Exercise as it relates to Disease/Regular exercise, anxiety, depression and personality

Background Information
The relationship between exercise behavior and mental health has been examined by many researchers (Byrne and Byrne, 1993, Folkins and Sime, 1981, Gauvin and Spence, 1996, North et al., 1990, Salmon, 2000 and Scully et al., 1998). However, population studies on the association between exercise and mental health are scarce. (M.H.M. De Moor et al. 2006)

Both anxiety and depression are known to be correlated with personality, most prominently with neuroticism, but also with extraversion (Costa and McCrae, 1980 and Middeldorp et al., 2005). Because personality traits can index the risk for anxious and depressive psychopathology, they could potentially mediate the co-morbidity between exercise and anxiety and depression.

Personality traits like sensation seeking seem independent of anxiety and depression but predict lifestyle factors such as smoking or drinking (Koopmans, 1997 and Vink et al., 2003) and possibly also exercise behavior.

The Research
This study was conducted by M.H.M. De Moor,, A.L. Beem, J.H. Stubbe, D.I. Boomsma, E.J.C. De Geus in 2006. The aim of this study was to try an analyse a population of subjects and determine whether regular exercise can effect someone's mental health. The specific areas that they were studying were the correlations between exercise, depression and anxiety. The secondary objective for the study was to try and determine if exercise also had an influence on the subjects general personality for example: whether a person is more likely to be introverted or extroverted within society.

Through the use of self-reporting questionnaires being completed every two years, M.H.M. De Moor et al. obtained a sample size of 19,469 subjects that allowed further study the associations between exercise and certain mental health conditions. These self reports were completed between the years of 1991 and finished in 2002.

Along with the major focus points being anxiety and depression, six personality traits were also measure including neuroticism, extraversion and the four dimensions of attention seeking.

Summary of Results
The major results from this research were that the exercising subjects, on average less anxious and depressed (effect sizes from −0.18 to −0.29 SD), less neurotic (effect size −0.14 SD), more extraverted (effect size +0.32 SD), higher in thrill and adventure seeking (effect size +0.47) and higher in dis-inhibition (effect size +0.25 SD) than the non-exercising counterparts (M.H.M. De Moor et al. 2006). Although the differences between exercisers and non- exercisers are considered to be small by other research standards, they are consistent findings throughout both gender and age.

Strikingly, the associations with exercise participation were independent of the well-known main effect of age on exercise prevalence, that is, all associations held for 20-year-olds when exercise prevalence is still 70% but also for 60-year-olds when exercise prevalence has dropped below 30%. (M.H.M. De Moor et al. 2006)

Below are the main results displayed in a graph format. (M.H.M. De Moor et al. 2006)

These graphs display the correlation between exercise, which is displayed in 'METS' on the Y axis, and age in years on the X axis.

Conclusions and Implications of Research
The investigation showed results which could be vital pieces of information for future studies and or prescription for certain mental health disorders. As indicated in the 'summary of results' section, M.H.M. De Moor et al. were able to find certain correlations within their research, linking exercise to particular mental health conditions such as depression and anxiety.

The study was a quantitative analysis of a large population within the Netherlands and all the data was collected via self- reporting questionnaires. The use of self reporting is still controversial as there is a massive amount of research proving the statistics of bias reports and therefore altering the results (Borntrager, C.F.et, al. 2015. pp. 367. Regarding the previous statement, there is no definitive way to assess someones mental status and there are studies which report valid results through the use of self reporting such as Charlotte Clark, et, al.(Vol. 23, Iss. 2,2011) and their research into self reporting in youth and adolescents in South Africa. Charlotte Clark, et, al.(Vol. 23, Iss. 2,2011) stated it was imperative to gather initial data as a benchmark result for each individual, then proceed to re-evaluate each individual at each different stage of the experiment. Through the use of these self reporting questionnaires, M.H.M. De Moor et al. were able to establish this benchmark and with all subjects participating correctly, they should have also attained consistent and reliable data.

The data collected within this experiment was also a twin based study (M.H.M. De Moor et al. 2006). Through analysing the differences in development of twins, the researchers were able to investigate the major differences within the results of each set of twins. This allows for a more thorough association with the desired topic aiming at the correlation between mental illness and exercise. One variation that De Moor et al. selected was to set the exercising participants category as a minimum of working at 4 METS for a minimum of 60 minutes per week. This is to distinguish greater accuracy within the data, determining the quantity and intensity of exercise that was performed and overall, refined the data into results which can be conveyed more effectively. This was a vital component with such a large number of subjects and this variation was a crucial component to attain the most accurate data possible.

Another major flaw within this investigation, which also occurs in all exercise studies is the under-representation of the subjects. Certain subjects may already be very well trained and exercise vigorously consistently or the opposite with subjects who are excessively sedentary and refuse to participate or drop out early (M.H.M. De Moor et al. 2006). This then distorts the results of the population as a whole and makes it difficult to generalize the data, which ultimately leads to invalid results and does not accurately portray the association between exercise and mental health.