Resolving cause and effect in the association between regular exercise and psychological well-being  

Researchers: Ms Louise Knol and Ms Janine Stubbe

There is a general tendency to assume that the association between exercise and mental health results from a beneficial effect from exercise on psychological well-being. Regular exercisers have lower levels of anxiety, attention, apprehension, depression and fatigue in comparison to non-exercisers. They also have higher self-esteem. However, this association between regular exercise and psychological well-being does not mean that regular exercise causes psychological well-being. Various alternative explanations cannot be excluded. The association could as easily reflect the reverse causality, i.e. emotionally well-adjusted individuals may be more attracted to sports and exercise, and have the necessary energy and self-discipline to maintain an exercise regime. Alternatively, the beneficial psychological make-up of exercises in cross-sectional studies may be based on a common underlying third factor that influences both exercise behaviour and psychological well-being. This third factor may reflect environmental influences like socio-economic status and social support networks or it may be of genetic origin. Finally, the association may be induced in offspring by parental between-traits assortative mating, in which partners with high negative affect “select” sedentary spouses.

Data from the Netherlands Twin Registry (NTR) will be used to investigate the association between regular exercise and psychological well-being. Twins offer a unique opportunity to distinguish between the influences of genes and environment on resemblance of family members. Longitudinal data in two-generational twin families were collected by mailed surveys in 1991, 1993, 1995, 1997, and 2000. Briefly, a range of indicators of anxiety, depression, neuroticism, somatic anxiety and internalising symptoms is available. Exercise behaviour is based on sport participation in leisure time (type, level, frequency, and intensity). A broader assessment of physical activity patterns at work and leisure was also made to estimate weekly energy expenditure. A sixth survey was held in September 2002. Demography, life style, personality and psychopathology, and exercise behaviour have been reassessed. Newly measured items were self-esteem, self-efficacy, self-motivation, and attitudes towards exercise as well as the perceived barriers to exercise and benefits of exercise.

Janine Stubbe has ended the project in 2006.

If you would like to know more about this project, please contact the NTR secretary.