Masks, which when worn correctly are highly effective in reducing transmission, are already compulsory in indoor public places in the UK. There is talk of making them mandatory in some outdoor settings, like in Spain.
Perhaps the UK should follow France and require people jogging or cycling to wear masks if they are unable to maintain a physical distance from pedestrians.
There are many arguments against such a measure. The risk of transmitting COVID-19 outdoors is an order of magnitude less than indoors, according to a study yet to be published in a scientific journal.
Exercising outdoors is one of the few freedoms people in England still have. When jogging or cycling, contacts tend to be rare and fleeting, so would not meet the UK’s official definition of a “close contact” for which one needs to spend 15 minutes closer than two meters – though this time period can now be notched up in a series of shorter encounters throughout a day.