Background: 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 ).

Situation: Steve and Jon are getting ready for a big marathon that both have been training for. Steve gets ready for the race by stretching and doing some pre-race warm ups. Jon on the other had does no think warming up helps at all, and decides to just remain seated until it is time for the race to start.

Question: Who is more likely to get an injury during the race?
Answer: Jon

Situation: Steve and Jon are getting ready for a big marathon that both have been training for. Steve gets ready for the race by stretching and doing some pre-race warm ups. Jon on the other had does no think warming up helps at all, and decides to just remain seated until it is time for the race to start.

Question: Who is less likely to get an injury during the race?
Answer: Steve

Situation: Steve and Jon are getting ready for a big marathon that both have been training for. Steve gets ready for the race by stretching and doing some pre-race warm ups. Jon on the other had does no think warming up helps at all, and decides to just remain seated until it is time for the race to start.

Question: Is Jon more or less likely to experience an injury than Steve during the race?
Answer: more

Situation: Steve and Jon are getting ready for a big marathon that both have been training for. Steve gets ready for the race by stretching and doing some pre-race warm ups. Jon on the other had does no think warming up helps at all, and decides to just remain seated until it is time for the race to start.

Question: Is Steve more or less likely to experience an injury than Jon during the race?
Answer: less

Situation: 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: Who is more likely to get an injury during the race?
Answer: Greg

Situation: 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: Who is less likely to get an injury during the race?
Answer: Carl

Situation: 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 Carl's warm up cause an increase or decrease in the likely hood of an injury?
Answer: decrease

Situation: 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?
Answer: increase

Situation: 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 Carl have a higher or lower chance of injury than Greg?
Answer: lower

Situation: 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 have a higher or lower chance of injury than Carl?
Answer: higher