Staff from Thetford-based Anglia Healthcare will compete at the Hercules Festival of Sport to raise money for Cancer Research UK.
Four members of Anglia Healthcare's team will take part, with Debbie Jones doing an open water swim, Andy Brunton a Duathlon, while Victoria Wright and Bill Jones will do a Sprint Triathlon.
Victoria Wright, a senior healthcare advisor at Anglia, said: "I run about 20 miles a week on average, and swim and cycle when I can too.
"I've been training hard to get my half marathon time down below two hours and I finished the last one in two hours one minute, so I'm getting pretty close!
"The Hercules event will push me further than ever before so I'll be glad to have my team of colleagues taking part alongside me."
Debbie Jones, founder of Anglia Healthcare, said "The Hercules Festival of Sport is recognised as one of the most challenging sporting events in the UK, so we are delighted to be taking part.
"Although we're a fit team, this will push us through some completely new pain barriers but it's all for a great cause.
"We're on track to hit our £500 target and we might even end up beating it. I wish the whole team the best of luck in rising to the challenge."
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