Gyms are being reminded that any facility running outdoor classes must limit numbers to four.
That is the advice from Ireland Active, which represents the industry, during phase one of restrictions being lifted.
It follows evidence that outdoor fitness classes are taking place in groups of more than four today.
Ireland Active says social distancing must be observed, gyms should ensure people pre-book a space, and people cannot access the facility to use changing rooms or toilets.
It says no physical contact may take place and if equipment is being used it must not be shared.
Ireland began the first day of its phase one lockdown exit today and Government officials are reminding the public to observe social distancing and remain vigilant.
Speaking today, Assistant-Secretary General in the Department of the Taoiseach Liz Canavan said: "It’s really important that we are disciplined in keeping to the measures specified.
“Our ability to move through the phases will depend on sticking with it. Indeed, as I said last week, many of these habits will have to become the norm for us for some time.
“It is permitted to exercise in the outdoors within five kilometres of your home. It is critical in this that you continue to observe social distancing while exercising.”