Mark Lyttle

Quantitative Analysis of Sailing Races using GPS data

Abstract

Quantitative analysis of sailing races in one-design boats using GPS devices can provide an insight to the main factors likely to impact the rank order. These factors include the sailors’ skill in steering the boat and trimming the sails but also the route chosen and whether they are already ahead after the start or the 1^st leg. GPS position, location, speed and distance data of each boat in 13 elite races, with fleet sizes between 9 and 60, was examined using Spearman and Pearson correlations. It was found that the final rank order correlates significantly (P < 0.01) with 1^st mark rank order in 84.6% of races in the sample (n = 13) and the 1^st mark rank order correlates significantly with the rank orders 50% through the 1^st leg and 1 minute after the start in most races (53.8% and 66.7% respectively). Results also show that in each race different factors affect the speed and distance travelled of each boat, meaning there is no consistency between races or within races over whether speed or distance is dominant. Finally a method is examined, and partially validated, to extract common themes in a fleet for routes chosen on the 1^st leg.

Jury is out on cold water immersion prior to or during exercise

There has been a growing trend to cold water immersion prior to exercise. Studies on the effect of cold water immersion or cryotherapy, prior to or during exercise, on EMG activity of muscles have been divergent, with some studies showing negative effects. One study, reported concerns about the return to exercise after cooling and advised careful use of cryotherapy before activities that demand good sensory-motor control in order to protect the physical integrity of the athlete.

A study¹ in the latest Journal of Sports Sciences found that cold water immersion prior to vertical jumping decreased EMG response and flight time for up to 30 minutes.

Cryotherapy in sports appears to be often used indiscriminately and uncontrollably and this study indicates the need for caution in performing physical activities immediately after cryotherapy due to short-term changes in muscle response. “Therefore, cold water immersion should not be used prior to rehabilitation or sports activities that demand great muscular or balance activity.”

Cold-water immersion alters muscle recruitment and balance of basketball players during vertical jump landing

Playing the numbers

I ran read about Sunderland’s recent record before tonight’s game with Arsenal and was bemused – 11 points from 7 games. Extrapolated to 38 games in a season in the Premier League, Sunderland would be challenging for Europe and it is well ahead of the accepted thought that an average of one point per game over the season avoids relegation. Something to be positive about, except that 11 points from 7 games is barely more than one result better than that average – and given the unpredictable nature of football and sports in general, their recent form may just be the turn of the dice