Icing sore muscles after a workout may cause more harm than good, suggests a new study published in the journal Sports Medicine.

Researchers in Ireland, at the universities of Ulster and Limerick, reviewed nearly three dozen earlier studies about how productive it is to ice sore muscles. They found that cold packs sufficiently numbed soreness – but that it also reduced muscle strength and coordination for up to 15 minutes after the icing stopped.

“The performance of athletes will probably be adversely affected should they return to activity immediately after cooling,” the authors said.

The cooling must slow nerve impulses in the muscle, researchers theorized, which negatively affects the muscle’s ability to work properly.

Returning to play after icing sore muscles – essentially with a numb area that could be masking a more serious injury – can actually lead to additional injury, said study leader Chris M. Bleakley, a research associate at the University of Ulster.

“Athletes should consider that pain is usually a sign that something is wrong with your body,” Dr. Bleakley said.