Exercise as it relates to Disease/Cardiorespiratory fitness and depression among Middle School Adolescents
This is a critique of the article: Ruggero C, Petrie T, Sheinbein S, Greenleaf C, Martin S. Cardiorespiratory Fitness May Help in Protecting Against Depression Among Middle School Adolescents. Journal of Adolescent Health. 2015;57(1):60-65.
What is the background to this research?
- Depression levels among American middle school adolescents are growing, with a reported 15.9% of females and 7.7% of males with symptoms of depression . Depression has a major negative impact on school performance, with subsequent education and occupational opportunity negatively impacted. Depression symptoms include low self-esteem, impaired ability to concentrate, social withdrawal and decreased sense of worth, which may cause low cognitive performance and a decreased willingness to learn .
- Research into benefits of physical activity and relationship to depression is substantial, whereas cardiorespiratory fitness relationship to depression is scarce.
- Previous studies have only measured physical activity which can change from week to week, whereas measurement of cardiorespiratory fitness allows a long term view of physical activity. This article claims to be the first to assess cardiorespiratory fitness to depression levels from one school year to the next. Thus, measuring a more accurate level of cardiorespiratory fitness, allowing a more in-depth study of how cardiorespiratory fitness and depression levels are related.
Where is the research from?
- The study was conducted in northern Texas, with 197 male and 240 female participants tested in grade six and then grade seven of state-run schools, grade six mean age was 11.55 years.
- All authors of the study bar Shelly Sheinbein (M.S) have a PHD in Psychology or Kinesiology, with previous experience in field-based work and research work. Thus, the authors are experienced and reliable in this field of testing.
- The study was linked to and funded by Northern Texas and Wisconsin University with fitness testing partnered with a state-mandated assessment. Conflict of interest and bias is unlikely due to these universities having no commercial or financial gain from the results of this study.
- This research could be easily replicated in Australian schools, allowing data of cardiorespiratory fitness and depression among Australian middle school adolescents.
What kind of research was this?
- This was a longitudinal cross-sectional study, with participants measured twice over a one-year period. No intervention was implemented. Due to only 2 measurements taken over the year period, this is a weak form of evidence.
- The study relied on both self-reported and fitness data. The self-report data can lend itself to problems with reliability and validity with data accuracy relying on the cognitive bias of students. Fitness data testing is of higher reliability and validity with a set test directly replicated for the measurement.
What did the research involve?
Subjects completed a 20 item self-reported questionnaire using the Centre for Epidemiologic Studies Depression Scale for Children. This created a 0 to 60 depression score scale with questions referring to mood, feeling and sleep patterns. Cardiorespiratory fitness was estimated using three indicators, the first a PACER test, where students completed laps of a set distance in a specific time for each lap with the maximum laps of the test being 100. The other indicators were obtained through a physical self-description questionnaire with questions asking specifically about their endurance, how far they can run without stopping and strength, how strong they thought they were. Scores for the questionnaire ranged from zero to six. Body composition was tested using BMI which was converted into a percentile based on age and gender. Weight was measured by the teacher to the nearest 0.1 lb. The methodology of this study is limited due to the self-report questionnaire bias. As the study relied on the student's self-reported questionnaire, thus, leading to a possible bias to themselves. Students may perceive themselves to have higher/lower endurance or stronger/weaker than they actually are. Self-report bias is well known to be unreliable with the whole study relying on how accurate the student’s self-rate themselves. Cardiorespiratory fitness measurement using the PACER test is a basic measurement indicator, which was easily replicated the following year of testing. Researches completed the testing on exactly the same week of school over both years, providing an exact one-year snapshot with the time of year, season and school load the same over both tests. The use of a longitudinal study created a higher degree of accuracy, with less variability compared to a cross-sectional study, but a limitation of the study is only two measurements over the year.. Other limitations of the study included the self-report bias, a single geographically school district, a study length of only one year, and no random assignment. These limitations lead to a higher number of ethnic group individuals, being Hispanics, with all students tested in a state-run school, thus only testing a certain economic class of students.
What were the basic results?
- The study found that higher cardiorespiratory fitness levels in the sixth grade were associated with significantly less depression by the seventh grade in girls. There was the same association with boys but at a nonsufficient statistical level. In girls’ higher levels of cardiorespiratory fitness were associated with leaner body composition and less depression, with a finding that body composition and cardiorespiratory fitness levels strongly predicting depression levels the following year. The same was found in boys but at a lesser extent.
- I believe there was some over-emphasises in the implications of their findings, due to the self report bias and results only found in girls. The researches did provide all data and conceded the low significant value of the boy’s data. Findings were stated as a small but significant protective effect in girls, which agrees with the data provided by the tests.
What conclusions can we take from this research?
- The study concluded that cardiorespiratory fitness levels were associated with depression levels. I agree with this conclusion but I believe this study can only be used as a guide, due to the unreliability of the self-report questionnaire, selected population group, and with only two testing periods. Cardiorespiratory fitness was shown to be associated with depression levels.
- Further research with a higher, mix of race and social-economic status population groups over a longer period of time would yield a more reliable data set. I believe the conclusion from this study is correct, providing a starting point for further research into this area.
- These findings coincide with other research studies into exercise levels that all found fitness and exercise to have a positively effect on depression levels. Many studies have found a link between physical fitness and improved depression levels, especially evident in female populations  
This research article provides practical advice for the general population, specifically middle school adolescents on cardiorespiratory fitness and the impact on depression levels.
- Increased cardiorespiratory fitness is associated with a positive impact on depression levels and result in a leaner body composition, especially in females. This advice can positively impact school-aged children by promoting a healthier lifestyle, encouraging them to be more physically active and to participate in cardiorespiratory focused activities. These findings have the added benefit of directly correlating to leaner body composition one year later, which can be a high-pressure issue in school-aged children, especially females.
- All readers undertake the ESSA pre-exercise screening tool before any moderate to vigorous exercise is undertaken.
- Middle school adolescents should be getting at least the recommended daily activity level of 60min or more of moderate to vigorous physical activity if cleared by the pre-exercise screening tool. This will support a healthy body and mind relationship, with lower depression levels.
- This research provides a starting point for further research to build on.
These organisations provide advice and support for individuals struggling with depression.
- Black Dog Institue
- Beyond Blue Foundation
- Kids Helpline
- Health Direct Fitness
- The Department of Health fitness guide
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