3. We often hear the phrase ‘no pain no gain.’ Is that really true however? Scie

Question

3. We often hear the phrase ‘no pain no gain.’ Is that really true however? Scientists
set out to test this in the following article: http://jeb.biologists.org/content/214/4/674 (PDF also available on Moodle). Read the Summary, Introduction, and Discussion sections of this article as well as skim the remaining sections to understand the article.

a. What do the scientists mean by Naive and Pre-Trained?

b. How did the scientists know there was muscle damage in the Naive group?

c. Why was eccentric exercise chosen?

d. What measurements did the scientists use to compare the end result of the exercise between the groups?

e. What were their overall conclusions?

Explanation / Answer

a) Naive and pre-trained were two experimental groups. The pre-trained group received an additional initial three week gradual ramp-up exercise routine. Whereas naive group were directly introduced in the experiment in the fourth week and were subjected to the eccentric exercise with out any gradual amp-up exercise routine. Both groups were at the same exercise intensity at this period. The purpose of these two groups were to not develop damage i.e. in the pre-trained group through gradual and progressive introduction of high eccentric forces and to develop muscular damage i.e. the naive group through high eccentric forces.

b) The scientists checked for the  levels of plasma CK, self reporting muscle soreness to determine the extent of muscle damage in both groups. Both groups were subjected to the same intensity of exercise fourth week onwards. Results showed that the mean CK levels in case of the PT group remained below 107Ul–1[150 Ul–1 (=normal)],indicating no demonstrable muscle damage throughout the training period.However the Naive group had the mean CK levels above normal, peaking on week 5 at 580±160 U l. The CK levels of the naive group was significantly higher than that of the Pre-trained group, thus indicating the presence of muscle damage in the Naive group. The initial perceived soreness (4 weeks) was also significantly higher in the naive group. Both these factors confirmed that the Naive group had muscle damage.

c) An eccentric exercise regime was chosen because highest force production in skeletal muscles is observed in this exercise and due to these high forces, muscle damage is commonly observed. Moreover this muscle damage can be avoided through gradual and progressive increase in the intensity of the exercise. Hence the exercise regime is apt to study difference in muscle damage and subsequent muscle remodeling or growth.

d) Measurements for muscle size and strength such as quadriceps muscle size (i.e. volume) using MRI, Maximum voluntary isometric strength were used to compare the end result of the exercise between the groups. Additionally levels of the mRNA encoding the mechano growth factor IGF-1Ea was also used.

e) Since there was no significant difference in the muscle size and strength as well as mechano growth factor IGF-1Ea in both the PT and NA groups, it can be concluded that muscle damage is not required for muscle rebuilding.

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