Chapter 39
Loving Our Muscles for Life — Part 1
One of the greatest fears that people express regarding getting older is of developing dementia. There is an emerging consensus that exercise in midlife prevents or delays dementia in later life. Some studies suggest that the effect is as large as a reduction of 30 per cent – in other words, people who exercise regularly are less likely by a third to get dementia. However, as yet, this is difficult to prove definitively because so many other elements linked to dementia are also influenced by exercise, such as weight, blood pressure, education, occupation and diabetes. Most of the studies that have looked at the relationship between exercise and dementia have either looked back over the amount of regular exercise that someone did throughout their life and so were dependent on a person’s ability to accurately recall this or started to study people in their forties and fifties and followed them thereafter. The latter are the best type of studies to really address the question properly but clearly are long term and most are still in progress. Mice are a good model to study the link between exercise and dementia and provide a faster conclusion. A mouse lives for two to three years. As part of a research study, mice had genes modified so that they were more likely to get dementia. In these mice, exercise protected against developing dementia and BDNF was key to this prevention. With an accumulating wealth of data on the benefits of physical activity on brain function, clinicians have begun to prescribe exercise to patients with brain diseases such as Parkinson’s and Alzheimer’s as well as other brain disorders, from epilepsy to anxiety. Many clinical trials of exercise interventions for age-related brain disorders are underway. Promising results could further bolster the use of exercise as a neurotherapy. You will recall that we discussed the importance of inflammation in the ageing of cells and how low or no background inflammation slows down ageing and higher background inflammation accelerates ageing. Exercise isn’t just good for the heart, blood vessels and brain. Because it lowers background inflammatory states in the body, it leads to a reduction in all of the conditions that become so much more common as we get older and are linked to inflammation. These include arthritis, cancer, diabetes and strokes. I’ll pause to explain inflammation and accelerated ageing in this context. If we get an infection, we mount an inflammatory response that ‘eats up’ the infecting agent. This is good and it’s what we want to happen. Once it has dealt with the infection, the inflammatory response recedes. However, if the inflammatory response continues to be active in the background, this is bad for cells and causes release of toxic proteins, which in turn further increase inflammation.
Chapter 11: Loving Our Muscles for Life
So we only want inflammation when we have an infection or other insult to the body, otherwise it should be asleep in bed and not troubling our systems. Background inflammation is closely linked to body fat. Fat cells produce toxic proteins which trigger inflammation. The fat that is most likely to produce these toxic proteins is the white fat that settles on our bellies and around our internal organs – this is why a big belly is bad news. Muscle mass declines and fat mass increases as we age, and these toxic proteins consequently increase and cause chronic low-grade inflammation. Regular physical activity decreases fat, including the fat most likely to produce pro-inflammatory conditions. Fat cells also make the immune response less efficient. We saw this with Covid-19, where obesity was one of the principal risk factors for suffering from severe consequences, including death. This is dramatically illustrated by a recent French study in which the need for mechanical ventilation in the ICU in patients with Covid-19 was seven times higher for those who were obese (with body mass index (BMI) greater than 35 kg/m) compared with those with a lower BMI (greater than 25 kg/m). Two of my clinical colleagues who have been overweight or obese for as long as I have known them recognised this association very early on in the pandemic and I quite literally did not recognise them when we met for the first time after a number of months – they had deliberately lost so much weight. Currently, understanding how to improve defences against infections is a global priority. Both viral and bacterial chest infections are less frequent in people who take regular exercise because physical activity boosts the immune system and causes the regularisation of the inflammatory responses. Physical activity makes a difference to these defences. Exercising muscle also releases enzymes called myokines that transiently block harmful inflammatory proteins and promote release of other proteins which are anti-inflammatory, providing another potent counter-attack to the chronic background inflammation that can characterise ageing. Many people think that its ‘too late to start exercising’ or ‘I’ve missed the boat’ – not so. Introduction of exercise at any age changes immune responses for the better. There is strong evidence to support the fact that it is never too late to start or to increase exercise. Many studies of exercise performed one to six times per week over a period ranging from six weeks up to ten months have shown multiple positive effects on the immune system and inflammation, even in old age. One common cause of debilitating winter infections is influenza, the ‘flu’. Influenza is a viral infection that attacks the respiratory system, the nose, throat and lungs. People over 65 are more prone not only to influenza but also to severe side effects from influenza.
Chapter 11: Loving Our Muscles for Life
It is heartening to know that exercise can improve not only the body’s response to flu but also responsiveness to the flu vaccine. Vaccination is recommended for all people over 60, in addition to healthcare workers of all ages and anyone who is vulnerable because of co-existent diseases. Unfortunately, the vaccine is not at all as effective in older ages as in young adults: it works in 90 per cent of young adults but only 50 per cent of people over 65. Anything that can improve this response is important and exercise helps to do just that. In one elegant study, doing aerobic exercise for the three months before having the flu vaccine significantly improved vaccination responsiveness in particular. Despite the fact that regular physical activity is associated with these major health benefits, ageing is accompanied by a sharp decline in both duration and intensity of physical activity and the majority of adults fail to meet the World Health Organization (WHO) recommended guidelines of 150 minutes of aerobic exercise per week. The figures in Ireland and the UK are frankly shameful: almost two thirds of persons 50 years of age and over fail to meet the recommended criteria. In a large British study, adults aged 40 and older reported spending more time on the toilet each week than walking – an average of 3 hours and 9 minutes on the toilet, compared with 1 hour and 30 minutes of walking. You may well wonder who was conducting the timing for that striking study! Furthermore, just one in ten UK adults were aware of the periods of time recommended for physical activity. Work is the biggest barrier to being more active, with 20 per cent of people citing ‘being too busy with work’ as a reason for not exercising. Yet productivity is better after exercise. Another pertinent problem is that two thirds of us spend at least six hours each day sitting, a factor which also significantly increases the risk of an early death. Charles Eugster, a retired dentist, delivered an inspirational TED talk on exercise and ageing at the age of 95. He described how he had started bodybuilding when he was 87 years old.’ His story up to then was a familiar one. In youth, he had been a champion sprinter but he grew less and less active as he aged. The athletic glories of his youth gave way to sedentary married life. Summer days rowing and boxing slowly transitioned into evenings in front of the telly – a familiar narrative. For 40 years, Eugster put his athletic pursuits on the back burner as his children and dental practice grew. But idleness did not sit well with the British sprinting champion so he began re-sharpening his athletic edge in his mid-sixties. Eugster started skiing and pulling oars again, beginning a remarkable run in competitive sports. For two decades, he went on to dominate senior rowing, winning 36 masters gold medals.