By Christian Jarrett

According to statistics published by the British Heart Foundation, we spend 76 days per year, on average, sitting. The World Health Organisation describes physical inactivity as a “global public health problem” that contributes to millions of deaths each year.

You might not be surprised to hear about the harmful health consequences of a sedentary lifestyle, but perhaps less obvious is that physical inactivity is also associated with unwelcome changes in personality over time. Previous research has documented these effects over periods of four and ten years. A new paper in the Journal of Research in Personality has extended this, finding that greater physical inactivity at baseline is associated with deterioration in personality two decades later, even after accounting for any differences in initial personality.

As the researchers, led by Yannick Stephan at Université de Montpellier, point out, there is an upside: the findings suggest that even a moderate increase in your activity levels today could have positive implications for your personality decades from now.

The researchers combined data from three long-running survey studies. Two involved over 6000 participants in Wisconsin, first recruited between 1992 and 1994, aged 53 on average, when they completed a personality questionnaire and answered questions about their physical activity levels. These same participants then repeated the personality questionnaire in 2011. The other study was US-wide and involved over 2500 participants who first took part between 1995 to 1996, aged 46, on average, when they answered questions about their personality and physical activity. The same participants then provided follow-up personality data in 2013-2014. All the studies also recorded extensive information about the participants’ health and any illnesses or psychological problems.

The main take-away is that greater physical inactivity at baseline was associated with sharper declines in conscientiousness, extraversion, agreeableness and openness, as measured two decades later, even after factoring out baseline personality and any differences in health. The pattern also wasn’t moderated by race, age, education or sex.

For a sense of perspective about the size of these links: the associations between physical inactivity and personality change were mostly either as great as, or even greater than, the associations between demographic factors and personality change, and between disease burden and personality change (in a multiple regression on data combined from the three studies, and controlling for other factors like health, the β value for the inactivity and personality correlations was between -.03 and -.06).

These patterns generally held across different intensities of physical activity (the researchers were able to look separately at light physical activity, such as gardening; moderate physical activity, such as brisk walking; and vigorous activity, such as running or lifting weights). However, for extraversion and agreeableness, there was a suggestion that a lack of moderate physical activity might be especially relevant in terms of later declines in these traits.

Although we may not usually think of physical activity as contributing to our personalities, in fact there is a close association between personality and our basic physiology, including our responsiveness to stress. Another part of the reason that lower physical activity may have such long-term links with personality may be due to knock-on consequences of inactivity for our physical capabilities, which will impact the kind of lives we are able to lead. Being less active may also contribute to us becoming less self-disciplined, less curious and adventurous. We will have fewer opportunities for socialising and also miss the mood-enhancing effects of exercise, a detriment that may accumulate over time and potentially contribute to our lower agreeability.

Somewhat unexpected, but consistent with previous research, was the relative lack of an association between inactivity and later higher trait neuroticism (or emotional instability). However there was one exception: lower vigorous physical activity at baseline was associated with higher neuroticism two decades later.

This paper includes a large number of participants and covers an impressive time span. However, it’s far from perfect. It mostly pertains to changes between mid-life and older age. There is also no data on what happened earlier in the participants’ lives – perhaps the participants’ personalities in their youth influenced both their later activity levels and the later trajectories of their trait changes. Genetic differences between the participants could be another major confound, potentially influencing personality trajectories and activity levels. It’s worth noting too that we don’t know how the participants’ activity levels changed over the course of the studies.

Despite these limitations, the findings reinforce the increasingly well-established idea that personality and health are closely interwoven, and that personality is relatively malleable across the life-span.

We already know that being more active is good for our health, this new paper brings home that it’s probably good for our personalities too. Something to ponder when you next decide whether to walk or drive to the shops. “It is likely that the benefits of even a small increase in physical activity may accumulate over time, resulting in significant [positive] personality change,” the researchers said.

—Physical activity and personality development over twenty years: Evidence from three longitudinal samples

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest and is currently writing a book about personality change