Osteopaths have reported a 72% rise in the number of people suffering strain injuries due to overuse of their Wii or iPhone.
The British College of Osteopathic Medicine (BCOM) said experts at its London clinic had seen far more patients in the last week than before Christmas.
"The Christmas period is the obvious time, particularly this year's longer-than-usual break, when people spend more time entertaining themselves at home," said Manoj Mehta, head of clinic and osteopathy at the BCOM.
Although the BCOM declined to give the exact number of patients seen due to concerns about confidentiality, a spokeswoman said it was not small.
Mr Mehta said people presume there is no need to warm up when using the Wii, adding that anyone suffering strain should perform gentle stretching exercises and not over-exert themselves if playing sports games, such as tennis.
Over-using the iPhone can also cause problems, he added.
Neck ache and headaches can be caused by prolonged periods on the phone, particularly when playing games or using apps.
Gentle stretching exercises for the neck, upper back and shoulders can offer relief but people should avoid long periods on the phone, he said.
He added: "Do not ignore the warning signs - the twinges that occur whilst you're playing these games serve as a warning.
"It is important that, if the ache or pain does not ease off after gentle stretching, the person seeks the advice of a GP or osteopath."