Dr Zoe Williams: Physical activity – are we practicing or preaching?
Dr Zoe Williams is a GP working in South London. She is a Clinical Champion of physical activity with both Public Health England and the Royal College of General Practitioners. In addition, she is a director of the British Society of Lifestyle Medicine and founder of the community interest company, Fit4Life. Many may know Dr Williams from her television appearances as a media medic. This talk was given at the Public Health Collaboration conference 2018 at the Royal College of General Practitioners in London.
Dr Williams begins the talk by asking the audience a couple of thought-provoking questions: what are the benefits of physical activity and what we would prescribe it for if it were a drug? Everyone seems in agreement that physical activity provides a range of benefits and could be prescribed for pretty much anything. Dr Williams explains that although it can be difficult for healthcare professionals to have a discussion about physical activity with patients, lifestyle advice is more effective in this area than it is with stopping smoking. Doctors need to advise around 12 inactive patients before one meets the recommended activity levels, while they need to advise around 50-120 smokers before one quits. Dr Williams opines that these figures show it’s worth the time and effort it takes to have this conversation.
Physical activity ranges on a scale from light intensity, through moderate, to vigorous intensity. Anything less than light intensity exercise is considered sedentary. Light intensity activity can be as simple as standing around, as even this engages muscles. Moderate intensity exercise (such as a brisk walk) requires an increase in heart rate, body temperature and breathing rate; however, one should still be able to have a conversation during moderate exercise. Vigorous exercise is intense enough for one to be unable to have a conversation. Dr Williams notes that it is important for people in different states of health to figure out what defines moderate intensity for them by assessing how they feel during the activity. The UK Chief Medical Officers’ guidelines for adults advise 150 minutes of moderate intensity or 75 minutes of vigorous intensity exercise (or a combination of both) per week, broken down into blocks of ten minutes or more. In addition, muscle-strengthening (resistance) activity and balance and co-ordination activity is recommended twice a week.
Currently, around 34% of men and 42% of women in England are not active enough for good health. One study Dr Williams presents found that the UK is less active than many other countries, including the USA, by a large margin. She explains that the UK is following the footsteps of Finland in improving the country’s health by making similar changes to the system.
According to the World Health Organization, physical inactivity is the fourth largest non-communicable disease risk factor in high income countries. Dr Williams opines that healthcare professionals can spend a lot of time focusing on improving the other risk factors such as tobacco use and high blood pressure, but very little time on increasing physical activity. Furthermore, she says that improving physical activity will lead to improvements in the other risk factors as a knock-on effect. Interestingly, Dr Williams explains, much of the benefit of physical activity comes from the first thirty minutes, for people that are doing nothing, so getting somebody that does no physical activity at all doing a little bit is likely to have a very positive effect.
There is evidence that physical activity reduces the mortality and morbidity risk for a wide range of conditions, including type 2 diabetes, Alzheimer’s disease and even some types of cancer. One of the reasons for this, Dr Williams explains, is that physical activity reduces chronic systemic inflammation. It does this through various mechanisms including the release of anti-inflammatory molecules (myokines) from muscle and a reduction in visceral fat.
On the subject of visceral fat, Dr Williams shows some MRI images. Both the images are of obese individuals, but one has a more subcutaneous (under the skin) distribution of fat, while the other has lots of visceral fat including fat in the liver. Dr Williams explains that visceral fat is much more damaging to metabolic health and that BMI is not a good indicator of how much visceral fat someone has. She says she encourages her patients that after increasing physical activity, reductions in visceral fat, and so positive metabolic changes, will be happening even if they are not losing much weight at first.
Moving regularly reduces sedentary behaviour and as Dr Williams explains, there are a number of ways in which sedentary behaviour is bad for us. Firstly, it reduces our metabolism through various mechanisms, including the switching-off of lipoprotein lipase, a fat burning enzyme. Coming back to the concept of systemic inflammation, this is increased with sedentary behaviour as the mitochondria in our cells become more susceptible to damage.
Dr Williams finishes her talk with some clinical tips for healthcare professionals. These are to consider encouraging physical activity in every consultation with the patient’s permission, to follow up these discussions in the future with reviews of progress and goals and to appreciate that the term ‘moderate intensity’ may apply differently to different individuals.