Figure 4.

Relationship between tangential acceleration and centripetal acceleration for data collected from horses racing (red circles, 165 horses, 24 333 samples) and polo games (blue circles, 17 horses 8512 samples). During turning in polo games, horses were able to change horizontal speed while changing heading. During racing, the horses are dominantly experiencing centripetal acceleration during the turns, and they only accelerate again when the centripetal acceleration is small. Most data lie within the black circles, which are defined by the friction limit model with a static coefficient of friction of 0.6 and 0.7, respectively. The larger the static coefficient friction, the larger is the radius of the black line.