Overweight children are more likely to suffer fractures than normal-weight peers, then find themselves unable to exercise, a study suggests.
Obesity may lead to a cycle of misery
Those who are overweight are also more likely to suffer muscle and bone pain and other orthopaedic complications, the US research in Pediatrics found.
Obese and overweight adults are already known to have an increased risk of arthritis.
But a UK expert said overweight children should keep exercising.
The researchers from National Institutes of Health in Bethesda, Maryland reviewed medical charts from 227 overweight and 128 non-overweight children.
The overweight children were four and a half times more likely to have experienced some type of skeletal fracture than those who were a healthy weight.
The overweight children were also four times more likely to suffer from bone or muscle pain.
The most common type of musculoskeletal pain - knee pain - was seen in 6.6% of overweight children, compared to 2.3% of those of normal weight kids.
Overweight children also reported more mobility problems.
People of above normal weight generally have denser bones and are therefore have a lower risk of fracture.
But the team, led by Dr Jack Yanovski, said this may be offset by the greater force that results when an overweight child falls or braces themselves against an outstretched arm.
Writing in Pediatrics, they add: "Significantly overweight children and adolescents should be encouraged to engage in alternative modes of physical activity, such as bicycle riding or swimming, that potentially could alleviate the severity of lower extremity joint loading and discomfort."
But Dr Ian Campbell, from the organisation Weight Concern, said: "Obese children are more at risk of orthopaedic complications such as fractures.
"However that only occurs in a small minority.
"The vast majority of overweight children need to be exercising more to help them tackle their weight, as well as eating healthily.
"They should be encouraged to do whatever activity they want as that is the activity they will stick to and which they will still be doing in a year's time."