Is the treadmill free?
'Tapis roulant' is borrowed from French. Italians say 'ta-PI roo-LAN'. 'Libero' = LEE-be-ro.
Ask this when approaching a treadmill that appears unoccupied but may have a water bottle or towel on it indicating someone is using it.
'Libero' in this context means 'free/available', not 'free of charge'. The same word applies to other equipment: 'La cyclette è libera?' (Is the exercise bike free?). Note the gender agreement: 'il tapis roulant è libero' (masculine), 'la macchina è libera' (feminine).
Posso usare questo tapis roulant?
Can I use this treadmill?
Direct request.
Stai usando questo?
Are you using this?
Very casual, informal.
C'è un tapis roulant libero?
Is there a free treadmill?
When all appear occupied.
In Italian gyms, leaving a water bottle or towel on a machine to 'reserve' it while doing other exercises is common but sometimes frowned upon. A polite note ('Torno subito' — 'Back in a moment') is sometimes left, but this varies by gym culture.