Exercise as it relates to Disease/The Relationship Between Physical Activity and Depression in Young Adults
This is an analysis of the journal article 'Physical Activity and Depression in Young Adults' by Charlotte M. McKercher, Michael D. Schmidt, Kristy A. Sanderson, George C. Patton, Terence Dwyer and Alison J. Venn (2009).
What is the background to this research?
Depression is a term that refers to the various psychological distress that ranges from a dysphoric mood state to a diagnosis of a clinical disorder, such as major depressive disorder (MDD).  According to the World Health Organisation (WHO), currently in the world, it’s estimated that over 340 million people are affected by depression.  WHO has also predicted that depression will be one of the main contributors to the global disease burden by 2020.  Even though depression is very common, many people with depression don’t seek treatment, a survey completed showed that only 56.8% of individual’s sought treatment for MDD.  Studies have displayed that increased physical activity improves health concerns such as reducing morbidity and mortality from coronary heart disease, diabetes, obesity, some cancers and also mental health.  Recent research has also focused on the role of physical activity in the prevention and management of depression and depressive symptoms.  The study shown in the journal article ‘Physical Activity and Depression in Young Adults’ aims to further examine the associations between physical activity and depression. 
Where was this research from?
The study was conducted from researches at the following departments of these universities:
- University of Tasmania, Hobart, Australia
- Menzies Research Institute
- University of Melbourne, Melbourne, Australia
- Murdoch Children’s Research Institute
What kind of research was this?
This journal article uses both qualitative and quantitative research.  Qualitative research is used throughout this study by participants completing questionnaires including International Physical Activity Questionnaire (IPAQ) and an interview including Composite International Diagnostic Interview (CIDI).  Quantitative research is used by measuring the participant’s steps using a pedometer and recording the daily steps taken. 
What did the research involve?
The research in this study  involved data that was collected from 1995 non-pregnant participants who participated in the Childhood Determinants of Adult Health Study. Within this study participants were required to complete:
- The International Physical Activity Questionnaire (IPAQ) which assesses the duration of moderate and vigorous intensity leisure, work active commuting and yard/ housework in the past week.
- Participants wore a pedometer for 7 days and kept a pedometer diary which was then used to calculate the average daily steps.
- Participants were also examined for depression for the previous 12 months was assessed using a computerised Composite International Diagnostic Interview (CIDI).
All tests utilised within this study are widely accepted throughout the world. The IPAQ has excellent reliability and reasonable validity. The CIDI also offers high reliability and consistency of administration. The pedometers used in this study are currently the most accurate and reliable pedometers available. But this study included limitations including the cross-sectional design and self-report measures. The use of cross-sectional design has limitations as it’s difficult to make a casual interpretation, it only offers a snapshot of the situation and is considered prevalence-incidence bias.  The use of self-reporting measures are considered to have limitations as self-reporting data can lead to over reporting of physical activity. 
What were the basic results?
The results concluded from this study, that out of the 1995 non-pregnant participants only 1681 (794 males and 887 females) provided valid pedometer data. The results displayed that more steps per day were linked with a lower prevalence of depression. Specifically women that recorded ≥7500 steps per day had 50% lower prevalence of depression when compared to women who were sedentary and recorded <5000 steps per day. Men that recorded ≥12500 steps per day had 50% lower prevalence compared to men who were sedentary.
Using the self- reported data, the results concluded that women who participate in low duration of leisure physical activity for ≥1.25 hours per week were associated with 45% lower prevalence of depression compared to the sedentary group who participate in 0 hours per week. Men who participate in the highest leisure physical activity for ≥3 hours per week had a lower prevalence of depression compared with men who participate in 0 hours per week. Associations between work physical activity, active commuting and yard/house work showed no significant associations in the prevalence of depression.
What conclusions can we take from this research?
The research concluded that individuals who participate in physical activity could potentially improve and manage depression.  There are numerous studies that investigate how physical activity can potentially be a treatment method for depression.  The study conducted in the journal article ‘Physical Activity and Depression in Young Adults’  used reliable and valid methods to verify the associations between physical activity and depression. The findings concluded that when steps per day are ≥7500 in women and ≥12500 in men increase the prevalence of depression. Leisure physical activity in both men and women showed to also increase the prevalence of depression. But work, active commuting and yard/ housework physical activity showed to have no associations in the prevalence of depression.
This research has proven that steps taken per day and hours spend per week doing various types of physical activity can be associated with decreased prevalence of depression. In order for individuals to experience the benefits of this intervention, the participants must be honest in the self-reporting questionnaires and be willing to participate in physical activity.
For further facts, information or support on depression and physical activity, click on the following links:
- McKercher CM, Schmidt MD, Sanderson KA, Patton GC, Dwyer T, Venn AJ. Physical activity and depression in young adults. American journal of preventive medicine. 2009 Feb 28; 36(2):161-4.
- Ehrman J, Gordon P, Visich P, Keteyian S. Clinical exercise physiology. 3rd ed. Champaign, IL: Human Kinetics; 2013.
- Teychenne M, Ball K, Salmon J. Physical activity and likelihood of depression in adults: a review. Preventive medicine. 2008 May 31; 46(5):397-411.
- Ströhle A. Physical activity, exercise, depression and anxiety disorders. Journal of neural transmission. 2009 Jun 1; 116 (6):777.
- Fox KR The influence of physical activity on mental well-being. Public health nutrition. 1999 Mar; 2(3a):411-8.
- McLeod SA. Qualitative vs Quantitative. (2017). Available from: https://www.simplypsychology.org/qualitative-quantitative.html
- Levin KA. Study design III: Cross-sectional studies. Evidence-based dentistry. 2006 Mar 1; 7(1):24.
- Sallis JF, Saelens BE. Assessment of physical activity by self-report: status, limitations, and future directions. Research quarterly for exercise and sport. 2000 Jun 1;71 (sup2):1-4.