Véronique Billat,1 Laurence Hamard,1 Jean Pierre Koralsztein,2 and R. Hugh Morton3
1Faculty of Sport Sciences, University of Evry-Val d'Essonne, Evry, France; 2Sport Medicine Center CCAS, Paris, France; and 3Institute of Food, Nutrition, and Human Health, Massey University, Palmerston North, New Zealand
Submitted 28 September 2008 ; accepted in final form 26 May 2009
http://www.billat.net/attachments/120_differential%20modelling.pdf
(…) The present study examines the hypothesis that running speed is regulated by the prevailing anaerobic store at each instant of the race. If this hypothesis can be supported, despite the progressive depletion of the anaerobic stores, then PAN at each instant of the race would allow a time to exhaustion at PAN (tlim PAN) to be maintained constant until the last several meters of the race, whereupon it becomes an all-out rather than a controlled exercise. (…)
(…) Furthermore, it has recently been reported that 800-m runners demonstrated an oxygen uptake (VO2) drop below V˙O2max, which additionally taxes the anaerobic stores (55). This V˙O2 drop could be due to the metabolic acidosis, which impairs mitochondrial respiration (30). Therefore, middle-distance speed must be as high as possible above the maximal aerobic power (i.e., the product of V˙O2max by the
oxygen cost of running) to achieve a good final performance but without depleting anaerobic stores too early and without decreasing VO2 below VO2max by an inhibition of oxidative phosphorylation with early acidosis (11, 37, 53). Furthermore, the recent work of Jones et al. (32) on pacing strategy showed that a fast start would contribute to improved exercise tolerance because of a more rapid increase in oxygen uptake. (…)
(…) This result suggests that the time spent running at the chosen instantaneous anaerobic power during this portion of middle-distance races may be a consequence of an anaerobic energetic controller of speed.
This may well be related to the perception of exhaustion as previously reported for blood lactate accumulation (9). Furthermore, 1,500-m performance is related to tlim PAN, which depends on a careful first half racing speed selection, while performance over 800 m is related to the total anaerobic stores. Furthermore, tlim PAN decreased almost significantly (P _0.06) after the initial phase ofVO2max steady-state achievement in the 800-m but not the 1,500-m race. (…)