Children’s activity levels have plummeted since the start of the Covid pandemic, with one in three doing less than half an hour’s exercise a day, official data reveals.
Experts said repeated lockdowns and social distancing restrictions meant rising numbers of young people had barely left their homes for long periods.
It follows warnings that the system of bubbles in schools has killed off much competitive sport and seen sports days axed.
The figures from Sport England show that in the academic year 2019/20 – which took in the first lockdown, when schools were closed – 31.3 per cent of children did less than 30 minutes of activity or exercise daily.
In total, 2.3 million children fell into the least active category – a rise of more than 200,000 on the previous year, when 28.9 per cent of young people fell into that category.
Government advice recommends that children get an hour’s exercise daily, but less than half of children managed this, with just 44.9 per cent meeting the guideline – down from 46.8 per cent 12 months before.
Children and young people's activity levels
Fitness experts have called for greater access to sports facilities this summer in a bid to boost activity levels and tackle Britain’s obesity crisis. One in 10 children is obese by the time they start primary school, rising to one in five by the time they leave.
The Telegraph is campaigning for ministers to put children first, with swift action to bring an end to the disruption to schools and restore a normal school day.
Experts have warned that the bubble system, which limits children to class groups, has badly damaged competitive sport.
Earlier this week, Dame Rachel de Souza, the Children’s Commissioner for England, called for a "summer of fun", urging schools to throw open their doors so children could embrace drama, sport and social activities.
She also called on ministers to abolish systems of bubbles and self-isolation as soon as possible, saying urgent action was needed to help get children "back to normal".
Almost 40 per cent of sports facilities in England are behind school gates, and most cannot be accessed during school holidays.
Tim Hollingsworth, Sport England’s chief executive, said: "The pandemic has caused widespread disruption to the activity habits of our children and young people. School plays a significant role in helping our children to play sport and to be active, and the disruption to schooling has definitely contributed to a decline in activity levels."
Children’s activity by year group
He said the situation would have been even worse if not for a "monumental effort" by parents, schools, and clubs to try to keep children playing sport.
Mr Hollingsworth added: "As we return to some sort of normality, children and young people must be at the front of our thinking," calling for a longer-term strategy to boost sport and PE in schools.
Before the pandemic, research showed that children are far less active during the summer holidays than term-time, with fitness gains achieved during the school year wiped out in six weeks.
Research on more than 400 children found that, during the academic year, pupils made steady improvements in their fitness levels. But around 80 per cent of gains were reversed during lazy summer holidays, in which PE lessons and walks to school were replaced by days hunched over gadgets.
Earlier this year, fitness experts urged ministers to overhaul national strategies on sport and recreation, saying children would be more likely to get active if they were offered the chance to try rollerblading or "free running" rather than being restricted to traditional sports.
In November, Telegraph Sport launched a "Keep Kids Active" campaign amid growing concern about a mental and physical health timebomb as activity levels plunged among under-18s.
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Children physical health lockdown form