1. By Tilly, Lizzie and Tegan

2. The Endorphin hypothesis The Endorphin hypothesis: This is the suggestion that by exercising, our mood states can be improved. However this explanation may relate more to those engaged in more intensive levels of activity. The relationship between physical activity and improved mental health has been widely researched. One key piece of evidence that supports the overall positive effects of exercise is Leith and Taylor 1990 – A review of the psychological aspects of exercise.

3. Aim: Aim: To review a decade of research studies into the effects of exercise on mental health in order to draw out any consistent findings in the context of a critical evaluation of the methodology used in the collection of those data.Methodology:  81 research projects published over a decade.  Used computer search to obtain the studies.  The studies were put in three groups based on Campbell and Stanley’s (1963) system of categorisation. (pre-experimental, quasi-experimental and experimental).  The categorisation was to place each piece of research in the context of its methodology so that the value of its findings were reported in relation to specific mental health.

4. The samples range widely as the studies themselves included;  Students  Alcoholics  Psychiatric patients  Children  Adults  Males  Females  Special education  Classes  Teenagers

5. The researchers further divided pre-experimental research into one-short case-studies, one pre-test/post-test designs and static group comparisons. The first of these categories was not represented as part of the review. 7 of the 9 studies in this category showed significant improvements in the chosen measures of mental health. methodological limitations of these studies were also reported and it was found that only three studies had control groups, which made it difficult to make valid conclusions about causality.

6. 46 studies in this category, nearly all studies had non-equivalent control group, 36 of the studies showed significant improvements in the particular mental health measures used. A wider range of mental health measures were reviewed in this category. It lacked matching between experimental and control groups or absence of random allocation to groups

7.  26 studies were reviewed under this category, 13 of which showed significant improvements.  An additional 5 studies reported partial improvements in various mental health measures.  Design was pre-test/post-test control group. (random allocation)  Least likely to suffer from issues relating to external and internal validity.

8.  70%of studies reported significant improvements in mental health. When the researchers added partial improvements to this figure, it rose to 80%.  However when data was analysed by type design the findings became less convincing.  50% of experimental studies report significant improvements compared to the 78% for the pre-experimental group.  It was also suggested by Leith and Taylor that it would have been important for more studies to measure other variables such as fitness gains, type and duration of exercise as these may have a bearing on the overall effectiveness of exercise.

9. - Reductionist or Holistic? - Determinism or Free Will? - Nature or Nurture? - Ethnocentric? - Ecologically valid? - Valid? - Reliable? - Representative? YOU DECIDE!