Article 1: "Exercise reduces depression and inflammation but intensity matters"
Paolucci, Emily M., et al. “Exercise Reduces Depression and Inflammation but Intensity Matters.” Biological Psychology, vol. 133, 2018, pp. 79–84., doi:10.1016/j.biopsycho.2018.01.015.
Summary:
This article looks at the connection between exercise and depression, but also takes into account the intensity of the exercise being done. The study looked at 3 groups of university students that were split up based on the intensity of exercise that the researcher's wanted them to complete. One group was high intensity interval training (HIIT), the second was moderate continuous training (MCT), and the third was no exercise at all (CON). The groups completed this exercise over a time frame of 6 weeks. The researchers studied symptoms of anxiety and depression throughout the students academic term and also studied their stress levels by measuring the levels of cytokines. They measured three types of cytokines which are pro-inflammatory and their levels generally indicate inflammation levels in the individual. The reason they looked at these was because they were making a link that high levels of inflammation is one of the factors that leads to higher levels of depression.
The results were that for the CON group depression increased and for the MCT group and the HIIT groups depression decreased. However, the stress levels measured by the level of cytokines actually increased for the HIIT group, but decreased for the MCT group. The researchers concluded that this increase in inflammation in the HIIT group might have been due to the heavy intensity of exercise and the high physical stress the body undergoes. They suggest that the best form of exercise to help mitigate the symptoms of depression and help increase mental health in general is moderate-intensity exercise because it decreases the cytokines that lead to inflammation.
Article 2: “Influence of Exercise Intensity for Improving Depressed Mood in Depression: A Dose-Response Study”
Meyer, Jacob D., et al. “Influence of Exercise Intensity for Improving Depressed Mood in Depression: A Dose-Response Study.” Behavior Therapy, vol. 47, no. 4, 2016, pp. 527–537., doi:10.1016/j.beth.2016.04.003.
Summary:
This study is similar to the one above were the goals of the authors were to see what the best dose (or intensity) of exercise was needed to best help with depression. As stated in the article, most people are aware that exercise helps with depression, but not as much is known on the best "dosage" of exercise as a treatment. To go about this, the researchers studied a group of women with Major Depressive Disorder and split them into four groups, 3 of which completed 30 minutes of varying intensity exercise ( one group was intense, one was moderate and one was light) measured by perceived exertion of 11,13 and 15. The fourth group was the control doing "quiet rest on a stationary bike." The mood of the participants was noted pre-exercise and 10 and 30 minutes after exercising.
The results were that depressive mood decreased in the groups that did exercise when measured 10 and 30 minutes after exercise. The intensities that the participants performed at did not seem to have much affect on how much it was lowered. Another thing to note was the the effects of exercise were the same for those taking antidepressants and those not. The researchers concluded from this that any intensity, even if it's light, of acute exercise will help relieve depression at some level and this relief is not limited by the use of antidepressant drugs.
Article 3: "The mental health of Australian elite athletes"
Gulliver, Amelia, et al. “The Mental Health of Australian Elite Athletes.” Journal of Science and Medicine in Sport, vol. 18, no. 3, 2015, pp. 255–261., doi:10.1016/j.jsams.2014.04.006.
Summary:
This article evaluated the mental health of elite athletes and then compared these findings to the mental health rates of the general community to evaluate if elite athletes had higher, lower, or no change in the incidence of mental health. To complete this, the researchers looked at a group of 224 athletes from national organizations about half male and half female and had them complete a self survey asking general demographic questions and then questions relating to mental health status in the individuals. They then compared these results to previously done epidemiological studies that looked at the prevalence of mental health in the community.
The results found that 46% of athletes showed some signs of psychological distress by displaying symptoms of at least one type of mental health issue that was studied. They also found that the other rates of mental health prevalence were very similar to the community rates. Lastly, they found that athletes who were hurt showed higher levels of both anxiety and depression. The researchers concluded that although the appearance of mental health issues in athletes seems similar to the general population, this needs to be taken with caution. The authors argued that there a few factors that could have affected the results such as demographic differences between the two populations and self-reporting and self-selection bias.