Anyone travelling from home for exercise if they do not need to is in breach of lockdown restrictions, a senior police officer has said.
Assistant Chief Constable Alan Todd said it was for officers to make judgement calls in individual cases.
He said the PSNI's interpretation of the regulations was supported by legal opinion.
It came as Arlene Foster said the executive would take a "step-by-step" approach to lifting lockdown measures.
Mrs Foster said the executive's chief scientific adviser advised that a second wave of the virus was likely.
ACC Todd said the legislation includes a necessity test.
'Breach of the regulations'
"You may not leave the place where you're living unless you have a reasonable excuse which includes the need," he told The Nolan Show on BBC Radio Ulster.
"For those people who can reasonably exercise either from their front door or close to it, and don't have a need to travel elsewhere to do that, then we believe that puts you in breach of the restrictions."
He added: "Officers on the ground will make a judgement on each case on his own merit."
ACC Todd said 206 fines had been issued for breaking the rules on social distancing, but only four relate to travel for exercise.
The number of hospital deaths in NI now stands at 158.
Later, Downing Street is expected to extend the lockdown in England for a further three weeks.
Wales, Scotland and Northern Ireland had already moved to keep the measures in place.
If and when the lockdown was lifted in Northern Ireland, it could not lead to a "total reopening", Mrs Foster told BBC's Good Morning Ulster programme.
"We know that the measures are working but we know social distancing will be with us for some time, and we will take a step-by-step approach to all of this," she said.
The first minister added that the executive was "planning for recovery" - especially for the economy, due to the impact that the virus was having on jobs and unemployment.
However, she would not be drawn on further detail about an exit strategy.
Mrs Foster also said she hoped that the Stormont Department of Health would move to put in place measures to allow people in NI to say goodbye to their loved ones.
On Wednesday the Health Secretary in Westminster, Matt Hancock, said new coronavirus guidelines in England would introduce steps to limit the risk of infection and allow goodbyes "wherever possible".
Mrs Foster said she had raised the matter with Stormont's Health Minister Robin Swann and that she expected him to make a decision on it shortly.
She added that the executive was continuing to discuss an expected list of essential workers and guidance for them, but that it was not due to be published soon.
The first minister said a paper had been drafted by a forum set up to advise the government, and that guidance it had produced on social distancing will need to be agreed by the executive first.