A study of Irish teenage boys with low fitness levels has found that they spend an average of two-thirds of their day sitting down and 85% already have high blood pressure.

The study was carried out by researchers at Dublin City University (DCU) and it involved 82 boys in transition year. Its findings were highlighted at the launch of the 2016 Schools' Fitness Challenge, which aims to encourage secondary school students nationwide to try to improve their fitness levels.

Launching the event, Prof Niall Moyna, head of the School of Health and Human Performance at DCU, expressed concern about the study's findings.

"Previously we have seen studies that show increased risk factors of heart disease for ‘low fit' children, but we now know students actually already have heart disease at just 15 years of age.

"Every school around the country has unfit children, but the good news is that every school has a free lifestyle drug that can cure it - exercise. Today we are asking PE teachers and their students to get involved with this fitness challenge to encourage healthy behaviours," he said.

The Schools' Fitness Challenge is being run by Irish Life Health and it involves simple steps, which can improve fitness levels in just six weeks.

"Being active is not just for those students who consider themselves ‘sporty', or who are part of a sports team. Being active has great benefits both to mental and physical wellbeing, and the Schools' Fitness Challenge is a great way to take small steps to leading a more active lifestyle," commented Cork camogie player, Ashling Thompson, at the launch.

Registration is now open and PE teachers are being urged to sign up their students for the six-week fitness challenge. It is open to all secondary school students nationwide.

This marks the fifth annual Schools' Fitness Challenge and some 60,000 students have taken part in previous years.

PE teachers are asked to register for the challenge here by 5pm on September 30.