Now, a compound that may motivate you to work out harder

A team of Swiss researchers found that when a hormone in the brain, erythropoietin (Epo), was elevated in mice, they were more motivated to exercise.

In addition, the form of erythropoietin used in these experiments did not elevate red blood cell counts. Such a treatment has obvious benefits for a wide range of health problems ranging from Alzheimer's to obesity, including mental health disorders for which increased physical activity is known to improve symptoms.

"Here we show that Epo increases the motivation to exercise," Max Gassmann, a researcher involved in the work from the University of Zurich in Switzerland, said.

"Most probably, Epo has a general effect on a person's mood and might be used in patients suffering from depression and related diseases," he said.

To make this discovery, Gassmann and colleagues used three types of mice - those that received no treatment, those that were injected with human Epo, and those that were genetically modified to produce human Epo in the brain.

As compared with mice that did not have any increase in Epo, both mouse groups harbouring human Epo in the brain showed significantly higher running performance without increases in red blood cells.

"If you can't put exercise in a pill, then maybe you can put the motivation to exercise in a pill instead," Gerald Weissmann, Editor-in-Chief of The FASEB Journal, said.

"As more and more people become overweight and obese, we must attack the problem from all angles. Maybe the day will come when gyms are as easily found as fast food restaurants," he added.

The study has been published in the FASEB journal.