Left ventricular hypertrophyLVH

Left ventricular hypertrophy is thickening of the wall of the heart's main pumping chamber. It is an adaptation to increased workload, and whether it is benign or dangerous depends almost entirely on what caused it.

The pathological version is the common one. Chronically high blood pressure forces the ventricle to work against greater resistance, and it thickens in response, which is called concentric hypertrophy. That pattern is associated with heart failure, arrhythmia and increased cardiovascular mortality.

The athletic version is different in kind. Endurance training increases the volume of blood the heart handles rather than the pressure it works against, producing an enlarged chamber with proportionate wall thickening, called eccentric hypertrophy or athlete's heart. It is benign, associated with improved function, and it regresses when training stops.

Distinguishing the two matters clinically and is not always straightforward. Chamber size, wall thickness relative to that size, diastolic function, and whether the changes reverse with detraining are all used, and specialist sports cardiology exists partly for this question.

Heavy resistance training produces a pattern somewhere between the two, since it involves brief but large pressure loads, and the evidence suggests the changes are modest and not harmful in healthy people.

The genuinely important message is about the pathological form. It is usually silent, it is detected on an ECG or echocardiogram rather than felt, and the treatable cause behind most of it is high blood pressure.

In practice, that makes this an argument for knowing your blood pressure rather than for worrying about your training.