# The Impact of Skinsuit Zigzag Tape Turbulators on Speed Skating Performance
## 5 The Impact of the Zigzag Strips on Skating Performance in a Real Skating Environment
### Analysis of Historical World Record Data  
#### 5.3.1 Results for 5000 m  
Figure 10 presents a historical overview of the improvements of the world record on the men's 5000 m since 1972. Depicted is the improvement in seconds with respect to the previous record, starting with the 1972 world record of [PERSON] in Inzell, a German medium-altitude (690 m.) outdoors skating rink. The figure shows a top seven of improvements better than 4 s. Clearly visible are the records set at the 1691 m altitude Medeo natural ice rink in Almaty, Kazachstan, with its sometimes favorable wind. Two others were set by [PERSON], one showing the advantage of the clap skates introduced in the season 1996-1997 and one with both the clap skates and the zigzag strips \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Ranking** & & & & **Seconds behind [PERSON] in** & \\ \hline
**Calgary** & **Name** & **Country** & **Heerenveen** & **Nagano** & **Calgary** \\ \hline
1 & [PERSON] & NED & 0 & 0 * & 0 * \\
2 & [PERSON] & NED & 5.3 & 6 * & 4 * \\
3 & [PERSON] & BEL & - & 6.1 * & 6.1 * \\
4 & [PERSON] & NOR & 6.8 & 17.5 & 7.4 * \\
5 & [PERSON] & NED & 3 & 9.2 * & 8.1 * \\
6 & [PERSON] & GER & 7.9 & 12 & 8.6 * \\
7 & [PERSON] & ITA & 11.1 & 15.9 & 9.1 * \\
8 & [PERSON] & CAN & 18.6 & 26.5 & 11.3 * \\ \hline \hline \end{tabular}  
* With zigzag strips.  
\end{table} 
Table 5: Differences with [PERSON] of a number of elite skaters at three consecutive 5000 m races. including the advantage of the low ambient pressure during the Olympic race. The record of [PERSON] might be associated with the introduction of the Nike Swift skinsuit at the 2002 Salt Lake City Winter Olympics. The improvement of [PERSON] is the second largest since the beginning of the 20 th century, only topped by [PERSON], in 1955, who skated at the Medeo magic oval (18.1 s). In Figure 11, all of these incremental changes are put together, again with the starting point in 1972. The coordinates for the horizontal axis were computed according to the dates the records were skated: 15 February 1995 is 1995.126. The graph nicely depicts the development of the men's 5000 m world record during the last four decades. Over the years, many factors have contributed to higher skating speeds--some in a gradual way, like improvements in nutrition, training methods (better understanding of the skating technique) and medical support; some in a small jump, such as the creection of indoor skating rinks and the associated ice preparation; and others in a more abrupt way, such as innovations in skates and suits. If specific performance improvements follow an S-curve, Figure 11 can be seen as the sum of a continuous stream of S-curves with smaller or larger jumps on top of a generally increasing curve associated with learning and societal wellbeing. An abrupt change is clearly visible around 1976 and might be associated with the introduction of the skinsuit one year earlier. By 1976, all the skaters wore the tightly fitting Lycra suit, and, over one year (including the Olympic Games of Innsbruck), lap times improved with an average of 0.52 s. The increase in speed around 1987 can be traced back to the opening of the indoor rinks of Heerenveen and Calgary. The average improvement of the world record in the 10 years prior to the introduction of the clap skate in 1996/97 is 1.601 s per year (R\({}^{2}\) = 0.935), or 0.128 s per lap per year. In the ten years after the introduction of the zigzag strips on the suit, 1998-2008, the average improvement slightly increased to 1.638 s per year (R\({}^{2}\) = 0.965), resulting in a 0.131 s per year decrease in lap time, albeit that the level is more than 8 s higher than before. After [PERSON] set the record on conventional skates during the Olympic Games in Hamar, Norway, it took about 3.5 years until the introduction of the clap skate before the record was broken again. Such long periods usually occur when innovations have reached the end of their development curve.