What is the single biggest risk factor for cardiovascular disease?
Elevated blood pressure? Obesity? High cholesterol?
That’s right. Age is the single biggest risk factor for developing cardiovascular disease — the older we get, the greater our risk.
Why does the passage of time confer such a drastic risk on our cardiovascular health? This has to do largely with one single process — the stiffening of our arteries, in particular, our aorta — the largest artery in the body with the most important functions. The aorta is the main valve through which blood is distributed from the heart to the rest of the body. A compliant (think “stretchy”) and powerful aorta is crucial for our cardiovascular performance and long-term health.
“Normal aging” does a number on our aorta — increasing the amount of collagen in the wall and reducing its elasticity. As a result, the aorta gets stiffer with age. This is traditionally seen as a “natural” consequence of aging.
But natural it might not be.
In fact, several studies show that lifestyle factors (mainly exercise) can drastically alter the trajectory of aortic aging.
Whether by preventing stiffening in the first place or reversing stiffness that has already occurred, exercise is “medicine” for the aged aorta.
A newly-published study lends more support to the profound anti-aging effects of aerobic exercise, showing that even in apparently “healthy” individuals, aerobic exercise training can seemingly reverse “biological age”of the arteries.
Running a marathon might be more than something to brag about on Instagram. Indeed, as summarized in the article “Training for a first-time marathon reverses age-related aortic stiffening”, adopting even a mild-volume marathon training program exerts impressive cardiovascular effects, and might even turn back the arterial clock.
Published in the Journal of the American College of Cardiology (JACC), this study analyzed a cohort of 138 individuals (average age of 37; 49% of whom were men) who signed up for and completed the London Marathon. These people had never seriously trained for (or finished) a marathon (their typical training was <2 hours/week). This fit with the goal of the study — which was to see how adopting a loosely structured training program impacts the arteries of “untrained” individuals.
The training program adopted here was indeed “loosely” structured. While this could be seen as a “limitation” of the study (a lack of control), it also complemented the study purpose; which was to investigate a “real world” scenario where participants could essentially choose their volume and intensity of training outside of a laboratory setting.
The general training paradigm called for at least 3 runs/week, with a progression over 17 weeks leading up to marathon race day. The explicit goal for the runners was “marathon completion” — the plan wasn’t designed to drastically improve their cardiovascular fitness (V02 max) or produce six-pack abs.
Your standard health biomarkers like height, weight, blood pressure, and cardiovascular fitness were taken for all participants to gain insight into the demographics of the group as a whole and determine how exercise training would impact anthropometric variables. These and all other study measurements were taken before and after the marathon program.
To measure aortic stiffness, this study used cardiac magnetic resonance (CMR) — which is essentially an MRI of the aorta. Using MRI allows researchers to visualize in real time changes in the diameter and area of the aorta throughout the cardiac cycle. Using this data along with measurements of pressure (blood pressure), one can calculate how much the aorta distends or “stretches” in response to pressure; which gives us a measure of how elastic (distensible) the aorta is.
Accordingly, the two main outcome measures in this study were aortic distensibility and aortic beta-stiffness. A higher distensibility indicates less stiffness, and vice-versa for beta-stiffness — where higher is worse.
MRI was performed on three different segments or regions of the aorta. Another measurement called pulse-wave velocity (PWV) was also measured. PWV analyzes how fast a pressure wave travels from the aorta when the heart contracts — with a faster speed indicating a stiffer aorta.
All “baseline” measurements were made an average of 176 days before the marathon, and “post” assessments occurred about 16 days after race day. Let’s take a look at the general “running statistics” for the group.
Average race completion time:
Men: 4.5 hours
Women: 5.4 hours
Estimated weekly training volume: 6–13 miles
We won’t judge here, but needless to say, these aren’t record-breaking stats. However, this makes the study all the more intriguing. Given the results, this implies that you need not engage in elite-level training or racing to achieve benefits of exercise. Just some will do.
Let’s talk blood pressure. On average, the training program reduced brachial artery systolic and diastolic BP by 4 mmHg (from 120 to 116 for SBP) and 3 mmHg (from 75 to 72 for DBP). Similar results were found for aortic systolic and diastolic BP, which fell 4 mmHg (from 110 to 106 for SBP) and 3 mmHg (from 76 to 74 for DBP). Interestingly, training had no effect on resting heart rate.
Even with the “low” amount of training in this study, aortic stiffness was reduced significantly. In two of the aortic segments analyzed (the proximal descending aorta and thoracic descending aorta), distensibility was increased by 9% and 16%, indicating that these arterial segments became less stiff with training.
Beta-stiffness (the opposite of distensibility) followed a similar but reverse pattern, with a reduction of 6% observed in each of the aortic regions mentioned above. Reductions in PWV were also observed in both regions of the descending aorta analyzed.
Interestingly, the benefits weren’t reaped equally by all. While older participants and those with higher blood pressure experienced greater improvements overall, it was older men with a slower marathon finishing time who received the most benefit from training.
These stiffness improvements are impressive, but perhaps the most interesting finding was what happened to “biological age” of the participants’ arteries throughout the training study.
When various calculations were run by the researchers, it was shown that improved distensibility in the various regions of the aorta translated to a “reversal” of biological age by 1.5, 3.9, and 4 years! When the same calculations were made for beta-stiffness, biological age was estimated to be reversed by 0, 2.4, and 3.2 years, on average. In essence, training made the arteries of older participants more similar to people 4 years younger.
While not the main focus of the study, it is worthwhile to note that body fat % was reduced in after training and upon further analysis, it appears that the older participants experienced the bulk of the reduction — losing about 2% body fat throughout the study.
Not too shabby for just around 5 months of exercise training.
A few things stand out about this study.
The first, which I mentioned before, is the almost surprising fact (surprising to me at least) that such a “minor” amount of training could lead to the significant beneficial adaptations that it did.
Just ~5 weeks of training at right around the bare minimum exercise recommendations (which call for 150 minutes/week) was sufficient to reverse biological aging of the arteries and reduce blood pressure to a similar magnitude seen in people using blood pressure lowering medications!
What is even more interesting is the fact that these changes occurred without a substantial increase in V02 max (maximal aerobic capacity or cardiovascular “fitness”). While V02 max did change slightly and significantly (from 34.5 to 35.6 ml/kg/min, this isn’t a radical improvement by any means.
This implies that even without “training” your fitness, you can “train” your way to healthier arteries.
And it’s never too late to “turn back the clock”. Older participants in this study improved their arterial health to a greater extent than the younger participants. Perhaps they had more to improve upon…or perhaps the effects of aging are more malleable than we think.
Anish N. Bhuva et al. Training for a First-Time Marathon Reverses Age-Related Aortic Stiffening, Journal of the American College of Cardiology, Volume 75, Issue 1, 2020, Pages 60–71
Julio A. Chirinos, The Run Against Arterial Aging,
Journal of the American College of Cardiology,
Volume 75, Issue 1, 2020, Pages 72–75