Body monitors have been introduced for trainee Royal Marines Commandos to try to prevent death or serious injury during extreme training.

The technology is "helping to eliminate the risk of potentially fatal heat illness," the Royal Navy said.

The kit records trainees' physiological data, which trained instructors then study. So far, more than 200 recruits have used the technology.

The Royal Navy said it had already saved one person's life.

First used in the spring, it had also prevented two very serious casualties at Commando Training Centre Royal Marines at Lympstone, near Exeter, the Royal Navy added.

The monitor, known as Open Body Area Network (OBAN), records key features as a trainee tackles activities, such as a "nine-mile speed march" or "gruelling 30-miler".

It provides data including heart rate and skin temperature, and predicts the person's estimated core temperature.

Early recognition of exertional heat illness is key to allowing effective cooling as soon as possible, the Royal Navy said.

If untreated, heat stroke can lead to multiple organ failure, permanent disability or in the worst cases loss of life.

When heat stroke occurs, the goal is to reduce the core body temperature to below 39.5°C within 30 minutes to limit damage to the body's cells.

Maj Erik Nielsen said: "Royal Marines' training is arduous. It pushes people to their physiological limits but no-one should die in training from heat illness.

"We do not want to lose anyone and, therefore, process and education is paramount."

Sports medical doctor of the Royal Marines, Dr Ross Hemingway, described the technology as "exciting and cutting edge".

"We are much better educated, prepared and trained to deal with heat illnesses than we were five to six years ago," he added.

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