Sport England’s annual Active Lives Survey of 1,058 people in the area in the year to November 2020, found just 75% walked for 10 minutes at least once a month for any reason – down from 83% the year before.
The proportion who walked for leisure once a month also fell from 73% to 70% and the number of people walking to commute, visit a friend, or going to a shop fell significantly from 40% to 33%.
It also emerged that only 11% rode a bike at least once every four weeks – down from 14% the year before.
Sport England say a huge fall in walking for travel nationally shows the "unprecedented" impact of the pandemic.
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Lisa O’Keefe, director of insight at Sport England, said: “This reflects anxiety about going out and catching or spreading the virus, more responsibilities at home and lack of access to private outdoor space.”
Stephen Edwards, interim chief executive of the organisation, said: "It’s incredibly important that we keep active. Just a 20-minute walk can prevent long-term health conditions like type 2 diabetes, heart disease, and depression."
Rachel White, head of public affairs at cycling charity Sustrans, called for local authorities to invest in infrastructure for everyday trips to make it easier for people to leave the car at home.
She added: "We must enable people to use their cars less and travel actively more often, for the benefit of our own health and the future of the planet.”