I take excersize at night with a group of eight~ other ladies. the lesson takes place in a kupat cholim office located in a shopping center. The ;esson takes place between 9-10PM. the shopping center closes at 10PM. The problem is that the kupat cholim is locked at that hour (The cleaning man opens it at the hour so we can come in for the class) and the cleaning person is an arab man. He is in the kupat cholim alone, locked in with us,t he ladies of the excersize course. Is there a problem of Yichud in this situation? one can leave whenever one wnats to but the door is locked fromt he outside. Thank You.
There is no prohibition of yichud with a large group of women. In addition the exercise presumably takes place in a separate room behind a closed door, where the cleaning man is not permitted to enter, which also diminishes the concern of Yichud.
Shulchan Aruch, Even Haezer, Rama 22:5, Bais Shmuel s”k 11