Online shopping is ruining people's muscles as they fail to carry home their own groceries, physiotherapists say.
While shopping on the internet offers much-wanted convenience, it is stripping people of muscle-strengthening exercises that help keep them healthy into older age, according to the Chartered Society of Physiotherapy.
Its poll of more than 2,000 people found 24% of those aged 65 and over do no strengthening activities at all each week.
This puts them at increasing risk of falls and other health problems, the society says.
NHS guidelines suggest people do two strengthening sessions a week, such as exercising with weights, or lifting and carrying heavy loads such as groceries.
For people aged 65 and over, the sessions can also include activities that involve stepping and jumping, such as dancing.
Professor Karen Middleton, chief executive of the Chartered Society of Physiotherapy, said: "Online shopping may be very convenient but it does mean that we are losing some of the methods that used to exist for strengthening our muscles.
"We're carrying fewer bags home from the supermarket because it arrives at our door.
"We're also waiting at home for other goods to be delivered when in the past we would have gone out to buy them.
"This isn't an argument against progress. It's just to show that maintaining strength and being active doesn't have to mean going to the gym, and we should look for ways to build it into our everyday lives."
She said people should not think that becoming weaker and frailer was an inevitable part of getting older.
"As the guidelines set out, it doesn't mean immediately hitting the gym to lift weights. To start, it can be digging in the garden or simple body-weight exercises like standing up out of a chair 10 times.
"There are easy ways to do it but the essential thing is to get started and these poll results show a lot of work needs to be done to get that message out."