Exercise. The word alone is enough to instil a feeling of dread in a lot of people. I am lucky enough to have gotten into a good exercise routine these last few years, so I don’t mind it. I was introduced to weightlifting from a course at my gym and it’s remained a staple in my exercise routine ever since. Before that, I associated physical activity with repetitive, strenuous cardio that required a lot of effort to get any better at. Lifting weights opened up a different world to me, allowing me to make progress quickly and marvel at how strong I could be. It motivated me to stick to a routine, which is the key part of any exercise regime.
However, recently I haven’t been able to stick to my routine as well as I wanted to. Injuries coupled with the boredom of solo activity are the main reasons for this, so I’ve decided to try and switch it up and try new things. From trying various things – tennis, netball, high intensity exercises – I realised that I missed the feeling of sweating and breathing hard at the gym. Of course, you still sweat when lifting weights, but it’s a different feeling than the continuous grind of cardio. There is something that is cathartic and physically liberating about it – if I’m having a bad day, going for a run makes me feel a lot better.
This led me to look at the evidence of how exercise – both aerobic and anaerobic – benefits mental health. Much of the research looks at trials to improve mental health in people with depression, which is what I will focus on. A recent review by Farris and colleagues in 2019  looked at aerobic and anaerobic exercise interventions for improving mood for people with depression. The main points were that both aerobic and anaerobic exercise interventions produced an antidepressant effect compared to no intervention. It was also found that people in the aerobic interventions were just as likely to stick at it compared to non-exercise interventions such as psychotherapy and antidepressants. However, for anaerobic exercise interventions, there is currently not much research into how well people stick to the intervention. So, it appears as though aerobic and anaerobic exercise are equally as good at alleviating mood, with evidence showing that people stick to aerobic exercise regimes. This does not mean that people are not as good at sticking to anaerobic exercise, rather we don’t have the evidence yet to say for sure either way.
What about the specifics of exercise, such as for how long people exercise for and at what intensity? Longer sessions did not produce a greater antidepressant effect; sessions more than an hour were less effective in alleviating depression. This may be because participants get tired and less motivated with longer sessions which blunts any potential mood improvements. Interestingly, some studies even found that short-term mood relief can be achieved from as little as 5 minutes per day. In terms of the length of the trials, shorter trials (e.g. two months long) were found to have a stronger antidepressant effect than longer trials (e.g. eight months long). This was thought to be due to people getting used to exercise over the weeks and it losing the novelty aspect. Higher intensity training was also better than lower intensity in mood alleviation, but this depended on the mood of the participant; depressed people are less likely to feel good after a hard workout if they weren’t feeling great to begin with.
One thing that stands out to me from this review is how the effectiveness of an intervention largely depends on a person’s preference and their own individual symptoms. Trials that evaluate exercise interventions mainly focus on exercise as having a purely physical effect – which it does – but a person’s attitude towards exercise and whether they are likely to implement it into their routine seems to be down to other contextual factors.
As alluded to in the review, whether an intervention is successful depends on the individuals’ symptoms, with factors such as fatigue and lack of motivation in depression being a barrier to entry in starting an exercise program. A person is unlikely to want to do high intensity exercise if they are already feeling low, even if this has been shown to have a strong antidepressant effect. Negative thoughts about exercise could also blunt mood improvements if a person dreads being active or fears being embarrassed. As mentioned by Farris and colleagues, trials which combine cognitive behavioural skills with exercise programs could address these mental barriers.
But it all counts for nothing if the person doesn’t like the exercise that they are doing, if they are bored of it or feel like it isn’t going anywhere. Study participants are often randomly allocated to exercise groups or control groups. Whilst this is important in showing the effect of the intervention in an unbiased way, if a person is stuck in an aerobic group and they absolutely despise running, it’s unlikely that they are going to get much of it. In a similar vein, these trials often get the participants to do the same exercises over several weeks – 16 weeks of walking or jogging several times a week in the case of Blumenthal and colleagues’ study mentioned in the review . Whilst it is important to establish a routine, this does not have to be monotonous. This may be contributing to why longer trials have a smaller antidepressant effect – perhaps participants are just getting bored of the lack of variation in the exercises that they are doing. Periodically changing the types of interventions could capitalise on the novelty aspect and stronger antidepressant effect of short interventions, whilst encouraging physical activity over the long term.
For something to become part of your routine, you need to like it enough to do it consistently. For people who already have depression, just starting exercise may be the hardest part. But finding something that fits with the person, which has variation and progression, may help build their self-belief. This coupled together with the obvious physical benefits of exercise could be a powerful way of promoting good mental health.
- Farris, S. G., Abrantes, A. M., Uebelacker, L. A., Weinstock, L. M., & Battle, C. L. (2019). Exercise as a Nonpharmacological Treatment for Depression. Psychiatric Annals, 49(1), 6-10. https://doi.org/10.3928/00485713-20181204-01
- Blumenthal, J. A., Babyak, M. A., Moore, K. A., Craighead, W. E., Herman, S., Khatri, P., … & Doraiswamy, P. M. (1999). Effects of exercise training on older patients with major depression. Archives of Internal Medicine, 159(19), 2349-2356. https://doi.org/10.1001/archinte.159.19.2349