Circulation 2017; 136(2):138–48

It is well recognised that physical activity is associated with a lower risk of cardiovascular events but what actually happens within the coronary arteries of those who regularly exercise?

This study used CT to assess coronary artery calcification (CAC) and plaque characteristics in 284 middle-aged asymptomatic men engaging in sport. The participants had no history of cardiovascular disease and gave lifelong exercise history grouped as <1000, 1000–2000 or >2000 MET-min/week.

Surprisingly, the most active group had approximately 50% higher prevalence of CAC and burden of atherosclerotic plaques. Reassuringly, these plaques were 3.5 times more likely to be stable and less likely to rupture compared with unstable non-calcified plaques with fibrous caps and necrotic cores that are most vulnerable to rupture and cause an ischaemic event. Those engaging <2000 MET-min/week had no statistically significant increase in CAC.

The clinical relevance of CAC in the most active athletes remains unclear. We need to investigate coronary physiology in sport further. So while we harden up in more ways than one while preparing for that marathon, it seems these changes …