Performance

Sochi's elevation makes speed-skating world records unlikely.

Less than eight percent of Bolt's energy contributed to his motion during the 100 meters at the 2009 World Championships.

Researchers study movement to help improve the quality of artistic performances.

David Rudisha's world record 800-meter performance, and a look ahead to the women's final.

Analysis suggests the likelihood of future world-record-breaking performances.

Research shows that the answers to a sleepiness questionnaire can predict how long an athlete will remain on his team.

Optometrists say that games played on bright, sunny days can make hitting difficult for light-sensitive players.

From reality TV to dance class, dance is more than pirouettes and plies.