St John's workload has risen more than 8 per cent in the Bay - more than double the national average - and 30 more volunteers are needed.
The Bay's surging population has put the pressure on St John with new figures showing call-outs had also jumped from 14,924 in 2012-2013 to 16,143 in 2013-2014 - a rise of 8.2 per cent
St John Western Bay territory manager Ross Clarke said the growth was "staggering" and there was no sign of the increase slowing down.
"The numbers signify the growth in the area with people coming in and a bit of an aging population as well. It will definitely get busier and busier," he told the Bay of Plenty Times Weekend.
Call-outs are classified according to their urgency and one classification at the lower end recorded the biggest lift, up from 1339 in 2012-2013 to 3415 in 2013-2014. Those calls were less life threatening and could range from abdominal pains to collapses and isolated limb injuries.
Improved technology and better triage systems used to prioritise emergencies may have accounted for some of the spike, he said.
"There are medically trained staff overseeing the calls to make sure we send the right response. Once upon a time it may have been graded as a higher acuity job and more life threatening than it was."
The number of traffic incidents that required St John rose to 490 from 477 for the same time period.
St John needed 574 volunteer hours at its stations in Tauranga, Mount Maunganui, Te Puke, Katikati and Omokoroa each week.
It had 110 volunteers but another 30 were needed despite the Western Bay recruiting an extra eight front line paid staff earlier this month, Mr Clarke said.
"We always need people coming in because there is a turnover. But the exciting thing is people from all walks of life join because they want to give back to the community, it's amazing."
Often it was a good way to "shake up your life," he said.
Mother-of-three Melissa Bradshaw, 29, had wanted to join St John since she was 14.
Being able to help someone else was rewarding, she said.
"A lot of people that ring up apologise that they have actually phoned because they don't want to be a nuisance. But that is what we are there for, to go out and help them even if they have fallen out of bed and can't get back in, especially the elderly."
Her biggest supporters were her children, she said.
"My kids love it and they think mum is a role model."