A cold-water bath might reduce muscle soreness after exercise but it is unclear whether there may be harmful side effects, researchers in Northern Ireland said. Researchers at the University of Ulster conducted a meta-analysis of 17 studies involving 366 people who used ice baths for several minutes after cycling, running or lifting weights. The analysis, published in the Cochrane Library, found compared to passive rest after exercise, a short bout of cold therapy reduced soreness by 20 percent, The New York Times reported. \"There was some evidence that cold-water immersion reduces muscle soreness at 24, 48, 72 and even at 96 hours after exercise compared with \'passive\' treatment,\" the researchers said in the study. However, the researchers said there has been little study of cold therapy versus active treatments, like compression sleeves or ibuprofen. In addition, ice-cold water could cause shock and increase heart rate -- side effects that should be studied over the long-term, the researchers added.