SINGAPORE - A 29-year-old man collapsed and died just 1km from the finish line while running a half-marathon on Sunday (Dec 4).

This is the second death at a Standard Chartered Marathon in Singapore, and one of several cases in different events.

In 2011, 22-year-old Malcolm Sng Wei Ren died after completing a half-marathon. Also in 2011, a 55-year-old man collapsed near the end of the 5km 100Plus Passion Run.

More recently, 45-year-old Martynn Koh Tong Yong, an avid runner, collapsed during the 2XU Compression Run in 2014. He later died in hospital.

Here are some tips on running a marathon safely:

1. Doctors advise that preparation is vital. This involves a proper training programme that includes resistance and flexibility training.

2. Runners must also wear the right shoes and must hydrate and refuel.

3. Those older than 35 or those with underlying risk factors - such as smokers, diabetics, and people with hypertension or with elevated cholesterol - should go for pre-participation screening.

4. Don't run marathons if you:

- Have not trained.

- Experience chest pains or discomfort while doing light exercises.

- Recently experienced a heart attack.

- Are a hereditary or stroke-induced heart attack sufferer (especially if you pale when exercising).

- Have high blood pressure and other heart diseases.

- Are diabetic, obese or very elderly.

However, doctors say that even people who exercise regularly run the risk of dying of heart failure during a marathon if they have a pre-existing heart condition that has not been detected.

Such conditions often manifest only when extra strain is put on the heart.

Even proper training may not be able to prevent a sudden cardiac death.