The body representing gyms and yoga studios says the next six months will be crucial in deciding how many stay open.
Exercise New Zealand had just surveyed its members and found numbers visiting since they were allowed to reopen in Alert Level 2 have been about 70 per cent of where they were prior to lockdown.
Exercise NZ cheif executive Richard Beddie said for most this did not equate to running a viable business.
"Anyone that's been made unemployed recently is very likely to cut back on what they might regard as disposable expenses. And for some, gym memberships will fall in to that category.
"So it's a bit too easy to say 'great we're re-opening, everything's fine'. It is very positive, which is good to see, but what we need to see in the long term is membership sales."
Beddie said the government needed to step in and help gyms meet the cost of the commercial rents they had to pay during lockdown, when they had no money coming in.
With a measured level of 750,000 New Zealanders attending a gym in pre-lockdown times, he said in terms of participation it was more popular than rugby, cricket and netball combined, and members deserved a slice of the $265 million promised to support sports clubs hit hard by the lockdown.