition, this study supports the idea that it’s never too late to start, and it’s never too little to make a difference. Older adults can still gain health benefits from being or becoming active, and people do not necessarily need to meet the activity guidelines to achieve the benefits of physical activity. Even a small activity habit (eg, taking the stairs instead of the lift, or walking short trips instead of driving) can still count towards health gains, especially for those living a sedentary lifestyle.
This review found only two Australian studies on long-term physical activity and mortality, while most of others come from Europe or the United States. Given the cultural and social differences in how people perform physical activity in different countries, more research is needed in Australia to explore questions like: Is there a “minimum dose” of activity to be accumulated to achieve health benefits? Do periods of inactivity “wash out” the gains from earlier activity? Is there an optimal timeframe for maximising the benefits? Answers to these questions may guide more effective public health interventions for Australian communities.
Conclusion
We believe that a deeper understanding of long-term physical activity could be the key to reducing the burden of physical inactivity and related diseases in Australia. Such knowledge may help more Australians to start or maintain their exercise habits for better health.
Ruyi Yu is a PhD candidate at the School of Public Health, the University of Queensland (UQ).
Dr Gregore Mielke is a Senior Lecturer and NHMRC Emerging Leadership Fellow at the School of Public Health, the University of Queensland (UQ).
The statements or opinions expressed in this article reflect the views of the authors and do not necessarily represent the official policy of the AMA, the MJA or InSight+ unless so stated.
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