Ageing: can we turn back the clock?

Being active matters!

We all want to grow older gracefully and continue to stay active and independent. There are several factors that dictate how well we age and the trajectory of our physical decline. These include biological ageing, genetics, and modifiable factors such as physical activity levels, and nutrition.

In western society however, physical activity generally declines as we age. Less than 20% of people >50 years meet the recommended activity guidelines by the Center for Disease Control and Prevention (CDC) and World Health Organization (WHO). The health consequences are large because of the protective effects of activity from diseases such as cardiovascular disease, cancer, and diabetes, and physical functional decline. In contrast, older athletes who are very active provide some insight into the decline in function due to primarily ageing alone. Also, comparisons between active and inactive older adults highlights the advantages of exercise.

Can you turn back the clock on aging?

Being active can delay the clock, adding years of better-quality life, but it cannot not stop the clock.  What does this really mean and how much activity matters? 

Many physiological systems in our body — muscular, nervous, and cardiovascular—decline in how they function as we age. This impacts our physical performance. These reductions occur even in very active older adults such as master’s athletes. That is why world records of athletic events decline with increased age. For example, maximum heart rate starts to lower at about 1 heartbeat per year from ~20 years of age (Maximal Heart Rate = 220 – Age). [Note, there is considerable of variation between individuals]. This decline in maximal heart rate occurs no matter how active or inactive you are and impacts the rate of blood transport around the body. Blood carries oxygen to the muscles. As our maximal heart rate declines with age so does the opportunity for working muscles to utilise oxygen with a loss of ~10 % per decade. There are other components of human anatomy that can be preserved with high levels of activity. This also means they are more susceptible to activity-related declines. This includes include blood pressure, stiffness of the arteries, heart volume and skeletal muscle to name a few. Consequently, while physical and functional decline does occur with ageing, it can also be offset by staying active. Below is an excellent example.

Active women have a 10-year strength advantage!

In a research study at the University of Sydney on 217 Australian women, I showed that women who were active (~3 times a week or more) resulted in a 10-year strength advantage over those women who were not as active and who performed exercise less than 3 times a week. The figure below illustrates this more clearly. Shown is the average leg strength of the active women (in red) and inactive women (in green). [Note the average decline in leg strength is graphed for each group for simplicity]. The horizontal dotted line at 100 Nm represents the theoretical leg strength needed for a given activity (e.g. getting out of a chair). Once the strength of the active or inactive women drops below that horizontal line, the task cannot be performed without assistance. The inactive women reach this point at 63 years and the active women at 73 years. The main point is that because the active women are stronger at every age, they will be able to successfully perform that activity for 10 years longer than the inactive women.

Figure 1. Leg (quadriceps) strength of 217 Australian women across different ages (20-85 years). Leg strength of the women (as torque) is on the left vertical axis and the age of the women on the horizontal. Leg strength declined with increased age for both active and inactive women. The dotted line (starting at 100 Nm) is the leg strength (theoretical) needed to do an activity such as rising from a chair. The leg strength of the inactive women reached this strength threshold needed to perform the task 10 years earlier (at 63 years) than the active women (at 73 years). Thus, the active women had a 10-year strength advantage. Data from Hunter et al J Gerontology 55A: B264-B273, 2000.

This is real data on real people.  The key message here is: be active.  Adhere to the clear international activity guidelines for recommended activity levels of 150 minutes of moderate intensity exercise per week or 75 minutes of intense exercise.  For older adults, strength training twice a week is also recommended.

To help you be active, try some of the My AgeFit exercise challenges from 2020.