THE GYM with the longest opening hours in the city is nearly doubling in size.

The Underground Gym, in Portslade, is going from a 4,500 sq ft space to a 10,500 sq ft in the coming weeks.

The gym specialises in strength work, functional workouts and combat – with all abilities and fitness levels covered.

The gym is also increasing the number of classes it offers from 21 to 30 with high-intensity interval (HIT) training, boxing and strongman circuits.

The functional side of the centre involves activity like parkour, while the combat section has a full-sized boxing ring and top-end training equipment, including in kick-boxing and mixed martial arts.

Partner Alan McGuinness said: “We’re fairly specialised in what we do but specialised for everyone, including beginners, intermediates and experts.

“What we try and so is provide the whole package – including measuring up, meal plans and exercise plans - and we have some of the best people in the UK running our classes.

Also involved are head personal trainer Sol Gilbert and business partner Brandon Harris.