A smile will improve your run, research finds

A study finds that runners used less energy while smiling. Participants were 2.8% more economical when smiling than frowning.

Physiological factors include cardiovascular fitness, and how efficient an athlete is at using energy (their "movement economy"). A critical psychological factor, on the other hand, is perceived effort, or how hard we feel we are working during an activity. The lower our perceived effort, the easier we feel that an activity is.Crucially, any strategy that reduces how much an athlete perceives i...