Researchers in the US studying people with chronic diseases found that physical activity may reduce depression and fatigue by increasing self-efficacy, or the belief that one can master physical goals and attain a sense of accomplishment from applying oneself.

These were the findings of a study by lead author Dr Edward McAuley, a professor of kinesiology and community health at the University of Illinois in Champaign, and colleagues, and appears in the journal Psychosomatic Medicine.

A person’s self-efficacy is the belief they can attain a certain goal: an example of my self-efficacy would be that I believe I can climb several flights of stairs or jog around the block without stopping.

While there is lots of evidence that physical activity influences wellbeing, the reason why is less well understood.

McAuley told the media that:

“Physically active individuals have an increased sense of accomplishment, or situation-specific self-confidence, which in turn results in reduced depression and reduced fatigue.”

Many studies have already shown that physical activity reduces depression and fatigue in people struggling with chronic illness; what is new about this study is the suggestion that this may stem from a person’s self efficacy: their sense of mastery over, or belief in his or her ability to achieve, certain physical goals.

“We base our arguments on fatigue being a symptom of depression,” said Edward McAuley.

“Interventions to reduce depression have consistently resulted in reductions in fatigue. The opposite is not always the case,” he added, explaining that previous studies have shown that increasing physical activity also increases self-efficacy, and that this effect is almost immediate.

He said that studies have also shown that changes in people’s self-efficacy affects their levels of depression and fatigue.

McAuley and colleagues decided to explore the extent to which self-efficacy influences the link between increased physical activity and reduced depression and fatigue.

“Our argument was that physically active individuals would have higher self-efficacy, which in turn would result in reduced depression and reduced fatigue,” said McAuley.

For this piece of research they analyzed data from two published studies covering people affected by chronic diseases: one focused on 192 breast cancer survivors and the other focused on 292 people with multiple sclerosis (MS).

Both studies had asked participants to fill in questionnaires but used different measures of health status, physical activity, self-efficacy, depression and fatigue. The second study (the group with MS) also had extra data on physical activity measured from accelerometers that the participants wore during waking hours for seven days. This study also tested all measures again after six months.

Because they were looking not only at how one variable related to another (eg physical activity and fatigue) but also at how an intervening variable (self-efficacy) might affect those variables directly and indirectly, the researchers conducted a cross-sectional path analysis in the case of the breast cancer survivors, and and a longitudinal panel model in the case of the participant with MS, both “within a covariance modeling framework”.

The results showed that:

  • Physical activity had a direct effect on self-efficacy in both groups.

  • In turn, self-efficacy had “both a direct effect on fatigue and an indirect effect through depressive symptomatology in both samples”.

  • However, controlling for the effect of self-efficacy on depression and fatigue led to a significant reduction in the influence of physical activity on both depression and fatigue.

  • Accounting for potential confounders like demographics and health status did not change the statistical significance of these links.

McAuley and colleagues concluded that the findings show:

“Support for at least one set of psychosocial pathways from physical activity to fatigue, an important concern in chronic disease.”

“Subsequent work might replicate such associations in other diseased populations and attempt to determine whether model relations change with physical activity interventions, and the extent to which other known correlates of fatigue, such as impaired sleep and inflammation, can be incorporated into this model,” they added.

McAuley said that the study showed that the effect of physical activity on mastery experiences provides a possible explanation for the relationship between physical activity and reductions in fatigue in breast-cancer survivors and people with MS. “That sense of accomplishment, or situation-specific self-confidence, serves to reduce depression, which in turn reduces fatigue,” he said, adding that increasing self-efficacy also reduces fatigue directly, he said.

McAuley said this meant that programs to increase physical activity should include steps to enhance self-efficacy, which in turn would enhance wellbeing.

“Physical Activity and Fatigue in Breast Cancer and Multiple Sclerosis: Psychosocial Mechanisms.”
Edward McAuley, Siobhan M. White, Laura Q. Rogers, Robert W. Motl, and Kerry S. Courneya.
Psychosom Med Published online in advance of print, November 30, 2009.
DOI: 10.1097/PSY.0b013e3181c68157

Source: University of Illinois.

Written by: Catharine Paddock, PhD