Thursday, June 07, 2012

Muscle soreness after marathon-what do the muscle biopsies show?

I have completed marathons for 35 years and an interesting ( at least to me) change in the pattern of post marathon recovery time has emerged. When I as younger and more foolish I would train faster ( a relative term) and attempt to hit a target time for the race. For several years, I would strive to finish in under 3 1/2 hours. In the 2-4 days after those races, my quadriceps were sore and tender , the soreness peaking on day 2 and was particularly evident on attempting to walk downstairs.

This phenomenon is called delayed onset muscle soreness (DOMS).Although lactic acid buildup was once said to be the cause now the thinking is that the key element is eccentric exercise with damage to the muscle fibers and lactic acid exonerated.Neither post exercise icing nor use of NSAIDs seem to help but there is some fairly unconvincing data suggesting that post run massage might mitigate the soreness a bit.Well it feels good anyway.

In recent years there is no significant post race soreness in the thighs at anything near the level experienced earlier in my running odyssey. I developed the habit (obsession) of typically covering a long training distance on the weekends, running about 20 miles on a typical Saturday with no soreness on Sunday.

What do muscle biopsies demonstrate after marathons?

Here is a full text article from the American Journal of Pathology 1985 by M.J. Warhol. Muscle biopsies were done on the lateral gastrocnemius muscle of forty runners 48 hours after a marathon and again at one week, one month and 8-10 weeks. Light and electron microscopy were done.

At 48 hours there was damage to the myofibrils with abnormal findings evident in the mitochondria and sarcoplasmic reticulum. The damage was patchy and quite variable in extent from one runner to the next, with some demonstrating very little damage. Type II ( fast-twitch) fibers seemed to be more damaged. By day seven, "ghost cells" (empty muscle cells) were seen and satellite cells appeared. By one month there was continuing evidence of muscle cell regeneration but the pathological changes had largely resolved. There was no inflammatory cellular response reported in this paper but another report did describe some inflammatory cells.Some runners showed evidence of fibrosis. By 12 weeks there was continued electron microscopic evidence of muscle cell regeneration.

Similar light microscopy findings were reported earlier by RS Hikida ( with senior author D Costell ) in the Journal of Neuro Science 1983,May 59(2),195-203. However, their results differed in that they reported evidence of inflammation while Warhol suggested those changes were due to the trauma of the biopsy. Hikada also did pre-race biopsies showing some of the same changes prompting the suggestion that the intensive training for the marathon may have caused similar cellular changes.

A pattern emerges of damage to muscle cells that drop out and are replaced by new cells.

If the type II fibers are disproportionately affected perhaps my slower times and less participation by my type II fibers might account for the lack of post race soreness. Type II fibers kick in as the energy output increases moving toward the maximal oxygen uptake and when glycogen stores are depleted.Further the sarcopenia of aging also disproportionately targets type II cells so I may have less muscle cells at risk and I run so slowly that my fast twitch fibers for the most part have the day off.

What data are available regarding morphological changes in the muscles of athletes who exercise at high levels for many years? So far I have been unable to find any.

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