Background:Liu Hong, who won gold medal in the women 20 kilometer Race walking event at the 2015 World Athletics Championships in Beijing with the time of 1:27:45, received 5 yellow
paddles for loss of contact. Lu Xiuzhi, the silver medal winner with the same time, received 4 yellow paddles and 1 Red Card for loss of contact. Lyudmyla Olyanovska won the Bronze Medal with time of
1:28:13 without any of yellow paddles or red Cards.
Methods: The circuit is 1km. the video was recorded by two high speed digital cameras CASIO EX-FH25 in National Stadium. The data was measured at the height of 1m and distance of 12m.
The main axis angle between the two aircraft is nearly 60 ° and the frequency is120 frames/ sec. Data was analyzed by APAS kinematics system and smoothed with a 7Hz digital filter.
Results: Liu Hong received the first yellow paddle on the seventh kilometer, the medalist competitor make a progression acceleration steps of speed on the former 6 kilometer. The lap
time is 4:18 first shorter than the average lap time at sixth kilometer (4:23). By four of five yellow paddles, the race walking speed (4:21, 4:23, 4:12 and 4:19) of Liu Hong is faster than average
speed (4:23). These demonstrated that high Competitive speed is factory leading to violate Rule for loss of contact.
The index of Liu Hong is positive correlation before 7th kilometers. Speed of Liu Hong was increased from 4:34 of first kilometer to 4:18 of sixth kilometer. By this procedure her stride length was
increased from 1.06 m to 1.09 m. by the yellow paddles this correlation was unrhymed, especially on the final 5th kilometers the speed is 4:11, but the stride length is only 1.08 m. The average stride
length of Liu Hong is 1.08 m, which is shorter than Lu Xiuzhi (1.09 m) and Lyudmyla Olyanovska (1.12 m), although the height of Lu Xiuzhi (1.54 m) is 0.02 m shorter than Liu Hong (1.56 m). Liu Hong’
stride length by three yellow paddles is 1.07 m. It is obviously that her stride length is too shorter to complying with thedefinition of Race Walking under IAAF Rule.
The stride length of Liu Hong by two yellow paddles is 1.09 m, which was her minimum(101.7°) and Vice-minimum(103.9°) Knee Angle on Vertical upright position. Hers leg so unloosened that her Knee
Angle is too small.
Head Fluctuation Length of Liu Hong is 0.12 m, which was longer than Lu Xiuzhi (0.10 m). Although Head Fluctuation Length of Lyudmyla Olyanovska was 0.12 m, the same as Liu Hong, but her height (1.66
m) is 0.10 m higher and her stride length is 0.04 m longer than Liu Hong. By four of Liu Hong’ five yellow paddles, the race walking Head Fluctuation Length is 0.13 m, which is equal to Lu Xiuzhi’
Maximum Head Fluctuation Length, by this length Lu Xiuzhi was showed one yellow paddle, too. one of Liu Hong yellow paddles race walking Head Fluctuation Length is 0.14 m, The Head Fluctuation Length
of Liu Hong is too lager to complying with Race Walking definition
Conclusions: Short stride length by high speed is factory leading to violate Rule for loss of contact of Liu Hong.
Small Angle Knee on Vertical upright position and lager Head Fluctuation Length of Liu Hong was easy to be disqualified athlete.