In the UK every week (and the US is similar) one in six adults experiences symptoms of a common mental health problem, such as anxiety or depression. Nearly half of adults believe that, in their lifetime, they have had a diagnosable mental health problem (1). In a recent survey of 2,000 workers across the UK, from junior level through to managing directors, nearly a quarter think their organisation does not take employee wellbeing seriously and more than half work for companies which do not offer health benefits such as counselling, health screening and subsidised gym memberships – with two in five have taken time off work or reduced their responsibilities because of their health (2)
Exercise as an mental health intervention
Aerobic exercise can be an effective self-help intervention for mental health episode management and building resilience longer term. Numerous studies have revealed the beneficial effects of regular exercise across a variety of mental health measures and outcomes – including increased cognition, mood, and general quality of life (review).
But what about strength (resistance) training? Aside from building muscle mass, bone density, and endurance, can this kind of exercise help with the neurobiological systems involved in mental health?
What is strength / resistance training?
This kind of training builds muscular strength and endurance by exercising a muscle or muscle group against external resistance. Free weights, weight machines, resistance bands, medicine balls, or the weight of your own body can be used in this way. A simple body-weight example is the 7 minute workout.
There have been two main reviews of clinical trials looking at the effect of strength training on mental health, and both conclude that it can be an effective intervention, particularly at low to moderate intensity – with the resistance (weight) say 50% of the maximum you can lift or pull in a single repetition – done for multiple repetitions.
In O’Connor and colleagues’ 2010 review, improvements in cognition, increases in self-esteem, and decreases in depression were noted across several randomized clinical trials.
Managing anxiety episodes
Can we use something like a 7 minute workout to help reduce symptoms of a current bout of anxiety we may be experiencing? The research tells us we can.
Strickland and Smith’s 2014 review found that even a single session of strength training can reduce the state of anxiety. The intensity of the training mattered. When exercise intensity is reduced to 40–55% of a one-repetition maximum weight, immediate decreases in anxiety have been consistently reported, and such anti-anxiety (anxiolytic) effects have been demonstrated at intensities as low as 10% of 1-rep maximum.
Example low to moderate strength training workout
A modification of the ‘7 minute workout’ is a good example of a strength / resistance workout that meets the criteria. There are 12 exercises. Exercises are performed for 30 seconds. Rest intervals should be longer than in the original high intensity interval training version of this workout (see below).
Rest intervals may also play an important role in the anxiety-reducing effects of this kind of resistance exercise. One study found that exercise performed at low intensities with long rests between sets (one and a half minutes) produced robust decreases in state anxiety relative to high intensities with short rests (half a minute).
For this reason we do not recommend High Intensity Interval Training workouts (HIITs) for anxiety episode management.
It is also worth noting that the majority of findings suggest that females may be more sensitive to the anxiety-reducing effects of strength exercise than males.
Reducing anxiety and improving wellbeing long-term
Just as with single-sessions outcomes, the positive effects of resistance / strength training on anxiety for regular workouts of 6 weeks or more depend on exercise intensity, with the best effects observed at low-to-moderate intensities (e.g. 50% max lifting weight).
Aerobic and strength training synergy
In a 2012 study on women with generalized anxiety disorder (GAD), there were robust decreases in anxiety when strength training was combined with aerobic exercise, which alone failed to decrease anxiety symptoms.. This synergy effect suggests that strength workouts may enhance the known effects of aerobic exercise.
Why strength training can help anxiety
There are a number of possible mechanisms that can explain why strength training can help with our mental health.
1. HPA axis function
Anxiety often occurs with unexpected or extended activation of the stress response along this hypothalamic-pituitary-adrenal (HPA axis), resulting in hypervigilance, fear, and degregulation of the sympathetic nervous system.
Through modulation of cortisol activity, resistance / strength exercise may affect anxiety at via this HPA axis.
Unlike aerobic exercise which is known to increase BDNF and some neurotransmitters, little is known about other central nervous system changes resulting from strength / resistance training and how these might affect anxiety and general mental health.
2. Improving sleep
Disturbed sleep often goes hand in hand with anxiety disorders.
In one 2015 study, young women with generalized anxiety disorder (GAD) were randomly assigned to lower-body weight training (resistance / strength exercise), cycling (aerobic exercise), or a waiting list (the control group). The resistance and aerobic exercise groups each worked out twice a week for six weeks.
The results? Both types of exercise improved sleep – and strength training was particularly helpful.
3. Keeping anxiety from escalating
A third way in which strength workouts may help anxiety is by reducing what is called anxiety sensitivity. This is the fear of the physical sensations caused by anxiety. People who are high in anxiety sensitivity might believe that a racing heart is a sign of an impending heart attack, which only makes them feel more alarmed, making symptoms even worse. After a while, they begin to fear not only the situation that set off their anxiety, but also the distressing sensation itself.
In another 2015 study, people were randomly assigned to a single, 20-minute session of weight training (strength / resistance workout), treadmill use (aerobic exercise), or rest (the control group). Afterward, they took part in a carbon dioxide challenge task. This involved inhaling a whiff of carbon dioxide mixed with oxygen, which made them feel like they were short of breath which is like the rapid shallow breathing that often goes with an episode of anxiety. The results showed that resistance exercise and aerobic exercise were equally effective at reducing anxiety sensitivity.
The cumulative evidence to date indicates that strength training may be an effective way to reduce anxiety and other negative mood states – both in managing episodes of intense anxiety, as well as in reducing long term susceptibility to being anxious and over-stressed.