Nuffield Health has flexed its muscles with the acquisition of 35 Virgin Active gyms across the UK.
The sites, which include 10 in London, will open their doors today as Nuffield Health fitness and wellbeing centres.
The company will also take official ownership of the gyms today and will launch a multi-million pound rebranding programme.
In London, the branches will be based in Ealing, Enfield, Friern Barnet, Hendon, Islington, Colliers Wood, Wandsworth, Stockley Park, Croydon and Kingston.
Medical clinics will be built in a number of the gyms, providing services such as physiotherapy, in-depth health assessments, nutritional therapy and private GP appointments that can be used by both non-members and members.
Following the acquisition, Nuffield is now the second-biggest fitness provider in the UK by number of sites, behind Pure Gym, with 112 branches. All 2,300 former Virgin Active employees and 120,000 members have moved across to the Nuffield gyms.
Read more: Nuffield Health expands gym portfolio
It also operates 212 corporate fitness and wellbeing centres across the country.
"This marks an exciting milestone in our 59-year history and represents a significant next step in our strategy to provide a seamless and connected health and wellbeing offering to more people," Nuffield chief executive Steve Gray said.
"We will now be able to deliver much broader services such as physiotherapy, health assessments and nutritional therapy all under one roof, as well as provide our standard services such as fitness classes, personal training and swimming lessons. We can also offer a helpful link to our 31 Nuffield Health hospitals, with pay-as-you go treatment for all, without waiting lists."