Renato Canova wrote:
The decrease of speed among the various distances can't be considered a mathematic factor only.
While we can have clear bioenergetics and metabolic connection among the distances using, in different percentage, the same type of physiological mechanism (all the events athletes run at a speed faster than the LT), about marathon the main factor depends on another quality.
We know that the tank of glycogen can last, in hypothetical steady state, for about 1 hour, if the athlete runs in even way at the speed of his LT (of course, we speak about athletes well trained). In this case (distances from 5000m till HM), the most important factor, under metabolic point of view, is the POWER of the engine, and the athlete doesn't be worry about the consumption of fuel (glycogen). So, under methodological point of view, the final goal in order to become faster is to increase the power of the engine, maintaining the level of Aerobic Power and increasing the ability to work in the lactic area.
When we speak about marathon, instead, the problem is HOW TO CREATE THE ABILITY TO MIX FATTY ACIDS AND GLYCOGEN, reducing at Marathon Pace the consumption of super (glycogen) and increasing the consumption of diesel (fatty acids). In many cases, athletes who have a clear trend till HM don't have the physiological possibility to use the most important fatty acids in the best way, since their muscle fibers cannot be oriented in that direction, and the coefficient of decrease becomes higher.
For athletes well trained, and with specific attitude, we try to build a coefficient of 95% of the HM speed.
This means, for example :
61' (2'53"46 / km) in Marathon becomes a pace of [2'53"46 + 5% (8"67)] 3'02"13 (2:08:07)
60' (2'50"61 / km) becomes a pace of [ 2'50"61 + 8"53 ] 2'59"14 (2:06:00)
59'30" (2'49"2 / km) becomes a pace of [ 2'49"2 + 8"46 ] 2'57"66 (2:04:56)
59' (2'47"77 / km) becomes a pace of [ 2'47"77 + 8"39 ] 2'56"16 (2:03:54)
58'30" (2'46"35 / km) becomes a pace of [ 2'46"35 + 8"32 ] 2'54"67 (2:02:52)
This decrease in the speed respects metabolic parameters, in a new situation (looking at consumption of fuel instead than at the power of the engine) and can't be connected with the decrease due to biomechanical factors more than bioenergetics reasons.
The new frontier for Marathon is to try to reduce the decrease from 5% to 4.5% : in this case, we can really speak about "breaking 2" in an elegible marathon.
We have an extrem example what can be done in the Japanese runner Yuki Kawauchi. Best half 1.02.08 and best marathon 2.08.14.....and this on just singles! When we look up on his times in a statistical and mathematical way we get 1.02.08 x 2 + 5 min = 2.09.16 ....... He runs 2.08.14 and 2 x 1.02.08 + 3.58 min= 2.08.14 . Moen`s capacity out from this should at the moment be, 2 x 59.47 + 4-5 min = 2.03.34- 2. 04.34 !