How Physical Activity Influences Allostatic Load in Midlife: Insights from Finnish Adults

Physical activity is widely recognized as a cornerstone of healthy living. Beyond helping with weight management and cardiovascular health, it plays a crucial role in reducing stress and improving mental well-being. A recent longitudinal study conducted by Korpisaari et al. (2025) sheds light on how changes in physical activity over adulthood affect allostatic load, a measure of cumulative stress, in midlife. Understanding this relationship can help individuals make lifestyle choices that protect long-term health.

Understanding Allostatic Load

Allostatic load refers to the physiological wear and tear that occurs when the body is exposed to chronic stress over time. The concept was introduced by McEwen and Stellar in 1993 and has since become a key framework for understanding the health impacts of stress. Chronic stress can influence multiple biological systems, including the cardiovascular, metabolic, immune, and neuroendocrine systems. Over time, high allostatic load increases the risk of health conditions such as hypertension, type 2 diabetes, obesity, depression, and cardiovascular disease (Suvarna et al., 2020; Guidi et al., 2021).

Clinically, allostatic load is assessed using biomarkers such as blood pressure, heart rate, cholesterol levels, body mass index, waist circumference, glucose, and cortisol. These markers indicate how different physiological systems respond to stress and help quantify the cumulative effects of chronic stress.

Physical Activity and Stress Reduction

Physical activity (PA) is a critical modifiable behavior that can reduce allostatic load. Regular engagement in moderate to vigorous physical activity (MVPA) helps regulate stress hormones, improve cardiovascular function, and lower inflammation. Exercise promotes the activation of the parasympathetic nervous system, which supports relaxation and recovery, and also improves heart rate variability, a key indicator of stress resilience (Soares-Miranda et al., 2014).

In addition to physiological benefits, physical activity has a protective effect on mental health. Studies have shown that regular exercise can reduce symptoms of depression and anxiety, enhance mood, and buffer the effects of chronic stress (Singh et al., 2023; Noetel et al., 2024). By improving both mental and physical resilience, PA reduces the overall burden of stress on the body, lowering allostatic load.

The Study: Linking Changes in Physical Activity to Allostatic Load

Korpisaari et al. (2025) conducted a longitudinal study using data from the Northern Finland Birth Cohort 1966 (NFBC1966). The study included 3,358 adults who had data on leisure-time physical activity (LTPA) at 31 years and 46 years of age. Participants were categorized based on whether they met the World Health Organization’s (WHO) recommendation of at least 150 minutes of MVPA per week. Changes in physical activity were grouped as follows:

1. Stable inactive – participants who did not meet PA recommendations at both 31 and 46 years.
2. Increased – participants who did not meet recommendations at 31 but met them at 46.
3. Decreased – participants who met recommendations at 31 but not at 46.
4. Stable active – participants who met recommendations at both ages.

Two allostatic load indices were calculated at age 46 using biomarkers from cardiovascular, metabolic, immune, and neuroendocrine systems: a 13-item index and a 5-item index.

Key Findings

Stable Inactivity and Increased Risk

The study found that participants who were consistently inactive had a significantly higher allostatic load in midlife. With the 13-item index, the rate ratio (RR) for stable inactive participants was 1.18, indicating an 18 percent higher risk of cumulative stress compared to those who were consistently active. With the 5-item index, the RR was 1.17, showing a similarly elevated risk.

These results highlight that consistent inactivity throughout adulthood substantially increases the physiological burden of stress. Stable inactivity was associated with higher values for blood pressure, waist circumference, body mass index, cholesterol, and cortisol, reflecting the broad impact of chronic stress on the body.

Decreasing Physical Activity is Detrimental

Participants whose physical activity decreased from early adulthood to midlife were also at increased risk of higher allostatic load, particularly when measured using the 13-item index (RR = 1.10). This suggests that a decline in activity levels during adulthood can have significant long-term consequences for physiological stress regulation.

Increasing Activity Offers Protection

Interestingly, participants who increased their activity levels by midlife had allostatic load scores similar to those who were consistently active. This indicates that adopting an active lifestyle later in adulthood can still provide significant benefits in reducing stress accumulation.

Sex Differences

Analyses stratified by sex revealed that stable inactivity and decreasing physical activity were particularly detrimental for women. Females in the decreased group had higher allostatic load, while males showed elevated allostatic load primarily when consistently inactive. These differences may be influenced by biological factors such as hormonal regulation and behavioral factors related to activity patterns.

Mechanisms Linking Physical Activity and Allostatic Load

Several mechanisms explain how physical activity reduces allostatic load:

1. Hormonal Regulation – Regular PA reduces cortisol and other stress hormones, preventing prolonged activation of the hypothalamic-pituitary-adrenal axis (Moyers and Hagger, 2023).
2. Cardiovascular Benefits – Exercise improves heart rate variability and lowers blood pressure, which are key indicators of reduced stress on the cardiovascular system.
3. Metabolic Health – PA helps regulate glucose, cholesterol, and body weight, reducing metabolic risk factors associated with chronic stress.
4. Anti-inflammatory Effects – Regular activity lowers inflammatory markers such as C-reactive protein, which are elevated in chronic stress.
5. Mental Health Support – Exercise promotes neurochemical balance, reduces anxiety and depression, and improves mood, providing a buffer against psychological stress.

Practical Implications

This study provides clear evidence that maintaining regular physical activity throughout adulthood is essential for managing stress and preventing physiological damage. For adults who are inactive, adopting even moderate activity can reduce cumulative stress, supporting better long-term health outcomes.

Some practical recommendations include:

• Aim for at least 150 minutes of moderate to vigorous physical activity per week, as recommended by WHO.
• Incorporate a mix of aerobic activities, such as walking, running, or cycling, and strength training to improve multiple body systems.
• Avoid prolonged periods of inactivity, particularly as life transitions or job demands increase.
• Use activity as a stress management tool, integrating it into daily routines to enhance both mental and physical resilience.
• Monitor other lifestyle factors such as diet, sleep, and alcohol use, which can interact with physical activity to influence allostatic load.

Limitations and Considerations

While the study offers valuable insights, there are limitations to consider. Physical activity was self-reported, which may introduce reporting bias. Only leisure-time physical activity was assessed, leaving out occupational or incidental activity. Allostatic load was measured at a single time point, so changes over time could not be fully captured. The study population consisted of Finnish adults, which may limit generalizability to other ethnic or cultural groups.

Future studies could benefit from objective PA measurements using wearable devices and longitudinal assessment of allostatic load to better understand causal relationships.

Conclusion

The longitudinal study by Korpisaari et al. emphasizes the importance of sustaining physical activity from early adulthood through midlife. Consistent inactivity and decreasing activity levels are associated with higher allostatic load, reflecting the cumulative physiological impact of chronic stress. Conversely, increasing or maintaining activity levels protects against stress accumulation and supports long-term health.

For individuals and public health practitioners, these findings underscore the need to encourage regular physical activity across the lifespan. Adopting an active lifestyle not only benefits cardiovascular and metabolic health but also mitigates the physiological consequences of stress, promoting overall well-being and longevity.

Reference

• Korpisaari, M. et al., 2025. Association of longitudinal changes in physical activity with allostatic load in midlife. Psychoneuroendocrinology, 157, 107725.

Disclaimer: This blog is for informational purposes only and is not a substitute for professional medical advice. Consult a healthcare professional before making changes to your physical activity or health regimen.