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The Stress–Exercise–Health Connection

Stress has been defined as “the rate of wear and tear in the body”. The pace of modern-day living means that many of us lead stressful lifestyles. Whilst not all stress is harmful – indeed we need some degree of stress to stay alert and healthy – the sheer pace and pressures of life can, for many, become intolerable and have a serious effect on mental and physical wellbeing.

Our physiological ‘fight or flight’ responses that were essential for the survival of our primitive ancestors can be unhealthy in modern-day society. Stress and tension have been associated with heart disease, cancer, strokes, infection, asthma attacks, back pain, chronic fatigue, stomach & bowel disorders, headaches, insomnia, immune system depression (leading to more coughs, colds, flu & sore throats)… and the list is still being added to by medical scientists.

When something excites or threatens us, our brain activates the hormonal and nervous systems to handle the situation. The hypothalamus tells the anterior pituitary gland to secrete the hormone ACTH (adrenocorticotropic hormone) which travels to the adrenal gland and orders the release of other hormones called glucocorticoids (e.g. cortisol). These hormones are necessary for the body’s response to stressful situations.

The nervous system activates the release of adrenaline (epinephrine) from the adrenal glands, which mobilise energy stores and increase heart rate and blood pressure. We are ready for action!  However, if we have no physical outlet, these natural stress responses can have a deleterious effect on our health. For example, adrenaline makes the blood clot faster, an advantage in a fight but a disadvantage in the workplace or home where it can cause a heart attack. Glucose and fats are great energy sources when physical action is required but can damage and furr-up the arteries if they left in high quantities in the bloodstream in an up-tight sedentary person.

If you are a ‘hot reactor’ – the sort of person who easily flares up – then this stress response can often be exaggerated. Stress hormones flood out, heart rate and blood pressure soar, glucose and fats pour into the bloodstream and the blood clotting mechanisms are accelerated. If the ‘hot reactor’ is forced to regularly stew in their own juices, this sets the scene for major health problems. Prolonged exposure to stress hormones eventually suppresses the immune system and reduces our resistance to illness.


Around 50 years ago a psychologist called Dr Hans Selye, who pioneered the concept of stress, conducted a fascinating experiment to show the anti-stress benefits of exercise. He subjected 10 rats to a 4-week programme of mild electric shocks, flashing lights and loud noises. At the end of the month all the rats had died due to the stress that this had on their health. He then repeated the experiment and had 10 rats walk on a treadmill until they were in good physical condition, then subjected them to the same stressful programme. At the end of the month, all the rats were alive with no serious affects to their health. Dr Selye concluded that physical fitness helped to ‘buffer’ the health-destroying effects of stress.

Rather more recently a group of 36 physically inactive women were randomly assigned into either a walking or sedentary control group. The walking group exercised at a brisk pace for 45 minutes a day, 5 days a week for 15 weeks. After 6 weeks the walkers not only improved their heart-lung fitness but also improved their psychological wellbeing scores from an average of 70 (indicating a stress problem) to 81 (positive wellbeing) which was maintained throughout the 15-week study. The sedentary controls remained unchanged at around 70. A study of elderly women (average age 73 years) showed psychological wellbeing scores to be significantly higher amongst those who were regular walkers compared to those who were sedentary.


Regular moderate exercise has been consistently shown to minimise the effects of stress. It is relaxing, counters the tendency to form blood clots, uses the blood fats for energy, lowers stress hormone levels, reduces muscle tension and helps blood circulate more freely around the body. Studies have shown that a brisk walk is as effective in reducing stress and tension as a tranquilliser – and more long-lasting.

In general, moderate aerobic physical activity (e.g. walking, cycling, and swimming) seems to be more effective than vigorous, exhaustive activity or resistance exercise in helping reduce stress and tension.

Regular exercise favourably influences the hormones and neurotransmitters associated with depression and feelings of anxiety. Many researchers believe that the feeling of wellbeing that comes during and after exercise is due to mood-altering substances such as serotonin, dopamine, enkephalins and endorphins. There has been a special interest recently in endorphins, a morphine-like compounds released in the brain which can reduce pain, help normalise blood pressure and may induce a feeling of euphoria and wellbeing. It takes around 20 minutes for these endorphins to have an effect, hence the recommendation to take exercise for at least 20-30 minutes on a regular basis.

There’s no doubt that regular exercise makes us feel better and better able to cope with the stresses and strains of daily life. A brisk 20-minute lunchtime walk can work wonders after a stressful morning.



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