They have to carry their backpack and if they forget it, they forget it - because there's just too much to keep track of.

They are much cheaper than other taxis, although the lone passenger can only carry a backpack as luggage.

But think about it: when was the last time you saw anyone carrying a backpack and smiling at the same time?

For much of the time he and fellow commandos carried a backpack weighing up to 85lb.

I'm also carrying a backpack filled with 100kg (15 stone 10lb) of sand and lead, to represent the weight of carrying a battle casualty.

Wear a weighted vest or a heavy backpack and walk for 30 minutes at a steady pace.

Hills look steeper and targets look farther away when wearing a heavy backpack.

You have nothing to lose but your heavy backpacks.

Any frontman who turns up at a gig wearing a backpack doesn't deserve to be on stage.

To his schoolfriends he was a 'brainiac' — a quiet, clever, geeky student who wore a backpack to class and spent his summer holidays studying biotechnology.

Almost as bad are passengers who insist on wearing their backpacks.

For added resistance, weights can be added by use of a dip belt, weighted vest, or by wearing a backpack with weights in it.

She was fully clothed and still wearing her backpack.