Is the Fountain of Youth as Close as the Seat of a Bicycle?

We may have more control over aging than we think.  New research is revealing that lifelong exercise can have a huge impact on what happens to our bodies as we age.

In the UK in 2014, a group of scientists interested in aging, from the Centre of Human and Aerospace Physiological Sciences, King’s College London and the MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, were considering current knowledge on the subject.  Human life expectancy has more than doubled in the developed world over the past two centuries but declines in physical function with advancing age have increased age-associated disease and frailty so that healthy life expectancy (the healthspan or years of healthy life) is not keeping up with average life expectancy (years of life healthy or otherwise).  In other words, more years near the end of life are being spent with disabilities and in poor health.  The scientists acknowledged that present understanding of the relationship between aging and the functioning of the body was still limited.  (1)

A host of factors impact aging, one of which is physical activity.  Lack of exercise has been shown to accelerate the aging process.  In the world of today, the majority of older people are relatively sedentary and it might be assumed that this is the norm for human beings.  But looking back at the conditions under which our forbears lived, high levels of physical activity were crucial for their survival.    Perhaps being physically active is a requirement for the maintenance of health and a body that functions efficiently over the whole of the lifespan of each human being. (1)

From their deliberations, the UK researchers formulated a new study mandated by the following considerations (1);

• That exercise is the default condition for an optimally functioning body throughout life and so their investigation would require participants who were highly physically active
• That to maintain functional independence over a long lifespan, sufficient muscle mass is a necessity in both males and females, necessitating the inclusion of both genders in their study
• That variables to be measured would focus heavily on systems critical for maintaining physical function and health later in life, particularly elements of the cardiovascular and musculoskeletal systems, but would also include a wide range of other physiological indicators of good health
• That the aims of the study were to determine the relationship between age and function in people who had spent a lifetime practicing sustained but non-elite exercise and to determine if any biological markers of aging could be identified

The 125 participants, adults between 55 and 75 years of age, were recruited from among cyclists in Britain.  The requirements for inclusion in this research were the following (1);

• Maintenance of a high level of physical activity throughout their lives as amateur, non-competitive road cyclists.
• The males were required to have the ability to regularly cycle 100 km in under 6.5 hours
• The females were required to have the ability to regularly cycle 60 km in under 5.5 hours

Data collected from the cyclists was compared with two groups of people who were not partaking in regular physical activity:  75 healthy people aged 57 to 80 and 55 healthy young adults aged 20 to 36. (1)

This study measured a broad range of indicators of the physical condition of the participants.  The results disclosed that cardiovascular and respiratory functions, memories, verbal fluency, balance, reflexes, and metabolic profiles (levels of cholesterol, cortisol, insulin, blood sugar and triglycerides; muscle strength; percentage of body fat; and, in the men, testosterone levels) were not associated with the chronological age of these active men and women. Instead, their health indicators resembled those of a person of around 30 years of age. (1)

This study concluded that the high levels of function within this group of healthy and very active older people were positively correlated with substantial amounts of physical activity.  In other words, it may be possible to defy the aging process through sustained lifelong exercise.  No close association of age with the function of the body was shown through this research, consequently no biological markers were identified that could reliably predict the age of a given healthy individual.  In fact, the scientists found it remarkable that individuals of the same age could differ so markedly in function. (1)

 

SUBSEQUENT STUDIES

Examining aging, exercise and the immune system;

After completing the first study, the same group of scientists resolved to look further into the relationship of physical activity with aging.  It is widely accepted that aging is accompanied by a decline in immune competence which manifests in increased risk of infections, chronic inflammatory diseases and autoimmune conditions as well as in poor response to vaccinations.  A major portion of these effects can be attributed to the weakening of a small gland called the thymus that sits in the upper chest between the lungs and behind the breastbone.  The thymus produces white blood cells called T-cells that are an important part of the body’s immune system (2).  Generally, in early adulthood the thymus begins to shrink, a process that accelerates rapidly after 40 years of age, and T-cell production is reduced.  In addition, aging brings increases in levels of pro-inflammatory cytokines which are predominantly produced by T-cells and macrophages (a type of white cell within the immune system).  These inflammation-producing proteins are also associated with greater risk of age-related disease and death.  (3)

The researchers decided to examine the adaptive immune system in highly physically active people. The human immune system is made up of two parts: the innate (general) immune system and the adaptive (specialized) immune system. These two systems work closely together but they take on different tasks. The innate immune system is the body’s first line of defense against attacks by agents such as bacteria and viruses.  It acts quickly to detect the intruder and destroy it.  However, it has only limited power to stop the danger from spreading.  The adaptive immune system, with its ability to target the specific troublemaker, takes over when the innate system cannot contain the threat. Though it is slower to respond, the adaptive immune system is more accurate.  The adaptive immune system also “remembers” previous attackers so it can respond quickly if the same menace reappears.  The adaptive immune system consists of T-cells, B-cells and antibodies.  (4)

The same groups of participants were used for this new investigation.  They were asked to refrain from vigorous exercise for 24 hours after which a fasting blood sample was taken.  Results from this research demonstrated that the aging cyclists produced almost as many new T-cells in their blood as did the much younger participants.  On the other hand, the older sedentary participants revealed low output of new T-cells from the thymus gland and their glands were shrunken compared to those in younger people.  In addition, levels of other types of immune cells active in preventing autoimmune reactions as well as a hormone that protects the thymus against shrinkage remained high in the cyclists.  Muscles are one of the sources of this thymus-protecting hormone.  All these findings strongly suggest a beneficial effect of long-term physical activity on the thymus and the immune system. (3)

 

Examining aging, exercise and the muscles;

Skeletal muscles generally show loss of tissue mass and experience a reduction in function with aging.  Infiltration of fat and connective tissue into the muscles can also be observed.  However, the extent to which these changes are driven by aging itself has remained unclear.  Many earlier observations were procured from older populations of people without consideration of their lifestyle or amounts of physical activity.  Looking once again at the same group of 125 older male and female cyclists whose lives were characterized by sustained exercise, the same group of investigators analyzed muscle biopsy samples that had been taken from the vastus lateralis muscle on the side of the thigh of 90 of the subjects at the time of the original study.  The hypothesis was that, in these individuals with similarly high levels of physical activity, any changes found in their muscles could be ascribed to aging and not to inactivity. (5)

Their results?  With the exception of the density of the blood-carrying capillaries within the muscles, there was no other association between age and the properties of the muscle tissue samples.  The size, composition, distribution and function illustrated by these muscle samples and the function of their mitochondria (the powerhouses of cells) displayed no age-related deterioration in the older cyclists who were serious exercisers.  In addition, the cyclists who covered the most distance each month on their bicycles possessed the healthiest muscles regardless of age. (5)

 

INPUT FROM THE LEADING COUNTRY IN THE WORLD FOR BICYCLE USE

The Netherlands is well-known for its high cycling levels.  The country has made significant investments in bicycle infrastructure such as dedicated bicycle paths, bicycle parking and traffic calming and, in 2015, approximately 27% of all trips taken in the Netherlands were being accomplished on a bicycle.  According to the Netherlands National Institute for Public Health and the Environment, the average Dutch citizen travels about 1000 kilometers by bicycle every year.

A 2015 study from the University of Utrecht in the Netherlands collected data from about 50,000 Dutch cyclists.  Its results show that (6);

• The average time spent cycling for Dutch adults between the age of 20 to 90 is about 74 minutes per week. This level of cycling is relatively stable over most of adulthood but peaks around the age of 65 to 70 years and drops after the age of 80 years.
• Cycling prevents about 6,500 deaths in the Netherlands every year. This reduction in mortality is a direct result of the average time spent cycling in each age group and therefore it is highest between 65 and 70 years of age.
• The economic health benefits of cycling are estimated at 19 billion euros per year, representing more than 3% of the Dutch Gross Domestic Product between 2010 and 2013. Moreover, this is likely an underestimation of the true total health and economic benefits of cycling since reductions in the incidence of chronic diseases were not taken into account.
• For every 75 minutes per week that Dutch people spend cycling, their life expectancy increases by 1 hour.

 

THE FINAL MESSAGE

It appears that many of the symptoms we call aging may not be inevitable and may in fact be preventable.  This study used cycling to establish that maintenance of a high level of physical activity throughout life can delay the ravages of aging.  It does leave us with a few questions though.  Is it only cycling that can provide these benefits?  Can lifelong participation in any type of serious exercise have a similar effect?  Might comparable benefits be seen after embracing a high level of physical activity later in life?

It is very likely that cycling is not the only physical activity that can put a pause on aging.  However, cycling has much to offer and if you’re looking for a great way to exercise for any reason, cycling is an excellent choice.  It is a low impact aerobic exercise that can enhance your overall fitness level and increase leg strength without stressing joints.  It has been shown to help prevent health issues such as heart attacks, strokes, high blood pressure, and type-2 diabetes. (7,8) Cycling has demonstrated its ability to relieve feelings of stress and anxiety as well as to improve cognitive function. (9)  It is also an environmentally friendly mode of transportation.  And perhaps most important of all, cycling is a lot of fun!  So, jump on that bicycle seat and see where it takes you.  You just might find yourself enjoying a longer healthspan in your future.

 

SOURCES:

1  Pollock, R.D., Carter, S., Velloso, C.P., Duggal, N.A., Lord, J.M., Lazarus, N.R. and Harridge, S.D.R. An investigation into the relationship between age and physiological function in highly active older adults. J Physiol. 2015; 593: 657-680. Doi.org/10.1113/jphysiol.2014.282863.

2  https://www.macmillan.org.uk/cancer-information-and-support/thymus-cancer/the-thymus-gland

3  Duggal, N.A., Pollock, R.D., Lazarus, N.R., Harridge, S., Lord, J.M. Major features of immunesenescence, including reduced thymic output, are ameliorated by high levels of physical activity in adulthood. Aging Cell. 2018; 17:e12750. Doi.org/10.1111/acel.12750.

4  https://www.ncbi.nlm.nih.gov/books/NBK279396/

5  Pollock, R.D., O’Brien, K.A., Daniels, L.J., Nielsen, K.B., Rowlerson, A., Duggal, N.A., Lazarus, N.R., Lord, J.M., Philp, A., Harridge, S.D.R. Properties of the vastus lateralis muscle in relation to age and physiological function in master cyclists aged 55-79 years. Aging Cell. 2018 Apr; 17(2): e12735. Doi: 10.1111/acel.12735..

6  Fishman, E., Schepers, P., Kamphuis, C.B.M.  Dutch Cycling:  Quantifying the Health and Related Economic Benefits.  American Journal of Public Health. 2015; 105: e13-e15.  Doi.org/10.2105/AJPH.2015.302724.

7  Grøntved, A., Koivula, R.W., Johansson, I., Wennberg, P., Østergaard, L., Hallmans, G, Renström, F., Franks, P.W.  Bicycling to Work and Primordial Prevention of Cardiovascular Risk: A Cohort Study Among Swedish Men and Women.    Journal of the American Heart Association.2016;  5(11):  e004413. Doi.org/10.1161/JAHA.116.004413.

8  Jhingan, A., Jhingan, R. M. Effect of Cycling on Glycaemia, Blood Pressure, and Weight in Young Individuals with Type 2 Diabetes. Journal of clinical and diagnostic research. 2017; 11(7): OC09–OC11. Doi.org/10.7860/JCDR/2017/28111.10162.

9  Leyland, L.-A., Spencer, B., Beale, N. et al.  The effect of cycling on cognitive function and well-being in older adults.  PLoS One. 2019; 14(2): e0211779.  Doi: 10.1371/journal.pone.021179.