Archive for physiology

fast and curious

Posted in Running, Statistics with tags , , , , , , , , , on April 28, 2024 by xi'an

A paper in Frontiers attempted modelling the optimization of world-class 400 m and 1,500 m running performances using high-resolution data.

“In the present study, rather than using statistical analyses of 100-m split times or big data, we choose to analyze a select sample of World-class athletes individually using high-resolution data and fit a mathematical model to their pacing profiles. This mathematical model allows us to perform further predictive simulations and analyze the effect  of different physiological variables on performance. “

The model used in this analysis is a deterministic system of equations depending on half-a-dozen parameters like (of course!) the VO² max. Most of them “are not measured for any individual athlete (e.g., using experimental methods), but are estimated through a computation to fit the data for a specific race and athlete.”

The authors then turn cranks to see how each parameter increases the speed curve, as in the graph below for Femke Bol winning the 2022 European Championship 400m in München and the impact of increasing final VO², anaerobic energy e⁰, or propulsive force. And the same for Jakob Ingebrigtsen’s 1,500m win [above graph]—in a time shorter than my current 1,000m best! What is unclear to me is how the model repercusses the toll of such increases on the athlete’s other parameters—since Ingebrigtsen already has an amazing VO² max!. Some of the changes leads to a 5sec improvement, which is quite large at record levels—the World record for men moved by 1s between 1998 and 2022. I’d thus be interested in a field experiment where one of these top runners would attempt to implement the suggested changes in their pace to see how much this impacts the other factors… Another experiment with the fitted model is to check the impact of the lane allocated to the runner for a 400m race, the fastest lane being the first one despite higher centrifugal forces on the bends. Which seem to have a lesser if still noticeable effect on the 1,500m race [above graph].

 

Bayes on the radio

Posted in Books, pictures, Statistics, University life with tags , , , , , , , , , , , , on November 10, 2012 by xi'an

In relation with the special issue of Science & Vie on Bayes’ formula, the French national radio (France Culture) organised a round table with Pierre Bessière, senior researcher in physiology at Collège de France, Dirk Zerwas, senior researcher in particle physics in Orsay, and Hervé Poirier, editor of Science & Vie. And myself (as I was quoted in the original paper). While I am not particularly fluent in oral debates, I was interested by participating in this radio experiment, if only to bring some moderation to the hyperbolic tone found in the special issue. (As the theme was “Is there a universal mathematical formula? “, I was for a while confused about the debate, thinking that maybe the previous blogs on Stewart’s 17 Equations and Mackenzie’s Universe in Zero Words had prompted this invitation…)

As it happened [podcast link], the debate was quite moderate and reasonable, we discussed about the genesis, the dark ages, and the resurgimento of Bayesian statistics within statistics, the lack of Bayesian perspectives in the Higgs boson analysis (bemoaned by Tony O’Hagan and Dennis Lindley), and the Bayesian nature of learning in psychology. Although I managed to mention Poincaré’s Bayesian defence of Dreyfus (thanks to the Theory that would not die!), Nate Silver‘s Bayesian combination of survey results, and the role of the MRC in the MCMC revolution, I found that the information content of a one-hour show was in the end quite limited, as I would have liked to mention as well the role of Bayesian techniques in population genetic advances, like the Asian beetle invasion mentioned two weeks ago… Overall, an interesting experience, maybe not with a huge impact on the population of listeners, and a confirmation I’d better stick to the written world!