Task: Question Answering
Input (English): Background Paragraph: Sometimes muscles and tendons get injured when a person starts doing an activity before they have warmed up properly. A warm up is a slow increase in the intensity of a physical activity that prepares muscles for an activity. Warming up increases the blood flow to the muscles and increases the heart rate. Warmed-up muscles and tendons are less likely to get injured. For example, before running or playing soccer, a person might jog slowly to warm muscles and increase their heart rate. Even elite athletes need to warm up ( Figure below ). 
Story: Greg and Carl and about to do a marathon. Greg sees Carl doing some warm ups and laughs to himself and thinks it is silly. They both want to get a good time, and are both avid runners. 
Question: Does Greg's lack of a warm up cause an increase or decrease in the likely hood of an injury?
Output (English): increase.