Marathon

Participants in the 2010 Boston Marathon in We...

Participants in the 2010 Boston Marathon in Wellesley, just after the halfway mark (Photo credit: Wikipedia)

http://www.CharlesEugster.net

Although the Boston Marathon was marred by tragedy the Boston and London Marathons were glorious symbols of human endurance, determination, and perseverance.

Participation at a Marathon requires training of about 4 months prior to the event. With a peak of less than 56km per week training there seems to be a risk of some heart damage or dysfunction. Intensive training is really necessary.

Although deaths have been recorded, the number is relatively small at 1:50,000 (J. Am. Coll. Cardiol. 28(2):428 1996) and is comparable to athletics at 1:43,000 (Nat. Coll. Athletic Ass.). Women have a far lower risk of death at 1:200,000 at Marathons. (B.M.J. 47:68 2013).

However those participants with a sickle cell trait are at risk, as they have a 37 times higher death rate (Br. J. Sports Med. 46:325 2012). The average age of death was 41.   ( B.M.J. 335:1275 2007).  The oldest recorded death was at about 57.

Thus it seems that, in spite of the fact that many runners were found to be positive for the Troponin test after the race which usually indicates myocardial infarction, the old and very old Marathon participants seem to be statistically almost risk free!

While the record is just over 2hrs, most participants aim for about 4hrs.  The oldest record holders are Mr Singh at 100 at 8hrs 11mins and Ms Burrill at 92 with 9hrs 53mins. To keep going for 8-10 hours in extreme old age is truly amazing. The old that complete a marathon have exceptional endurance and extraordinary determination.

Should we, in old age, emulate and follow their example as has been suggested by some physicians?

I personally think not, in spite of the fact that risks seem to be minimal. The first runner’s source of energy is glycogen (carbohydrate). Lipids (fat) become the primary source of fuel once the glycogen stores are depleted. This is followed by glucogenisis whereby calories are made available from protein by extracting amino-acids from muscle tissue (Med. Sci. in Sports & Exercise 19:179 1987). Thus during the last phase of the Marathon, muscle protein breaks down (Adv. Nutr. & Human Met. 5th ed. 2009). In other words not only fat but muscle tissue is broken down during a Marathon.

It should be no surprise that the Marathon elite look “like matchstick men”, lacking fat and muscle mass.  Muscle glycogen depletion also causes (temporary) stress on the immune system. Given sufficient time the loss of muscle mass in the young can be compensated by hypertrophy exercises. But due to reduced protein synthesis this is extremely difficult in old age. Sarcopenia or the loss of muscle mass is the major cause of disability in old age.

As participation in a Marathon causes the loss of muscle mass and weakening of the immune system at the same time, it does not sound like something that can be universally recommended for the aged runner.

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