But the men and women of Cosham and Southsea fire stations did not need any mountaineering skills.

Instead they took on the challenge on step machines at Cascades shopping centre, Portsmouth.

Shoppers looked on as the firefighters made their 'ascent' in 20-minute shifts on the gym machines in their full uniform, including weighty breathing apparatus on their backs.

Saturday's fundraising feat was organised by Southsea firefighter Tim Debens to raise money for the Firefighters Charity and Hampshire-based Naomi House Children's Hospice.

Tim, 28, is due to take part in a sponsored climb of Mount Kilimanjaro in Tanzania in January with a group of firefighters from across the country.

He said: 'We obviously need to keep our physical fitness up and something like stepping is a good idea anyway because it simulates something we do in the job.

'I kicked off this morning when it was a bit quieter and it's hard work – if you do half-an-hour in all the kit you do know about it.'

He added: 'It's two really worthwhile charities we're doing it for.

'Whatever we can do to help – especially in the local community – we'll try to do it.'

Scott Yule, 33, a firefighter at Southsea fire station, was among those stepping up to the task at hand.

He said: 'It's tough work but we use the stepping machines in our cross-training with the rowing machines and exercise bikes.

'Tim is doing the Kilimanjaro climb in January and this was a good idea of his. He asked me to help out.

'I was more than happy to raise money for two really worthy causes.'

The firefighters hope their efforts will have raised £1,500 for the Firefighters Charity, which supports serving and retired fire service personnel and their families, and Naomi House Children's Hospice based near Winchester, which provides hospice and respite care for terminally-ill children and their families.

» For more information about the charities, visit firefighterscharity.org.uk and naomihouse.org.uk