Two functional fitness franchises are continuing their legal battle over a dispute relating to patents.

In August, Body Fit Training (BFT) filed a lawsuit in the US District Court in California against F45 Training in an attempt to invalidate two of its existing patents.

In retaliation, F45 has now began legal proceedings in the state of Delaware, declaring that BFT infringes one of its patents.

The lawsuits between the two Australia-based companies are part of an ongoing global dispute over business strategies and the use of technology.

It began in late 2019, when F45 filed a lawsuit in the Australian Federal Court against BFT over an alleged patent infringement, aiming to protect the way it manages its franchises through a central computer system.

Following the latest round of legal proceedings, BFT's joint CEOs Cameron Falloon and Richard Burnet issued a strongly-worded statement, saying that: “The US lawsuit we filed is part of BFT’s global strategy to defeat F45’s improper efforts to assert invalid patents to try and hinder our ability, and the ability of our franchisees, to advance what we believe to be a superior business model and approach to fitness training."

They added: "We believe we have the upper hand in similar litigation in Australia. As a result, we are confident that, whether the US litigation moves forward in California or Delaware, we will ultimately prevail in both the courts and in the global marketplace.

"We see the United States as an important next step in our global expansion and even though we are a much smaller company, we do not intend to let F45 or any competitor push us out of the marketplace."

Launched in 2018, BFT has sold 150 franchises across Australia, New Zealand, Singapore and the US.

F45 Training has a presence in more than 50 countries with more than 1,900 franchises sold.

In June, F45 revealed plans to take the company public and list on the US market NASDAQ.

The listing is planned to take place through a merger with special purpose acquisition company Crescent Acquisition Corp, with initial estimates valuing F45 at around US$845m.

Speaking at the time the plans to go public were announced, F45 CEO Adam Gilchrist said: "F45’s mission is to improve people’s lives and wellbeing, and the company was founded to make unique, effective and high-quality training accessible to everyone, while empowering franchisees to run successful businesses.

“As a public company, I am confident that we will be able to accelerate our mission, while creating value for our shareholders.

"We look forward to continuing to disrupt our industry and to inspire even more people to achieve their health and fitness goals through F45’s innovative workouts combined with our nutrition programme.”