One of England's highest ranking police officers has called on government ministers to clearly define the maximum distance people are allowed to travel to undertake their daily exercise, in a move that could impact the way personal trainers are operating under England's lockdown restrictions.

Personal training is allowed to continue during the latest restrictive measures, as long as it is undertaken on a one-on-one basis in a public outdoor setting – such as a park – and social distancing measures are in place. The sharing of equipment is not allowed.

The move to tighten the law follows a number of episodes where the police have been wrongfooted during attempts to fine people for exercising.

The most high-profile case saw two women being fined £200 each for driving five miles to take a walk at a beauty spot in Derbyshire.

The case caused further confusion after health secretary Matt Hancock backed the police action, only for Derbyshire's chief constable, Rachel Swann, to say the fines had been withdrawn and that the police had "apologised for any concern caused".

Writing in The Times, Dame Cressida Dick, commissioner of the Metropolitan Police in London, said ministers should introduce limits similar to those imposed in Scotland and Wales, where strict restrictions apply on how far people can travel for exercise.

Current guidance on travelling to exercise in England is somewhat vague, as it only stipulates that the public "can leave the home to exercise" and that they "should not travel outside their local area".

There is, however, no detail on what "local area" means.

Having clearly defined distances allowed for exercise-related travel could help personal trainers and their clients identify possible venues for training sessions – and ensure they aren't in danger of being fined. However, it could also restrict the areas within which personal trainers were able to operate.

It's thought such restrictions would also be almost impossible to enforce.

HCM editor, Liz Terry, said: "Distance to exercise is a spurious measure at a time when keeping fit and healthy must be top of the agenda for everyone.

"Social distancing and safety must be the two main priorities and if people are finding that the areas where they live are crowded with walkers, runners and cyclists, it makes sense for them to travel a little further afield to find somewhere to exercise where it is possible to socially distance.

"We urge the government not to impose standard distance-related boundaries, as this would interfere with the valuable work being done by PTs and would also discriminate against people who live in built-up areas or places with high population densities."

• For more information (and confirmation of the legality of) personal training during lockdown, please visit the latest advice from Sport England by clicking here..