Why did the greatest "ancient marathoner" slow down signficantly in his 70s?

Why did the greatest ancient marathoner of all time slow down so much in the decade of his 70s?

At age 73 Ed Whitlock finished a marathon in 2:54:48. Twenty-five years earlier he ran a marathon in 2:31:23. In a quarter of a century his marathon time decreased by only 23 minutes. See here for the blog Cannute's Efficient Running Site 's tribute to Whitlock.

Whitlock's 02 max was measured at 52.8 ml/kilo/min when he was aged 70 and 11 years later at age 82 a measured Ox max was essentially unchanged ( 54 ml/kilo/min).Yet during this general time period his marathon times decreased signficantly.

A person's maximal oxygen consumption ( 02 Max) decreases with age. The per decade decrement is generally said to be between 5 and 10 Percent. The jury is still out regarding if the rate of decline in endurance athletes is more,less or the same as more sedentary humans. There is good evidence indicating that the rate of decline increases around age 70 and values as high as 15 % percent per year or more have been reported. Assuming the 02 Max measurements are correct, Whitlock's 02 max was essentially unchanged during his running trek through his  70s but his marathon times decreased significantly.

As commented on by Cannute, Whitlock in his 40s was a very good marathoner but was not setting world age marathon records . At age 48 he ran a marathon in 2:31:23- a very good time for age-actually any age- but not the record.  Ye,t by age 70 he was setting marathon records for age and continuing setting records until a few months before his death at age 86.He set the age 85plus marathon record in Toronto clocking in a 3:56:33

So what was his secret? Obviously his genetic endowment included a high 02 max. His marathon times did decrease between age 70 and age 80. He was running sub four hour marathon at 80 plus while running sub 3 hour at 70 plus while his measured 02 max seemed constant over that time period.

Of course there is more to running marathon than 02 max.

Whitlock's training in his 70s and 80 did not follow the current generally accepted marathon training  principles. He did no speed work except in races. In his 70s he is said to  have run up to 3 hours a day , almost every day at a very slow pace, described  by him as a "slow shuffle". He carried the LSD (long slow distances) program to a extreme.

Tim Noakes, noted exercise physiologists and long time endurance athlete, believes that a major reason than marathon times decrease markedly in the decade of their 70s is that most older runners cannot maintain the hours of training necessary to perform well in the marathon  in part because  there are too many minor ( and major injuries), too many aches and pains. The muscles endure better than the "connectors", i.e the structures and tissue connecting the bones to the muscles and joints.

Yet it may be that even in the absence of significant injury or a nagging series of minor injuries and even with high level of training  a human's running speed for distance decreases significantly during the 8th decade of life. (about 25% decrease in marathon running speed for the world's greater old timer marathoner.) One suspect to consider is  muscle loss of "spring function" and the spring function of tendons and the arch of the foot. You figuratively and maybe literally loose the "spring in your step".