The Mind-Blowing Science of Aging and Running: Can You Stop the Clock?
Athletes are naturally predisposed to treating their bodies like temples. After all, each small variable plays a big role in performance, from sleep and recovery to nutrition and hydration. For many runners, however, the factors that can’t be controlled are most worrisome. The role of aging on athletic performance is a vast scientific field, with fascinating research emerging from many different venues. What is it about reaching the “master’s” milestone that seems to immediately affect performance? The surprising science, as well as how you can slow down the clock, is described here.
How Does the Body Change with Age?
Perhaps the most important change that our bodies undergo as we age is a decrease in efficient oxygen uptake1. Formally, this is known as VO2 max, or, the maximum volume of oxygen uptake. At a basic level, VO2 max describes the greatest amount of oxygen that can be utilized at the cellular level during exercise. In general, the higher a person’s VO2 max, the better the person’s athletic performance.
Essentially, even though respiration rate stays constant throughout life (assuming relative fitness) the amount of oxygen able to be extracted from each breath for use in the muscles decreases if training remains consistent over the years. Scientists estimate that VO2 max decreases 30 – 40%2 per decade for healthy men and women after the age of 40.
In addition to changes in VO2 max, the entire cardiopulmonary system undergoes performance-detracting alterations. The cardiopulmonary system describes the combined function of the heart and lungs. The physical changes in these organs are most likely to affect performance and are among the least controllable. As lung and heart capacity decreases with age, blood vessels and arteries are less efficient at pumping blood throughout the body.
The heart continues to grow throughout our lives, but the proportions of the two ventricles change. The relative size of the left ventricle decreases, which is utilized for pumping newly oxygenated blood throughout the body. In addition, stroke volume diminishes; meaning the amount of blood pumped with each heartbeat is less than in previous years. This change affects cardiac output, which is the total amount of blood pumped by the heart per minute. Decreased stability and flexibility of blood vessels also play a role in diminished cardiovascular capability.
The aging lungs are less able to draw in oxygen and expel carbon dioxide due to a weakening of the diaphragm. Alveoli in the lungs (i.e., sacs in the lungs where oxygen and carbon dioxide are exchanged) diminish with age, both in size and number. When the cardiopulmonary system is considered as a whole, the combination of decreased oxygenation rates in the lungs, and the hindered ability of the heart to pump out oxygenated blood leads to poor respiration. In fact, maximum breathing capacity at 80 years old is approximately 40% of that of a healthy 30-year-old.
As adults grow older, blood pressure3 tends to increase as well. In general, runners have healthier blood pressure than non-runners. However, the thickening of arteries over time due to poor diet, poor genes, or a combination of the two can increase cardiopulmonary stress. During a run, systolic blood pressure, how hard your blood pushes against artery walls, naturally rises. Athletes who continue to train into old age can expect increased stress on their bodies due to these changes.
In terms of metabolism, it is all downhill after 30. Scientists estimate that metabolism slows 2 – 4%4 each year after you reach 30 years old. Therefore, if your fitness and workload stay the same annually but the amount you eat remains constant, you are likely to gain weight and see minimal decreases in performance. In addition, a slower metabolism will hinder thermoregulation, or, the body’s heating and cooling efficiency. In the cold, a master runner will have difficulty retaining warmth; while in the summer months, the ability to cool oneself via sweat will be diminished.
As we age, the elasticity in our muscles, ligaments, tendons, and joints decreases5. As flexibility decreases, stride length will change, as will the ability to ward off injury. With connective tissue becoming more brittle with age, injuries such as tendonitis and muscle tears/strains become increasingly likely.
A well-known change in aging adults is decreased muscular power output6. Declines in muscle mass, variations in muscle composition, and changes in muscle quality all affect the amount of power put forth by the master’s athlete.
After reading about everything that declines with age, are you ready for some good news? As runners grow older, their overall running economy7 (i.e. total efficiency) does not change significantly. Therefore, if you can mitigate the changes described above, there is still hope in retaining a fair amount of fitness.
How Does Running Slow the Aging Process?
In the first-ever study of its kind8, Stanford University School of Medicine researchers have tracked more than 500 Americans, aged 50+, since 1984. At the start of the study, many scientists hypothesized the newfound running boom would have a deleterious effect on health in the aging population, particularly that of bones and joints. The purpose of this study was to observe long term trends in the running versus non-running populations in what became known as the “compression of morbidity theory.”
The ability to perform simple functions decreases with age, but runners appear to maintain their physical capabilities for a much greater period of time than non-runners. On average, runners became disabled (based on answers to Health Assessment Disability Index) 16 years later than non-runners. As the aging process continues, the range of relative abilities continues to widen as well. Even as runners in the study entered their 90’s, the ability gap continued to grow.
As of 2008, when the majority of the study’s participants were in their 70’s and 80’s, only 15% of the study’s 284 participants had died. In comparison, 34% of the 156 non-running cohort had passed away. Not surprisingly, non-runners had an increased risk of cardiovascular disease, as well as cancer and neurological disorders. Even though runners were exercising significantly less often than when the study began (running an average of 76 minutes per week as opposed to 4 hours), the benefits of even minimal exercise were great.
As for the initial theories in the 1980’s that runners would be more prone to orthopedic injury, those hypotheses fell flat. Instead, research showed that non-runners were more likely to require complete knee replacements later in life, as well as develop osteoarthritis.
How Much Do Runners Slow Down with Age?
So far, we have discussed various factors that lead to a runner slowing down with age, but no quantification of the effect. There have been numerous attempts to determine exactly what to expect as a runner ages, each with slightly varying results.
0.2% per year
A 2010 study followed 200,000 participants of a 15k road race9 over a period of 12 years. By compiling age group data throughout the study’s time period, researchers determined that runners can expect to slow down only 0.2% per year after their 40th birthday. Additionally, men appear to be affected by age more than women. Prior to age 40, men were consistently ~15% faster than women. However, by the time runners hit the age of 60, women became reliably 10% slower than men. According to this study, one can expect to slow down approximately 1 second per mile, per year.
1 – 1.4% per year
A separate study, also performed using race data, showed a more pessimistic result that runners can expect to slow 1 – 1.4% per year. Here, researchers used 16 years of data from the New York City Marathon10 to track the progress of aging athletes.
0.5% per year
What about highly trained runners? In a 2003 study11, male athletes aged 21 – 63 who had run between 31 and 40 minutes in the 10k were examined. Scientists used historical data as well as physiological testing to determine that athletes who stay in peak condition annually can expect a 0.5% yearly decline after the age of 40.
In each of these three cases, it should be noted that race data may not be wholly reliable. For instance, these studies do not take into account variations in weather or the generalized slow-down of race participants since the 1980’s.
Can You Fight the Aging Process?
Now that you know what the master’s athlete is up against; is there any way to slow down this process? In short, while you cannot fight aging entirely, you can reduce the amount you are slowed with proper training.
VO2 max workouts
Since the ability to efficiently uptake oxygen is one of the greatest detractors in the performance capability of an aging runner, it is important to continually train the aerobic system. Interval work at aerobic capacity, such as 6 x 1000 m at 5k race pace with 3:00 rest, is a key component in maintaining cardiovascular strength.
To overcome the declining muscle power that master’s athletes face, the solution is to lift more frequently. Not only will strength training fight muscle loss, but it will jumpstart metabolism and prevent the permanent degradation of fast twitch muscle fibers, according to Scott Trappe of Ball State University’s Human Performance Lab.
Maintaining muscular elasticity is also important for the aging runner. Incorporating regular stretching and yoga routines into training can circumvent the diminishing flexibility experienced by the aging population.
As metabolism decreases, it is important to keep caloric needs in mind. The body will require less fuel in order to sustain energy, and the quality and nutrient density of the diet will be important as well. Research has also suggested that a high fat diet can hinder VO2 max, so it is important for the master’s runner to eat appropriate for their specific needs.
Finally, a factor not discussed in detail is that the aging athlete will recover at a slower rate12 than a runner in his or her 20’s. Since running economy has been shown to remain stable into older age, high volume training is no longer a necessity. Instead, quality should be the main focus for a master’s runner, with plenty of recovery days in between all-out efforts.
1. Betik AC, Hepple RT. Determinants of VO2 max decline with aging: an integrated perspective. Appl Physiol Nutr Metab. 2008; 33: 130–140. doi: 10.1139/H07-174 Link
2. Karavidas A., Lazaros G., Tsiachris D., Pyrgakis V. (2010). Aging and the cardiovascular system. Hellenic J. Cardiol. 51, 421–427. Available online at: http://www.hellenicjcardiol.org/archive/full_text/2010/5/2010_5_421.pdf
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11. Stephen R. Bird, Simon C. Theakston, Andrew Owen, Alan M. Nevill. Characteristics Associated with 10-km Running Performance among a Group of Highly Trained Male Endurance Runners Age 21–63 Years. doi: http://dx.doi.org/10.1123/japa.11.3.333 Link
12. Borges N, Reaburn P, Driller M, Argus C. Age-Related Changes in Performance and Recovery Kinetics in Masters Athletes: A Narrative Review. J Aging Phys Act. 2016 Jan;24(1):149-57. doi: 10.1123/japa.2015-0021. Epub 2015 Apr 16. Link