Physical activity to prevent chronic diseases

February 3, 2022

Dr Deborah Lee from Dr Fox Online Pharmacy, considers the role of physical activity to prevent chronic diseases

This article explores the extent to which regular physical activity helps improve your overall health, fitness, and quality of life and how it helps to reduce the risk of chronic conditions like type-2 diabetes, heart disease, cancer, depression and anxiety plus dementia.

Lack of physical exercise has been formally classified as a major cause of chronic disease and death. Research suggests physical inactivity is equally as harmful to health, as a poor diet and smoking. These facts may come as a surprise to some. But when you think about it, it’s not surprising at all. Our bodies were meant to be used, and just like anything in life, you use it or lose it.

In a 2018 detailed and comprehensive review of the health benefits of exercise, the authors report there is ‘overwhelming evidence’ from over 100,000 medical publications, that regular physical exercise prolongs our natural lifespan and prevents more than forty chronic diseases.

Cardiorespiratory fitness (CRF)

Exercise is the best way to improve cardiorespiratory fitness (CRF). This is measured by improving the maximal oxygen uptake, VO2max. Each unit of metabolic improvement results in a 12% reduction in mortality. In one 2010 study, men with a low CRF who increased their fitness over an eight-year period, reduced their risk of death by 50%. However, this was also true in reverse, as those who transitioned from high to low CRF, increased their risk of mortality by 50%.

When we exercise, this improves our ability to transport oxygen by improving cardiac output. It also facilitates the diffusion of oxygen within working muscle tissue, enhancing the growth and development of capillaries, and augmenting the myoglobin muscle content. In addition, exercise leads to an increase in the density of mitochondria and improves mitochondrial efficiency in providing energy output.

Type-2 diabetes (T2D)

Type-2 diabetes (T2D) is also inexorably linked to a lack of physical exercise. In a large 2006 Chinese study, 110,366 men and women with abnormal glucose tolerance and at high risk of T2D, were randomly assigned to one of four groups; controls, diet only, an exercise, and a diet plus exercise group, and followed up for six years. T2D developed in 67.7% of the control group, compared to 43.8% in the diet group, 41.1% in the exercise group and 46% in the diet plus exercise group. Statistical analysis revealed that the exercise group had the greatest significant reduction in the risk of T2D – an overall risk reduction of 46%.

Why should this be? Insulin resistance is the prime underlying cause of T2D. In T2D, there is plenty of insulin, but cells have become insensitive to it, hence glucose is not taken up inside them, and they are relatively starved of glucose. However, in those with insulin resistance, when they exercise, this problem is bypassed, because skeletal muscle cells take up glucose through a separate pathway that does not require insulin. Indeed, glucose uptake is increased more than 50-fold in exercising muscle.

This is one-way exercise helps improve blood glucose control and facilitates weight loss. Increasing physical exercise is seen as a vital tool for combatting the current T2D epidemic.

Mental health

Numerous studies have demonstrated the benefits of increased physical activity on brain function, in both cognition and mental health. Physical exercise reduces

the risks of conditions such as depression, anxiety, Alzheimer’s Disease and Parkinson’s Disease. Exercise results in an increase in brain-derived neurotrophic factor (BDNF) – a protein responsible for the growth, differentiation, and synaptic connections of neurons. BDNF is important for neuroplasticity – the construction of new neuronal pathways.

Other factors are also important. For example, exercise increases levels of insulin-like growth factor (IGF-1), a hormone that acts as a cell-signalling molecule and has a prime role in brain development and ageing. Exercise also leads to an increase in the concentration of brain neurotransmitters including dopamine, glutamate, serotonin and noradrenaline – all of which produce a natural high and elevate mood.

Cancer

Robust evidence exists to support the fact that increased exercise reduces the risk of cancer. This applies to thirteen different cancers, including breast, bladder, colon, kidney, oesophagus, endometrium and stomach.

It is difficult to single out physical inactivity from being overweight or obese, as these often go hand in hand. However, the medical literature supports a very

convincing link between both these factors and an increased risk of cancer. What seems to be important is maintaining an appropriate balance between calorie input and energy expenditure, as this is vital for the primary prevention of cancer.

As an example, in 2001, being overweight or obese, and/or physically inactive, was estimated to cause 26% of colorectal cancers worldwide. Yet physical activity is a modifiable risk factor, along with diet, smoking, addictive behaviour and poor sexual health. Men and women with a BMI of over 40, have a 52% and 62% respective increased risk of dying from cancer, as compared to those with a BMI of less than 25.

Probable explanations include the following. Exercise lowers levels of hormones such as oestrogen and other growth factors which are important for the growth and development of cancers. It also reduces insulin resistance and improves glucose metabolism, thus improving cellular function. Increasing physical activity also lowers levels of chronic inflammation and reduces oxidative stress, which is known to be associated with DNA mutations. Exercising regularly helps to combat obesity – obesity itself being a risk factor for cancer.

To what extent is lack of exercise a major cause of chronic diseases today?

Heart disease

The British Heart Foundation reports that 5 million deaths from heart disease around the world are caused every year due to lack of physical exercise. This accounts for one in six UK deaths.

Type-2 diabetes

Physical inactivity is thought to account overall for 7% of the cases of T2D in Europe. Being overweight or obese accounts for 65%-80% of new cases of T2D – but physical inactivity and being overweight or obese often coexist. Furthermore, only 34% of young people aged 13-15 are doing enough exercise to meet current recommendations.

Mental health

In a 2018 American study of 1.2 million adults, on average, study participants reported experiencing 4.3 poor mental health days per month. Those who did regular exercise, however, had one and half days fewer poor mental health days every month than those who did not exercise, meaning exercise resulted in a 43% reduction in poor mental health. The authors recognised the numerous benefits of exercise on mental health, but these included, in particular, the positive effects of social interaction, connecting with others and the consequent improvement in emotional resilience.

The Alzheimer’s Society reports that taking regular physical exercise in middle age can reduce your risk of developing Alzheimer’s Disease by around 45%. Regular exercise in older people has also been shown to improve cognition, memory and brain processing speed.

Cancer

Cancer is most often not caused by bad luck. However, whereas many people recognise smoking and obesity as risk factors for cancer, they are often unaware of the equal importance of a lack of physical exercise.

In a 2015 study from a head and neck cancer clinic, those who reported a lack of physical activity were more likely to have a malignancy compared to those who took regular exercise, irrespective of their BMI or smoking history.

What are the health benefits of exercise for those with a chronic disease?
How can exercise improve a chronic condition?

Let’s take exercise and T2D. Those with diabetes tend to have weaker muscle power, take fewer steps, and have lower CRF. But exercise, even a gentle exercise such as walking, in small amounts, can have demonstrable benefits.

Numerous studies have shown that walking reduces the risk of T2D. From the Nurses Health Study, those who walked at a normal walking pace had a 20%-30% reduced risk of developing T2D. In another study, diabetics who walked at least two hours per week had a 39% lower all-cause mortality and a 34% reduction in death from cardiovascular disease than those who were sedentary. Other studies have linked an increased number of steps taken per day with a lowered risk of heart disease. Taking 8,000 to 10,000 steps per day was found to reduce the risk of developing metabolic syndrome.

In one 2005 Japanese study, the authors introduced a list of easy to incorporate, common sense, exercise goals into daily life. They asked the study participants to walk for 30 to 40 minutes every day, to take the stairs, not the lift, to cycle for 30 minutes at the weekend, and get off the bus one stop earlier and walk the last route home. By doing this, participants reduced their risk of T2D by 67.4%.

In terms of managing T2D, walking when combined with dietary modification, has been shown to lower insulin resistance and help facilitate weight loss.

It doesn’t have to be walking. Anything that gets you up out of a chair and moving is a form of activity that can be measured in terms of metabolic equivalent. Here’s a list:

Walking very slowly – 2
Walking slowly – 2.8
Walking moderately – 3.5
Walking briskly – 4.3
Walking very briskly – 5
Climbing stairs slowly – 4
Climbing stairs fast – 8
Gardening – 3.8
Mowing the lawn – 5.5
Housework – washing up – 1.8 – 2.5
Cooking – 2- 3
Childcare – 2
Elderly care – 2.3 – 4

Your basal metabolic rate is 1 MET. So, you can see that just getting up and getting busy in the home starts to increase your metabolic energy consumption.

Non-exercise thermogenesis (NEAT)

NEAT is the energy your body expends when you are not taking physical exercise. The important thing to note is that NEAT has been shown to increase by 25% in the seven days after taking a single episode of exercise. Studies have shown that those living in rural areas have higher levels of NEAT than those who live in cities. It may be due to the lifestyle issues associated with more walking in a more rural environment.

NEAT is affected by other factors including diet, daily exercise and the living environment. It is also under the influence of hormones such as thyroxine, leptin, reproductive hormones, and orexin. Research has also identified specific genes, for example, genetic variations of the dopamine D2 receptor gene and melanocortin-4 receptor gene, both of which affect the motivation to exercise.

Current UK exercise recommendations

UK adults are currently recommended to undertake 150-minutes per week of moderate-intensity exercise

(MIT). This is exercise sufficient to quicken your pulse and make you feel a bit sweaty and out of breath. This should be done in intervals of 30-40 minutes a day, on four or five days per week. An alternative is 75 minutes of vigorous exercise twice a week.

MIT options include walking, jogging, cycling, swimming and dancing.

To lose weight, however, it is advisable to increase your exercise regime to 300 minutes per week – that’s 60 minutes a day, five days a week. Remember this does not have to be done all in one go, it could be two half sessions a day, or three, twenty-minute sessions, for example.

High-intensity training (HIT) is an alternative fitness option. It involves intense episodes of vigorous exercise lasting 10-60 seconds, followed by a recovery period, and repeated up to 10 times. This is a specific type of exercise designed to improve wellbeing and physical fitness.

To what extent does physical activity contribute to the prevention and management of mental health conditions in children, adolescents and adults?

Getting enough physical exercise has long been recognised as vital for the health and wellbeing of children, including for their mental health.

A 2019 systematic review of 26 different studies concluded that exercise was associated with lower levels of depressive symptoms and depression, as well as increased self-confidence and self-esteem. The best outcomes were noted after regular, supervised, group activities.

In young people, depression and anxiety are common in those who do not participate in regular exercise and spend a lot of time online. In one 2015 Chinese study, 16.3%, 15.9% and 17.3% of students were suffering from anxiety, depression and psychopathological symptoms, respectively. Both low physical activity and high levels of screen time were linked to poorer mental health.

In the COVID pandemic in 2020, 94,000 fewer children were taking enough physical exercise, compared to pre-pandemic levels. The worst affected age group were seven to nine year olds where only 38% were getting enough exercise. Black children were also severely affected with only 36% getting enough exercise.

During the pandemic children’s screen time also increased considerably. In one survey children aged under 14 were spending approximately 23 hours a week on their smartphones or computers. Excess screentime is linked to a less healthy diet, obesity, poor sleep and poorer mental health. Parents are recommended to restrict screen time, take an interest in what their children are doing online, have screen- free mealtimes, leave mobile phones switched off and outside the bedroom door at night, and encourage them to do some more physical exercise.

Older adults have many barriers to exercise. They often lack confidence, worrying they will do themselves an injury, feel self-conscious, may suffer from chronic health problems such as arthritis that makes exercise painful, may already suffer from depression linked to inertia and may lack the finances to pay for a gym membership or exercise classes. In fact, all these barriers can be got around.

Many gyms and leisure centres run exercise sessions, especially for older people. The NHS funds exercise in that the GP can prescribe exercise as a treatment. Many conditions, including arthritis, are improved by exercise. One good example is hydrotherapy, and indeed swimming, for those with osteoarthritis of the knee. Encouraging older people to exercise has many advantages for both physical and mental health.

Taking part in exercise is also a very effective way to combat loneliness. Data suggests that over the longer term, being lonely is just as serious a risk to older people’s health as smoking 15 cigarettes a day. However, a recent American study reported on a group of 50-104 year-olds, who were enrolled in a variety of evidence-based exercise classes. After six months, loneliness had reduced by 6.9% and social interaction had improved by 3.3%. In addition, participants were shown to reduce their risk of falls.

One of the best forms of exercise for older people is dancing. This can help improve both physical and mental health.

In a 2009 review in the Journal of Aging and Physical Activity, the authors reviewed 15 training and three cross-sectional studies and concluded there was substantial medical evidence that dancing can significantly improve aerobic power, lower body muscle endurance, strength and flexibility, balance, agility and gait. There is also some evidence that dancing can improve bone mineral density, and muscle power, as well as reduce falls, and risks from cardiovascular disease.

In 2005 McKinley and colleagues reported on a group of frail, elderly with Parkinson’s Disease who had been randomly allocated to either a group learning Argentine Tango or to a group who were walking, as a form of exercise. Although both groups showed improvement in a timed ‘sit to stand’ test, the Argentine Tango group showed greater improvements in balance and walking speed.

Further work in patients with Parkinson’s Disease showed that a twice a week, 10-week Tango Couse, resulted in greater improvements in balance than those in a traditional exercise group. Moreover, the Tango Group were enthusiastic and wanted to continue dancing, and many of the traditional exercise group wanted to join the dance class!

What are the consequences of physical inactivity/sedentary behaviour?

Don’t underestimate the negative effects of spending long hours sitting at your desk. Prolonged sitting has been recognised as a new health hazard. It is estimated that each hour over and above sitting for seven hours a day, increases your risk of premature death by 5%. Those who sit more at work, tend to sit more at home. And lounging around watching TV for long periods has a negative effect on your physical and mental health and overall muscle strength. Prolonged sitting doubles your risk of type-2 diabetes and cardiovascular disease, increases your risk of cancer by 13%, and your risk of dying from cancer by 17%. Scientists regard sitting as being on a car journey, but when you sit for long periods, you put your car (your health) in reverse. The other sad fact is that no amount of physical exercise done before or after prolonged sitting can counteract the negative effects of sitting for long periods.

“Those who think they have not time for bodily exercise will sooner or later have to find time for illness.”

The UK’s Chief Medical officer recommends breaking up long periods of sitting with one to two minutes of physical activity. You can also move more at work by using a stand-up desk for two hours a day, having standing meetings, walking around while taking phone calls, setting an alarm for regular movement breaks, and taking the stairs.

Final thoughts

Exercise is better for the human body than any pill. Yet, why is it so unpopular?

So often we hear people saying they don’t have time for exercise. I loved this quote from Edward Stanley, the Earl of Derby who in 1873 said, “Those who think they have not time for bodily exercise will sooner or later have to find time for illness.”

References