Ewen, as you imply, De Castella’s demanding 10 mile sessions including fairly fast down-hill running at Stromlo almost certainly contributed to his good performance in Boston, but it is intriguing to speculate that they might also have contributed to the fact that he is now ‘well and truly retired’ at 51. Of course there are many possible reasons why a former world record holder might choose to take it easy as middle age approaches.
However, it is disconcerting that some evidence indicates that elite athletes who stop training tend to deteriorate faster in middle age than sedentary individuals. In a comparison of 64 sedentary men with 89 endurance-trained men, Pimentel and colleagues (Journal of Applied Physiology, volume 94, pp 2406-2413) found a more rapid decline in maximum oxygen uptake (VO2max) after age 50 in the endurance trained men. Not surprisingly the accelerated deterioration was associated with reduced training volume, though the causal mechanism was not established. In a 30 year follow-up study of men who had participated in the 1966 Dallas bed rest study in their youth, McGuire and colleagues (Circulation, 104, 1350-1357, 2001) found that the cardiovascular deterioration due to 3 decades of aging was less than that due to 3 weeks of bed-rest at age 20. Of special note with regard to the mechanism of deterioration, they found that the decrease in VO2max could be attributed mainly to decreased ability of muscle to extract oxygen from blood. In other words, the deterioration with age was largely due to deterioration within the muscles, though whether this deterioration was merely a loss of aerobic enzymes, or to the loss of fibres, and/or capillaries is unknown.
In the 4th edition of his book ‘Lore of Running’, Tim Noakes proposes that the springiness of muscles is significantly compromised by large numbers of runs over 21k, and he advocates that runners seeking a sustained quality running career should minimise eccentric muscular damage. So, I will continue to be cautious about forms of training that focus on eccentric contraction. Maybe the most important thing is allowing adequate recovery, especially when the legs start to show signs of cumulative fatigue over several consecutive days.
With regard to the recovery from my recent hamstring injury, my easy 7 Km run today went well despite the rather stripey weather. Fitful sunshine alternated with brief flurries of snow. Although the flurries were brief, the flakes were small and compact, typical of polar snow borne by a north-easterly airstream. Nonetheless it was good to be out of doors. After a gentle warm up, I gradually increased pace up to 5:30 min per Km for the 6th Km and was not aware of any discomfort in my hamstring. So I hope that after a week or two of gentle running I will be able to return to moderately intense efforts by mid February.