Training for a first-time marathon has favorable effects on BP and aortic stiffness
Training for a First-Time Marathon Reverses Age-Related Aortic Stiffening
Introduction and methods
Advancing age is associated with histological and biochemical changes that cause vessel stiffening. Progressive stiffening induces changes in hemodynamics, which are associated with dementia, CVD and kidney disease even in the absence of atherosclerosis [1-4]. A potential strategy to modify arterial stiffness is regular aerobic exercise. It has been shown that lifelong athletes have more distensible peripheral arteries . Furthermore, brief (< 3 months) supervised aerobic exercise interventions have a beneficial effect on branchial BP and peripheral artery stiffness [6,7].
It is now possible to examine local arterial stiffness by distensibility in the aorta using cardiovascular magnetic resonance (CMR). The distensibility of the aorta rather than of peripheral arteries is a stronger prognostic marker and more closely associated with natural aging [8-10]. This study aimed to determine whether real-world exercise training for a first-time marathon can reverse age-related aortic stiffening.
138 Healthy participants with no previous marathon-running experience and who ran <2h/week at baseline were followed in this prospective longitudinal observational study. The mean age was 37 ± 10 years (range 21 to 68 years) and 49% were men. Participants were recommended to follow the “beginner’s Trainings Plan” provided by the marathon organizers, which consists of approximately 3 runs/week with increasing difficulty for a 17-week period. However, participants were free to follow an alternative, higher-intensity, or longer training plan if they wished.
Peripheral BP, central BP, anthropomorphic and cardiopulmonary exercise test assessments, and CMR were performed 6 months (176 ± 11 days) prior to the London marathon and 16 ± 4 days after completion of the marathon. Due to the varying regional tissue composition of the aorta, local arterial stiffness was measured by distensibility at the ascending aorta (Ao-A), proximal descending (Ao-P) and diaphragmatic descending aorta (Ao-D). The β-stiffness index was additionally calculated as a pressure-independent measure of intrinsic arterial stiffness.
- Based on baseline data, a decade of chronological aging was associated with a decrease in distensibility in de Ao-A, Ao-P and Ao-D by 2.3, 1.9 and 3.1 x 10^-3 mmHg and an increase in β-stiffness by 27%, 22% and 16%, respectively.
- Brachial SBP and DBP decreased with training by 4 mmHg (95%CI 2.8 to 5.5 mmHg, P<0.01) and 3 mmHg (95%CI: 1.6 to 3.5 mmHg, P<0.01), respectively. Central SBP and DBP decreased by 4 mmHg (95%CI 2.5 to 5.3, P<0.001) and 3 mmHg (95%CI: 1.6 to 3.5 mmHg, P<0.001), respectively. Heart rate did not change significantly with training.
- Distensibility did not change with training in the Ao-A (P=0.14) but increased by 9% in the Ao-P (P=0.009) and by 16% in de Ao-D (P=0.002). This change in distensibility was independent of the change in mean arterial pressure. β-stiffness did not change in the Ao-A (P=0.60) or Ao-P (P=0.08) but decreased by 6% in the Ao-D (P=0.04).
- Some of the observed increases in distensibility translated to a significant decrease in biological aortic age: by 3.9 years (95%CI 1.1 to 7.6 years, P=0.009) in the Ao-P and 4.0 years (95%CI 1.7 to 8.0 years, P=0.002) in the Ao-D. In the Ao-A, only a non-significant decrease was observed (1.5 years, 95%CI -0.9 to 5.4 years, P=0.16). When estimated based on β-stiffness, the biological aortic age was only significantly reduced in the Ao-D (3.2 years, 95% CI 0.1 to 6.2 years, P=0.04).
This prospective longitudinal cohort study in healthy participants showed that 6 months of training and completion of a first-time marathon resulted in reductions in blood pressure and aortic stiffness. The estimated biological aortic age based on observations in the Ao-P and Ao-D, calculated from the age-stiffness relationship at baseline and after completion of the marathon, was reduced by approximately 4 years after training.
In his editorial comment , Chirinos describes that age-related large artery stiffening (LAS) is caused by rupture of elastin fibers, deposition of collagen and calcium, vascular smooth muscle cell (VSMC) stiffening, and various other processes that reduce elasticity of the aortic wall. LAS is currently not addressed by pharmacological approaches and represents a high-priority therapeutic target, according to Chirinos.
Chirinos praises the sample size, advanced noninvasive imaging methods, assessments of pulsatile central hemodynamics and regional distensibility, and the unsupervised real-life training model of the study by Bhuva et al. Chirinos speculates about the involvement of exercise-induced blood flow on endothelial nitric oxide generation and a possible reduction in VSMC stiffness which may explain the reduced stiffness of the descending aorta (Ao-P and Ao-D) reported in this study. However, Chirinos states that other mechanisms may also be involved, and further studies about the mechanisms of exercise-induced reduction of aortic stiffness are necessary.
Sub-analysis showed that increasing age, male sex and slower running time were associated with greater benefit. However, the absence of a control group limits the conclusions that can be drawn from these findings. Furthermore, training for marathons does not only involve exercise but also other concomitant approaches, such as better sleep and dietary patterns. Marathon runners also tend to be health-conscious and adherent to training routines, which limits the generalizability of the findings.
Physical exercise remains underutilized and challenging to implement on a large scale in the general public as well as clinical populations. Chirinos states that there is a need for implementation research aimed at overcoming barriers for physical activity. While discrete periods of exercise training are beneficial, long-term physical activity across the lifespan, beginning at childhood, could have a much larger impact.