Mood, anxiety and depression: the evidence

Can exercise work like an antidepressant?

Exercise can reduce depression symptoms, but it hasn't been shown to work better than antidepressants, and it isn't a replacement for them. Compared with usual care or a placebo tablet, walking or jogging, yoga and strength training each gave moderate improvements in depression¹. Comparisons with medication and talking therapy are indirect, and exercise is best supported as an addition to treatment^2,3. Whatever treatment you have now, keep it up, and tell your doctor or therapist that you're becoming more active.

Can physical activity reduce anxiety, and how?

Physical activity probably eases anxiety, but how much isn't clear yet. Across many reviews, exercise tends to reduce anxiety symptoms³. For diagnosed anxiety disorders the benefit is less certain, so exercise is best treated as something that may help alongside other care². How it works isn't settled either. The body's endocannabinoid system is an emerging idea for less anxiety and better mood, not a proven explanation⁶.

Is exercise an evidence-based treatment for mild to moderate depression?

Yes, for adults with diagnosed depression, exercise is a supported treatment. The NHS says regular exercise can boost mood and is especially useful for less severe depression; any type helps if it suits you and you do enough of it⁷. NICE recommends group exercise as an option for less severe depression, usually more than one session a week with a trained practitioner, for 10 weeks⁷. Strength training showed a large benefit for people with mild to moderate symptoms⁸. Confidence is limited, though: much of the evidence is low quality, and results vary widely between reviews^1,2. Ask your doctor or local services what supervised group sessions exist near you.

How does exercise affect brain chemistry and mood?

How exercise lifts mood isn't settled, and the explanations on offer are still hypotheses¹. Exercise may act through overlapping routes, such as better sleep, less inflammation, confidence, social contact and fitness, but none has been isolated². The endocannabinoid system is an emerging idea for less anxiety and better mood⁶. You don't need to understand the chemistry to benefit: the mood benefit is better supported than any explanation of it. Be cautious about claims that a particular activity will 'boost' endorphins, serotonin or gut bacteria.

What is the runner's high?

The runner's high is a lift in mood and a feeling of euphoria, with less anxiety, after exercise. Endorphins were long given the credit, but that explanation is poorly supported. Endocannabinoids are now the leading idea: their levels tend to rise after a single session of exercise, but reliable proof that they cause the high hasn't been achieved⁴. You don't need to feel a 'high' for activity to be worthwhile. A comfortable pace is enough, so there's no need to push harder to chase one.

Do endorphins really make you happier?

Not in the way the popular idea says. The endorphin explanation was poorly supported, and endorphins released in the body can't easily cross the blood–brain barrier⁴. When endorphin signalling was blocked, people still felt the euphoric, calming effects of exercise, and reported a runner's high at similar rates^6,9. Other factors may play a part, such as sleep, company and a sense of achievement, but none has been isolated². Group-based and supervised programmes showed larger effects on depression than individual activity, so a walking group or class may suit you if you like company³.

How does easing anxiety and low mood through activity improve quality of life?

It isn't clear yet how much easing anxiety or low mood improves quality of life. The clearest benefit is symptom relief in people with diagnosed depression¹⁰. In people with several long-term conditions, quality-of-life gains were smaller with increasing age⁵. In digital programmes for people with long-term conditions, gains in mood, anxiety and quality of life showed at the end of the programme but not at follow-up¹¹. Keep a simple note after sessions of your sleep, energy and mood; it can show you what activity is doing for you. Plan what you'll do once any programme ends.

How do lab findings on exercise and mental health translate to real life?

Benefits seen in trials tend to shrink in everyday life, mainly because fewer people start and keep going. In exercise referral schemes with face-to-face consultations and phone calls, uptake and adherence were 86.8% and 55.3% in trials but 57.9% and 37.2% in routine practice¹². In adults with several long-term conditions, improvements in depression and anxiety seen straight after a programme were not maintained at around 12 months, probably because people stopped exercising regularly⁵. Supervised, group-based and tailored programmes may help you stay with it^3,12. Choose something you can maintain, and look for a programme you can adjust to your pace and health.

Aerobic or resistance training: which helps mental health more?

Neither is clearly better. For depression, aerobic, resistance and mixed exercise all helped, with no clear difference between them¹⁰. For anxiety it isn't clear yet which type helps most, so choose what suits you^10,3. The NHS says any type of exercise is useful if it suits you and you do enough of it, and that you should enjoy it or it may be hard to stay motivated⁷. If you haven't exercised for a while, start gradually and build up towards 150 minutes of moderate-intensity activity a week⁷. Any exercise is better than none.

Does exercise affect the gut–brain axis?

Exercise does appear to change the gut microbiome, but whether that lifts mood is early-stage and not proven. Regular exercise can alter the gut microbiome, often increasing diversity and beneficial bacteria, and these changes are linked with brain function, including mood control¹³. The closest evidence on mood comes from young teenagers with mild depression symptoms, so it may not apply to you, and some of the work is in animals¹⁴. There's no proven 'gut-friendly' way to exercise for your mood; regular, enjoyable activity is a sensible approach. Be wary of claims that you can fix your mood by changing your gut bacteria.

When to check with a health professional

If you're starting exercise after a long break, it's always a good idea to see your doctor first.

Exercise is best seen as an addition to care, not a replacement. If low mood or anxiety is lasting, getting in the way of daily life, or you're finding it hard to cope, talk to your doctor or a mental health service. Don't stop or change medication or therapy without talking to your doctor.

For an injury or a health condition, see a health professional, such as your doctor or a physio. Some muscle soreness when you start is common: ease off, and see a doctor if it persists or gets worse. Exercise shouldn't be assumed to be risk-free for everyone, so build up gradually².

Feeling sick, sweaty or unwell, unexplained discomfort, or breathlessness or dizziness that doesn't settle during or after activity are not things to just ease off for. Use the emergency step below, or see a doctor if it is mild and passing.

Call your local emergency number for chest pain or pressure (or pain spreading to the arm, neck, jaw or back, especially with sweating or feeling sick), severe breathlessness, fainting or collapse, signs of a stroke, a serious injury, or someone who isn't safe. If you have thoughts of self-harm, contact a local crisis line (findahelpline.com lists free services in every country).