It is fairly well known that the longer you train the harder it is to come by noticeable gains. It is also true that if you have an excessively high volume, your progress can come to a grinding halt and even end up in reverse! But why is that? Believe it or not, it goes all the way down to your DNA! Researchers have discovered that how well you recover over time (such as a 20 year old vs. a 40 year old) is dependant on small sections of your DNA that govern muscle cell repair and growth. Here's how it went down.
They took 2 groups of endurance based athletes, both men and women, that were selectively recruited over the course of three years. One group was made of 13 subjects who fit the criteria for 'Fatigued Athlete Myopathic Syndrone (FAMS). Also known as chronic fatigue, in these cases it is a result of their training volume. Essentially they are doing the same amount of work they have in the past, but are now un able to keep up in terms of recovery. Excessive soreness, fatigue, muscle stiffness, etc.
And their was a control group who did not display these symptoms. The groups were matched for age, and training volume. That means for every person in the FAMS group there is some one who is the same age, and has the same training volume but is apparently healthy. Subjects included tri-athletes, cyclists, and distance runners
|Age (yr)||42 +/- 10||41.2 +/- 11|
|Height (cm)||174 +/- 8.2||173 +/- 9|
|Weight (kg)||74 +/- 18||70 +/-10|
|VO2max (ml/kg/min)||70 +/-10||52 +/-10|
|Training Vol (km/wk)||52 +/- 12||67 +/- 24.3|
They tested for a number of things including, maximal voluntary contraction on the leg extension, and VO2max using a graded treadmill test. The main focus was the length of small proteins on the end of chromosomes called Telomeric restriction fragments (TRF). These telomeres are what signal general cells, called satellite cells. Satellite cells are cells that have not been specialized into a specific tissue and upon request can be differentiated into new cells to repair damaged or create new tissues. In the case of muscle damage, they are differentiated into muscle cells.
Research has shown that with each cell division of these satellite cells, the TRF shorten. They wear down in a sense. Once they reach a critical length, your body recognizes that strand of DNA to be damaged and it will stop functioning. Your ability to repair and grow new muscle tissue is diminished. A little bit here, a few strands of DNA there - It adds up over the years. To determine length they took muscle biopsies from the quadriceps muscles and ran it all through a number of special gadgets.
The researchers found that the subjects with FAMS had significantly shorter telomeres than those in the control group. Even when they were corrected for age, the FAMS group had significantly shorter telomere lengths. By corrected for age, which means they estimated how long they should be based on their ages because it has been shown that these telomeres diminish in size at a rather constant rate until roughly 85 years of age(2).
This study helps to explain why gains in size and strength are harder to come by the longer we train. The also help to explain why some people can tolerate more than other and why some people grow faster than other. If your telomeres diminish at a much slower rate, then gains is size will stay rather constant over the years. You will also be able to recuperate much faster than others. Just how much of a factor does this play in how much a person can tolerate and recover from?
Well the subjects in this study had to decrease their frequency from 5 to 3 days a week, their 5K time decreased by 30% and their training volume dropped from 68 to 23 km per week. This reduction in training volume and intensity was to allow for sufficient recovery. And this drop in training lead to their decrements in performance.
These may be extreme cases of FAMS, but it shows not only that genetics play a roll in progress and performance, but it also points to how. This does not mean that some of us will never have a great body or do not have the potential to be bodybuilder, or strength/power athletes. It just means that training programs should be tailored to an individuals recuperation ability. There is no immediate benefit to over training.
- Collins, M., V, Renault, L., A, Grobler, A. St Clair Gibson, M. I. Lambert, E. W. Derman, G. S. Butler-Browne, T. D. Noakes, and V. Mouly (2003). Athletes with exercise-associated Fatigue have abnormally short muscle DNA telomeres. Med. Sci. Sports Exerc., 35, 9. 154-1528.
- Decarv. S/. V. Mouly, C. Ben Hamida, A Sutrt, J. P. Barbet, and C. S. Butler-Brown. (1997). Reflective potential and telomere length in human skeltetal muscle: implications for satellite cell mediated gene therapy, Hum Gene Ther, 8, 142901438