How to create a level playing field across ages

 

Integrated age/sex/bodyweight correction system for indoor rowing

Vianney Koelman

Dutch Eindhoven Rowing Association Beatrix

Competitive indoor rowing relies on seperating the field into classes for age, bodyweight and gender. This, however, causes considerable fragmentation of indoor rowing competitions. It is not uncommon for these competitions to take the shape of a myriad of seperate events in many of which no more than a few athletes compete.

Can we avoid this fragmentation and still be inclusive towards aging athletes and athletes with smaller bodies? The answer is yes. We can even fully eliminate any fragmentation while allowing for a fair comparison between male and female athletes of widely different ages and encompassing a vast range of body sizes. This can be realized in a fun and easy to implement single mass event.

 The whole system is based on two key ingredients: 1) the incorporation of weight via Kleiber’s scaling of wattage versus body weight; and 2) the incorporation of age via a differential slowness parameter.

Skipping all theory aspects, we jump straight to the resulting correction formula for race times. This takes the shape:

Here t denotes the individual race time, tcorr the corrected time, M the body mass, and  M0 = 74 kg for male athletes, while M0 = 102 kg for female athletes. The age-dependency of the corrected time is incorporated in the differential slowness S, a number given by

where y denotes the age of the athlete (in years), y0 = 20, and y1 =   105.  

To check how well this integrated correction algorithm succeeds in creating a level playing field, we first consider the age correction aspect. This is done by applying the algorithm to the world record 2k times for lightweight men of age 30 to 90 years. By focusing on the world’s fastest lightweight rowers, we fix the variable M (body weight) to a value at (or narrowly below) 75 kg. As a comparison we also include the results following from two age-handicap systems derived for on-the-water rowing. These are the USRA age handicap algorithm ( https://hosr.org/handicaps/ ), and the DeMaas age correction algorithm (https://de-maas.nl/correctiefactoren/bestanden/handicapfactoren.html ). Both these methods are frequently used in indoor rowing as well. The results for the three methods are visualized in below graph.

 

The pronounced deterioration of the raw finish times with age is clearly visible. In creating a level playing field for indoor rowing, the current integrated algorithm is much more successful than the USRA and DeMaas algorithms.For indoor rowing apparently the two latter algorithms both overcorrect at older ages. This should not surprise, as on-the-water rowing and indoor rowing are distinct sports that are likely to come with their own ageing characteristics. For instance, muscle atrophy that contributes strongly to deterioration of performnce with age, has likely a more pronounced effect on on-the-water rowing than on indoor rowing. This is because a relative increase in 'dead' body weight contributes to slowing down on the water via a relative increase in water displacement and hence a relative increase in drag, an effect entirely absent in indoor rowing.  

For other distances, similar results are obtained. Below graph shows the three correction methods at work for 5k lightweight men indoor rowing world record performances. Again, the USRA and DeMaas algorithms tend to over-correct at older ages.

Testing the integrated algorithm is done by applying it to a dozen 2k indoor rowing world record performances for male and female athletes of widely different ages and body weights. Below table summarizes the results.

 

 While the raw times cover a variability of well over four minutes, the correction algorithm reduces this variability by more than 93% to a mere 18 seconds.