Cardiac arrest in a young person when they take strenuous exercise that tests the reserves of their heart is not unusual. Marathons have casualties and local papers report on footballers or cyclists who have had no obvious previous problem but who, apparently without any warning, collapse and die.

The most common causes in young adults are undetected abnormalities of the heart. A commonly inherited fault may be a cardiomyopathy, an enlarged heart that can either be inherited or result from an acquired disease. In footballers it is more likely to be an inherited problem as there might well have been other signs of intercurrent disease that their routine medicals would have detected.

In other cases, previously undetected valvular defects or congenital cardiac disabilities may be present but these, too, are usually picked up during medical tests. A liability to develop an abnormal rhythm of the heart during heavy exercise may cause an arrhythmia so that the chambers no longer beat in sequence and, like a car that is misfiring because of poor engine tuning, it may suddenly stall. Excessive alcohol increases the liability of a heart to develop arrhythmias.

A cause of sudden death in young people that can be overlooked is an undetected infection that has involved the heart muscle; for this reason people suffering from flu, a heavy cold or any other viral infection, should not take strenuous exercise. These patients could have myocarditis (inflammation of the heart) and they become a casualty.

There has been an increase in sudden death from cardiac failure and cardiac arrhythmias as the result of taking cocaine, cannabis and, less frequently, other drugs. This is more likely to be a problem in the world of music than on the football field. Lives of promise that met tragic endings

Marc-Vivien Foé

He fell to the ground unchallenged in the 72nd minute of a Confederations Cup semi-final against Colombia in Lyons in 2003. Medical staff are believed to have tried to restart his heart for 45 minutes but without success. Foé had played for West Ham United and Manchester City.

Reggie Lewis

Three months after he had collapsed in a game against the New Orleans Hornets, the Boston Celtics player died of a cardiomyopathy heart attack during a basketball game in 1993.

Miklós Fehér

Died while playing for Benfica against Vitória Guimarães in 2004. Doctors realised that he had suffered heart failure and performed CPR before an ambulance arrived. However, he was confirmed dead just before midnight after suffering from cardiac arrhythmia brought on by hypertrophic cardiomyopathy.

Sergei Grinkov

An Olympic and world figure skating champion, Grinkov collapsed and died from a heart attack in New York while he and his wife were practising for a performance in the 1995-1996 Stars on Ice tour.

Wilf Slack

The Middlesex batsman, who played in three Tests and two one-day internationals for England in 1986, died of a heart attack while batting in The Gambia in 1989, aged 34, after suffering blackouts over the previous couple of years, the cause of which remained a mystery. Words by Alex Penny