Persons who trained for a marathon showed improvement in age-related aortic stiffness and reduction in blood pressure in a study of 138 first-time completers of the London Marathon.
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Compared with pretraining values, the descending aortas of marathon completers were 9% more distensible at the level of the bifurcation of the pulmonary artery and 16% more distensible at the level of the diaphragm (P = .0009 and .002, respectively). There was no change in distensibility of the ascending aorta.
Additionally, central systolic BP dropped by 4 mm Hg and diastolic BP by 3 mm Hg by the time marathon training was completed.
“Training and completion of a first-time marathon result in beneficial reductions in BP and intrinsic aortic stiffening in healthy participants,” concluded Anish Bhuva, MBBS, and coinvestigators. “These changes are equivalent to approximately a 4-year reduction in vascular age.”
The study points to a role for exercise in the reduction of arterial stiffness, a known aging-related contributor to cardiovascular disease for which there currently is no good pharmacologic option, said Julio Chirinos, MD, Phd, in an accompanying editorial (J Am Coll Cardiol. 2020 Jan 6. doi: 10.1016/j.jacc.2019.11.007). The challenge lies in implementing exercise interventions on a large scale in societies where “there remains an immense paradoxical gap” between the known benefits of physical activity and increasingly sedentary populations, he added, calling for increased implementation research.
Using cardiovascular magnetic resonance to assess aortic distensibility, Dr. Bhuva, of the Institute of Cardiovascular Science, University College London, and colleagues assessed aortic BP and aortic stiffness at two points via the noninvasive imaging method. The first assessment was conducted before the study participants began marathon training; the second was obtained between 1 and 3 weeks after marathon completion, after any acute effects of the marathon had abated.
Anthropometric data, peripheral BP, and aerobic capacity (peak VO2) were also assessed at both study points.
Although the study wasn’t designed to track individual training regimens, first-time London Marathon participants were given a 17-week “Beginner’s Training Plan” by event organizers, and asked to follow the plan while participating in the study. The goal of the beginner’s plan was marathon completion, with a schedule of about three runs weekly increasing in duration and intensity over the training period.
Participants had to be first-time marathon participants and running less than 2 hours per week at enrollment. Only those who completed the marathon were included in the data analysis, though baseline characteristics didn’t differ between completers and those who dropped out.
For 2016, the first study year, only participants aged 18-39 years were included, while in 2017, all ages were included in the study. The final age range was 21-69 years, with a mean age of 37; 51% of participants were female. Those with a history of hypertension or taking antihypertensive medication and those who had other significant medical conditions were excluded.
The differential increase in distensibility along the length of the aorta reflects known differences in tissue composition, agreed the authors and Dr. Chirinos, a cardiologist at the University of Pennsylvania, Philadelphia. In addition to the magnetic resonance–obtained distensibility measurements, the investigators conducted further calculations to adjust for baseline mean central arterial pressure, since arterial stiffness is a function both of intrinsic tissue characteristics and loading conditions.
In youth, aortic distensibility buffers the effect of pulse pressure on both the left ventricle and the peripheral vascular system. As the aorta and other large arteries stiffen predictably with age, isolated systolic hypertension can result. The stiffening “also favors adverse patterns of pulsatile left ventricular overload,” which can lead to left ventricular remodeling and, eventually, heart failure, noted Dr. Chirinos. Reduced aortic pliancy also allows pulse pressure variation to be transmitted downstream “into the microvasculature of target organs (such as the kidney and brain) that require high blood flow and thus operate at low arteriolar resistance,” he added.
The assessment that marathon training reversed aortic age by a median 3.9 years was derived from the baseline cross-sectional data regarding participants’ age and aortic stiffness. The effect size was largest in those older than 37 years and in those with higher baseline systolic BP, and men saw greater benefit by a median 1.4 years. Those with slower running times also saw greater benefit.
Study participants had small but significant reductions in heart rate, body fat percentage, and weight by the postmarathon assessment, but these differences were not associated with changes in aortic stiffness. Aerobic exercise capacity as measured by peak VO2 didn’t change significantly from pre- to post training, but the fact that participants were semirecumbent during exercise testing (to allow concurrent echocardiography) may have affected results.
The real-world design of this study had the strengths of assessing free-living, healthy individuals who participated in a self-directed training plan. Dr. Bhuva and coauthors acknowledged that marathon training may include changes in diet, sleep, and other potentially confounding lifestyle factors, as well as improvement in lipid and glucose metabolism. Further, noted Dr. Chirinos, there was no control group. Also, results from individuals training for an endurance event may have limited generalizability to the general population.
Still, said Dr. Chirinos, the innovative study design took advantage of a large-scale athletic event to see how a realistic training regimen affected healthy individuals. “Perhaps the contemporary marathon can teach us some lessons about exploiting the confluence of interests of the general public, media, industry, scientific community, and government to accomplish worthy goals at the individual and societal levels.”
The study was funded by the British Heart Foundation, Cardiac Risk in the Young, and the Barts Cardiovascular Biomedical Research Centre. Exercise testing equipment and technical support were provided by COSMED. Dr. Bhuva reported receiving funding from the British Heart Foundation. Dr. Chirinos reported having been a consultant or receiving research funding from multiple pharmaceutical companies and Microsoft; he is also an inventor of University of Pennsylvania–held patents for cardiovascular pharmaceutical agents.
SOURCE: Bhuva A et al. J Am Coll Cardiol. 2020 Jan;75(1):60-71.