GYM Group tumbled 14.4pc, or 17p, to 101p after it warned of a tough year ahead.
The company, which owns 230 gyms, said memberships rose 14.3pc to 821,000 in 2022.
But in the first two months of this year, the sign-up rate was slower than in the same period last year.
It expects to open 12 gyms this year. This would fall short of the 28 sites it opened in 2022. Energy costs are also expected to be around £10m higher this year compared to last year.