The Not-So-Simple Link Between Stress and Exercise
What is stress?
Stress occurs when our perception of the demands placed on us exceeds our ability to cope. When we are stressed our body activates a ‘fight or flight’ response, and stress hormones such as cortisol and adrenaline are released. This causes an increase in heart rate, breathing rate and blood pressure, so that our body can react to the stressor (i.e. fight it or run away from it).
Stress is not inherently bad. Some stress can be helpful if it’s short-lived, as it can spur us into action to perform a task (e.g. a job interview). However, if our stress response is turned on too often and for too long, this is known as chronic stress and it can be damaging to our physical and mental health (e.g. an unhappy relationship).
Physical symptoms caused by stress can include headaches, stomach aches, chest pain, muscle aches, tiredness, sleeping difficulties and increased susceptibility to illness. Psychological symptoms of stress may include trouble concentrating, feeling overwhelmed, irritability, forgetfulness and loss of libido.
It’s important to note that stress is different for everyone, and what one person finds stressful another person may thrive from (e.g. public speaking). Our perception of stress may be influenced by our genetics, gender, age, personality, socio-economic status, education and coping styles, along with many other variables, and what we find stressful may change across our lifetimes (most of us probably didn’t consider viruses to be particularly stressful this time last year, but now I expect your opinion has changed).
How are stress and exercise related?
The relationship between stress and exercise is an interesting one. I’m sure most of us are aware that exercise can help to reduce stress. This occurs because exercise produces feel-good chemicals in our brains, helps distract us from the stressor and improves our sleep. However, the association between stress and exercise is not always positive. If you’re chronically stressed this can have a negative impact on exercise. This is because exercise is also a stressor and your body cannot tell the difference between physical and mental stressors – it all counts as stress. So if you’re already going through a stressful period of life and you’re putting your body through gruelling workouts on top of that, your overall stress level is going to be very high.
How can stress impair exercise?
1) It reduces motivation to exercise
Research with over 7000 Danish adults found that those who were highly stressed were 2.63 times more likely to be inactive than those who were not highly stressed (Rod et al., 2009). Another study found that older adults with low stress levels were more likely to take part in brisk physical activity three times per week, and were more likely to maintain this for four years than those with high stress (Burton et al., 1999).
2) It increases risk of injury
When you’re stressed you may be distracted so you might not focus on your exercise technique and not perform an exercise safely. Also, your muscles may be more tense than usual and coordination can be impaired (American College of Sports Medicine, 2006). All of these factors can increase injury risk.
3) It excessively increases heart rate
Stress stimulates cortisol and adrenaline production, which increases heart rate and blood pressure. An excessively high heart rate during exercise puts a lot of strain on the body and is associated with an increased risk of cardiac events.
4) It hinders progress
One study found that highly stressed participants did not improve their VO2 max (a measure of aerobic fitness) after two weeks of cycling training, whereas participants with low stress levels did (Kuzma, 2014).
5) It impairs recovery
Research found that students who were highly stressed were more sore, fatigued and low on energy for up to four days after aerobic and resistance training than students with low stress (Stults-Kolehmainen et al., 2014)
6) It increases risk of illness
Chronic stress negatively effects immune function, so you’re more likely to get colds and other illnesses (Segerstrom & Miller, 2004). And if you’re ill you can’t exercise.
What are the signs that stress might be affecting your exercise?
- Your motivation is low
- You lack focus
- You’re tired a lot of the time
- You’re regularly getting injuries or niggles
- You’re regularly getting colds or illnesses
- Your performance has dropped or plateaued
What’s the solution?
My advice is if you’re feeling particularly stressed then stick to lower-intensity forms of exercise, (e.g. walking, yoga, swimming) to calm your mind and avoid putting more stress on your body. It might be tempting to do a sweaty HIIT session to release tension but remember that this might not always be the best thing for your body.
Looking at the bigger picture, if you’re going through a period of high life stress then I’d avoid training for a big sporting event (e.g. a marathon), because this is going to put a lot of stress on your body which is not sensible if you’ve got too much other stress going on. We need to look at stress like a physical injury and be gentle on ourselves whilst we recover from it, rather than wearing ourselves down by adding more stress to our overflowing bucket.
More generally, if you are feeling stressed it’s a good idea to try to use some stress-management strategies to help you to reduce it, e.g. deep breathing, meditation, saying no more often and asking for help. If you’re still struggling, speak to your GP or a therapist who can provide further support.
American College of Sports Medicine, American Academy of Family Physicians, American Academy of Orthopaedic Surgeons, American Medical Society for Sports Medicine, American Orthopaedic Society for Sports Medicine, & American Osteopathic Academy of Sports Medicine (2006). Psychological issues related to injury in athletes and the team physician: a consensus statement. Medicine and science in sports and exercise, 38(11), 2030–2034. https://doi.org/10.1249/mss.0b013e31802b37a6
Burton, L.C., Shapiro, S., & German, P.S. (1999). Determinants of physical activity initiation and maintenance among community-dwelling older persons. Preventative Medicine, 29(5), 422–30. [PubMed: 10564634]
Kuzma, C. (2014, February 9). 5 surprising ways stress messes with your workout. Shape. https://www.shape.com/lifestyle/mind-and-body/5-surprising-ways-stress-affects-your-workout
Rod, N.H., Gronbaek, M., Schnohr, P., et al. (2009). Perceived stress as a risk factor for changes in health behaviour and cardiac risk profile: a longitudinal study. Journal of International Medicine, 266(5), 467–75. [PubMed: 19570055]
Sapolsky, R. M. (1994). Why zebras don't get ulcers: A guide to stress, stress related diseases, and coping. New York: W.H. Freeman.
Segerstrom, S. C., & Miller, G. E. (2004). Psychological stress and the human immune system: a meta-analytic study of 30 years of inquiry. Psychological bulletin, 130(4), 601–630. https://doi.org/10.1037/0033-2909.130.4.601
Stults-Kolehmainen, M.A., Bartholomew, J.B., & Sinha, R. (2014). Chronic psychological stress impairs recovery of muscular function and somatic sensations over a 96-hour period. Journal of Strength and Conditioning Research, 28(7), 2007-17. doi: 10.1519/JSC.0000000000000335. PMID: 24343323.