But while it's long been believed that endorphins （脑内啡）—chemicals in the body that cause happiness —are behind the so-called "runner's high”，a study suggested that there may be more to this phenomenon than we previously knew.
According to a recent study published by a.group of scientists from several German universities, a group of chemicals called endocannabinoids （内源性大麻素）may actually be responsible for this familiar great feeling.
To test this theory, the scientists turned to mice.
Both mice and humans release high levels, of endorphins and endocannabinoids after exercise along With many other chemicals. After exercising on running wheel, the mice seemed happy and relaxed and displayed no signs of anxiety.
But after being given a drug to block their endorphins, the mice's behavior didn't seem to change. However, when their endocannabinoids were blocked with a different drug, their runner' change. However, when their endocannabinoids were blocked with a different drug, their runner' high symptoms seemed to fade
"The long-held notion of endorphins being responsible for the runner's high is false Endorphins are effective pain relievers, but only when it comes to the pain in your body and muscle high symptoms seemed to fade.you feel after taking exercise," Patrick Lucas Austin wrote on science blog Lifehacker.
Similar studies are yet to be carried out on humans, but ifs already well known that exercise is a highly effective way to get rid of stress or anxiety.
The UK s National Health Service even prescribes （开药方）exercise to patients who are suffering from depression.
Being depressed can leave you feeling low in energy, which might put you off being more active. Regular exercise can cheer you up if you have depression, and ifs especially useful for people with mild to moderate （中等的）depression," it wrote on its website.
It seems like nothing can beat that feeling we get after a good workout, even if we don t fully understand where it comes from. At least if we're feeling down, we know that all we have to do is put on our running shoes.
61. What have scientists from German universities recently discovered?
A. The runner's high can be caused by endocannabinoids.
B. Working out is a highly effective way to treat depression.
C. Endorphins may contribute to one's high spirits after running.
D. The level of endorphins and endocannabinoids could affect a person's mood.
62. The scientists gave mice drugs in their experiments with the intention of .