Wednesday, April 1, 2009

Understanding Gold Medal Standards

Selection – Understanding Gold Medal Standards
By Tom Landry,
Nova Scotia Rowing Association

What is a Gold Medal Standard?
A Gold Medal Standard (GMS) is the theoretically predicted fastest possible time that a crew of a particular class can race the Olympic distance of 2000 m.

In Canada, The GMS times are developed by Rowing Canada Aviron (RCA) (often the Director of High Performance) based on gold medaling international performances. The GMS times are reflective of what RCA deems a necessary time for a crew to win a gold medal internationally (World Championships and Olympic Games). As international race times improve, GMS times change to reflect advances in training, equipment, and competitiveness. Therefore, the GMS times published by RCA are adjusted often on a four year basis to coincide with the Olympic quadrennial.

Understanding Gold Medal Standards
Currently (2008), The GMS time for a Heavyweight Men’s 8+ is 5:19. That means that if a men’s 8+ can race 2000 m in a time of 5 minutes 19 seconds they should be able to achieve a gold medal performance at the either the World Championships or the Olympic Games.

Similarly, the GMS time for a Lightweight Women’s 2X is 6:45. A lightweight women’s 2X should be able to achieve a gold medal performance internationally if they can race 2000 m in a time of 6 minutes 45 seconds. There are GMS times for every boat class that is raced in international competition. GMS times are often inferred for crews for which there is no international event (e.g. Heavyweight Women’s 4+). Junior GMS times are typically used for Masters.

Gold Medal Standard Percentages
What is most useful in the analysis of performance is not the time a crew rows the 2000 m distance but rather the percentage of Gold Medal Standard time (GMS%) achieved. For example, if a men’s 8+ rows 2000 m in 5:53 we want to know what percentage this time represents of the fastest possible GMS time of 5:19.

A time of 5:53 represents a boat velocity of 5.666 m/s as calculated by:

velocity = distance / time = 2000 m / 353 s = 5.666 m/s

Similarly, the GMS time of 5:19 represents a velocity of 6.269 m/s (the velocity associated with the GMS time is called the prognostic speed). So the GMS% achieved by the crew that rowed 2000 m in 5:53 is given by:

5.666m/s / 6.296m/s = 0.9037 = 90.37%

Why are Gold Medal Standard Percentages Useful?
Class Comparison
In the previous example a men’s 8+ rowed a 2000 distance in 5:53. Imagine now that a lightweight women’s 2X covers the same distance in a time of 6:53. Which is the higher quality crew?

The GMS% achieved by the men’s 8+ is 90.37% (as shown in the example above. The GMS time for the lightweight women’s 2X is 6:45. Following the same calculation above the lightweight women’s 2X GMS% is 98.07%. Despite the fact that the men’s 8+ was a full minute faster, the lightweight women’s 2X is the superior crew. While these crews will never race in competition the lightweight women’s 2X will compete in their event at a much higher level. Class comparison is also useful on an ongoing basis. In a weekly time trial crews can measure how they are performing on a regular basis relative to other crews regardless of class. This can be particularly encouraging for developing crews who improve their GMS% each week compared to experienced crews.

Team Selection
Every regatta represents a slightly different level of competition. Achieving a gold medal performance at World Championships is definitely more difficult than winning a gold medal at a local club regatta. GMS can be used to assess the competitiveness of a crew at any competitive stage of rowing.

Example #1: Cut Off Lines
There are 6 crews of both junior men and women that are interested competing at the Eastern Interprovincial Rowing Championships. The coach selects a distance that is reflective of the race distance at that regatta and evaluates the crews in a time trial format.

The results look like:
Crew 1 88.1%
Crew 3 87.9%
Crew 5 87.8%
Crew 2 86.9&
Crew 4 82.1%
Crew 6 79.9%

Which crews should qualify to go to the regatta? This is not an easy question to answer. First and foremost, the selection committee (or coach) must be aware of the philosophy of the team under selection.

Inclusive Philosophy: The inclusive team philosophy is one in which the selection committee (or coach) intends to send a full team to the regatta regardless of the level of competitiveness of each crew. This can be achieved by starting with Crew 1 and working down the ranking until a full team is achieved. This ensures the best and largest possible team but does not consider the team’s competitiveness.

Competitive Philosophy: If the philosophy of the team is to send only those crews that will be competitive it must first be established what GMS% is reflective of a gold medal performance at that specific regatta. Crews that are then close to this level of performance in the time trial should be considered and those that are not should be cut.

To determine the GMS% that is reflective of a gold medal performance for varying regattas coaches and selection committee members must use their expertise and discretion. Often coaches and the selection committee will base the interpretation of the results on one or two crews that are in the time trial that have previously achieved a high level of success at the regatta. For example, if Crew 3 above were a lightweight men’s 2X that were gold medalist at the same regatta a year ago, it can be inferred that a GMS% of ~88% is reflective of a gold medal performance at that level of competition. If Crew 3 cannot be used as relative performance indicator (perhaps Crew 3 has significantly improved or detrained over the year) coaches and selections committees must use subjective experience to establish what % is reflective if a gold medal performance.

Let’s continue to assume that 88% is reflective of a gold medal performance. If the philosophy of the team is to send only gold medal hopeful crews, Crews 1, 3, and 5 should strongly be considered. If the philosophy of the team is to send crews that will simply be competitive, perhaps top qualifying top 3 or making a final of 6 boats, Crews 1, 3, 5, and 2 should be considered.

You will never remove all subjectivity from team selection procedures. GMS are an excellent way to promote fairness, transparency, and to minimize subjectivity.

Example #2 Improving Your Chances
Often at regattas coaches are faced with the dilemma of two events being very close together and having the same athlete(s) in both races. At some regattas “hot seating” is possible but at higher levels of competition you must choose to focus on only one event. GMS% can be used to determine in which event you are most likely to achieve a higher level of performance.

As an example, a coach has to decide whether to race two masters women in a 2X or to include them in a masters women’s 4X. The scheduling of events at a regatta prevents them from racing both events. If the goal is to achieve the highest level of performance the coach could organize a time trial in practice and obtain a GMS% for both combinations of crews over the race distance to determine which crew is performing at the higher level of competition. If the 2X achieves a GMS% of 83.12% and the 4X achieves a GMS% of 84.91%, the coach should race the 4X at the regatta.

Interestingly the coach could also use GMS% to make the exact opposite decision. How? GMS% can be used to assess the competitiveness of a particular event at the regatta. If for example the masters women’s 4X event that the women are going to enter is extremely competitive with the top six boats finishing within 0.5% of each other year after year the coach might opt instead to enter the masters women’s 2X event for which the crew is, according to GMS%, less competitive. If the master’s women’s 2X event normally only has 3 entries with poor GMS% achieved historically, this might be a great shot at a medal.

Common Pitfalls of Using GMS
GMS% Dependence on Conditions
Gathering on water performance data, such as hosting a weekly time trial or timed pieces in practice, allows you to monitor your progress. However, unlike many sports where performance times are highly reproducible, rowing times are not. Times in rowing are significantly influenced by many factors such as wind, current, water temperature, water
depth, and water composition. These factors change from course to course, day to day, and minute to minute. Since times are highly variable so too are GMS%.

As an example, I have personally measured a change in 500 m splits on Lake Banook of 3-5 seconds from April to November as the water temperature increases. You may improve your 1000 m time by as much as 10 seconds over the season and not really be any faster. The improvements are a result of warmer water and less resistance on your hull.

As another example, coaches cannot compare crews GMS% outside of about a 3-4 minute window. If a crew races a 1000 m time trial and another crew follows immediately afterwards GMS% are comparable. However, if both crews are separated by a substantial amount of time wind conditions can significantly change making a relative comparison useless. You can certainly not compare results from crews given time data collected on different days. Unfortunately, coaches do this all the time.

Misinterpreting the Meaning Behind 1%
It is easy to confuse the significance behind the on water time differential between crews when you consider only the GMS%.

If a heavyweight men’s 1X achieves a GMS% of 94.10% and another heavyweight men’s 1X achieves a GMS% of 91.10% it might be tempting to conclude that they are relatively the same speed. After all, there is only a 3% difference in speed between scullers. But what time differential does that 3% represent. In this case, for a GMS of 6:33 for the men’s 1X, a difference of 3% is equal to a 10 second lead! That is approximately 50 m or 6 boat lengths of open water! 1% GMS is a significant amount of time.

How are Gold Medal Standards used in Nova Scotia?
GMS are used in Nova Scotia by the Nova Scotia Rowing Association (NSRA) as part of the provincial team selection document. Crews that aim to compete for the Nova Scotia Provincial Team at the Canada Summer Games, Eastern Interprovincial Rowing Championships, or the National Rowing Championships will be subject to a time trial and assessed using GMS%. As described above, a selection committee (consisting of a mediator and a representative of each club) will draw a cut off line from GMS% results that result from a time trial conducted by the Provincial Team Coach. The Provincial Team coach is normally responsible to select and nominate crews to the time trial stage but is omitted from the final selection process to promote accountability and to remove coach subjectivity. Athletes are made aware of results in a timely manner and a formal appeals procedure is in place.

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