Exercise and Mental Health: What’s Optimal?

Older Adult Exercising on Treadmill As the winter months ensue, health behaviors are at risk for taking a negative turn due to changes in eating patterns with more exposure to calorie-dense holiday foods, increased sedentary time, reduced overall activity, and altered sleep patterns.  In addition, reduced exposure to natural light, as people tend to stay indoors due to inclement weather, may contribute to altered mood, “feeling blue” and increased depressive symptoms. Cardiovascular nurses have long appreciated the importance of physical activity, especially during winter months, for its effects on reducing risk factors, managing weight during this time of potential weight gain, and reducing the risk of cardiovascular disease and stroke. However, associations between exercise and mental health have not been as clearly defined, with past studies reporting conflicting results likely due to variations in how exercise was defined and small sample sizes.  An interesting study reported in 2018 sheds some important light on this topic by examining the associations between mental health and the exercise type, frequency, duration and intensity.1

The researchers accessed a large data set from the Centers for Disease Control and Prevention Behavioral Risk Factor Surveillance System (BRFSS). This survey is conducted each year, asking a variety of questions of respondents about their health and behavior. The sample of adults greater than 18 years in age was large (N=1,237,194) and diverse. Information on exercise type, duration, frequency, and intensity was used to divide the sample into those who exercised and those who did not, and the groups were well balanced (matched) on a variety of physical and sociodemographic variables, including age, race, gender, marital status, income, education, body mass index, self-reported physical health and prior diagnosis of depression. The exercise and non-exercise groups were compared on the number of bad mental health days experienced in the last month, reported in response to a standardized BRFSS question: “Now thinking about your mental health, which includes stress, depression, and problems with emotions, for how many days during the past 30 days was your mental health not good?”1  The analysis was by regression with adjusting for the covariates noted above.

Mean poor mental health days was 3.36, and findings revealed that the people who exercised had 43.2% fewer days of poor mental health than those who did not. This was actually only 1.49 fewer days, but importantly, within the exercise group, all types of exercise were associated with better mental health over not exercising. Team sports, cycling, and aerobic and gym activity were the most associated accounting for 22.3%, 21.6% and 20.1% lower mental health burden, respectively. The authors suggested that there may be a social component of these activities that was additive.1 An exploratory analysis revealed that even “mindful” types of exercise such as yoga or Tai Chi were better than not exercising.

Several non-linear associations were found indicating U shaped patterns – less relationship at the lower and higher ends of the data. This was seen in dose of exercise and response, and the most associated time was 30 to 60 minutes (most optimal around 45 minutes) for all types of exercise.  However, duration of an episode of exercise of 90 minutes to 3 hours was associated with worse mental health. Optimal frequency was 3-5 times a week, with lower mental health in those exercising less frequently and in those exercising more than 5 times a week.  The worst outcomes were for those who exercised greater than 23 days per month or for durations of greater than 90 minutes.1 If a prior diagnosis of depression was reported, the positive influence of exercise was even greater. The associations of exercise and mental health held across all age, gender, racial, and household income groups.

Although this study was cross-sectional, and interpretation of one-way cause-effect is cautioned, the strengths of the large and diverse sample as well as the robust analysis provide confidence in the associations of exercise and mental health or reduction in self-reported poor mental health days in the context of exercise. Important evidence is provided for cardiovascular nurses who can incorporate these findings in their patient education and counseling, especially by encouraging patients and those at risk to engage in exercise to reduce low mental health days. Specific recommendations could include types of exercise most beneficial, such as team sports and cycling when appropriate, and individualized counseling regarding type, frequency, and duration of exercise according to what the person might be able to do in the winter months. Most important, cardiovascular nurses can encourage and motivate patients by explaining that any exercise is helpful for their mental health over none at all.  
  1. Sammi R Chekroud, Ralitza Gueorguieva, Amanda B Zheutlin, Martin Paulus, Harlan M Krumholz, John H Krystal, Adam M Chekroud Association between physical exercise and mental health in 1·2 million individuals in the USA between 2011 and 2015: a cross-sectional study. Lancet Psychiatry 2018; 5:739–46.