אימוני כח- מסה

[גולן]

נושא הבא, כידוע לכם בעבר שוחחנו על המונח היפרפלזיה, התרבות סיבי שריר חדשים ותאי שריר!

אני רוצה להציג בפניכם מחקר מעניין שבדק זאת על שחקני פוטבול, וכן, מדובר בשימוש בסטרואידים אנאבוליים.

Athletes who use anabolic steroids get larger and stronger muscles. How this is reflected at the level of the muscle fibers has not yet been established and was the topic of this investigation. METHODS: Muscle biopsies were obtained from the trapezius muscles of high-level power lifters who have reported the use of anabolic steroids in high doses for several years and from high-level power lifters who have never used these drugs. Enzyme-immunohistochemical investigation was performed to assess muscle fiber types, fiber area, myonuclear number, frequency of satellite cells, and fibers expressing developmental protein isoforms.

RESULTS: The overall muscle fiber composition was the same in both groups. The mean area for each fiber type in the reported steroid users was larger than that in the nonsteroid users (P < 0.05). The number of myonuclei and the proportion of central nuclei were also significantly higher in the reported steroid users (P < 0.05). Likewise, the frequency of fibers expressing developmental protein isoforms was significantly higher in the reported steroid users group (P < 0.05). [these researchers found embryonic fiber development in the nonsteroid using group as well...just not as much as in the group using.]


CONCLUSION: Intake of anabolic steroids and strength-training induce an increase in muscle size by both hypertrophy and the formation of new muscle fibers (hyperplasia). We propose that activation of satellite cells is a key process and is enhanced by the steroid use. The incorporation of the satellite cells into preexisting fibers to maintain a constant nuclear to cytoplasmic ratio seems to be a fundamental mechanism for muscle fiber growth. Although all the subjects in this study have the same level of performance, the possibility of genetic differences between the two groups cannot be completely excluded."


: Kelley G. Mechanical overload and skeletal muscle fiber hyperplasia: a meta-analysis. J Appl Physiol. 1996 Oct;81(4):1584-8.

2: Antonio J, Gonyea WJ. Muscle fiber splitting in stretch-enlarged avian muscle. Med Sci Sports Exerc. 1994 Aug;26(8):973-7.

3: Antonio J, Gonyea WJ. Progressive stretch overload of skeletal muscle results in hypertrophy before hyperplasia. J Appl Physiol. 1993 Sep;75(3):1263-71.

4: Antonio J, Gonyea WJ. Role of muscle fiber hypertrophy and hyperplasia in intermittently stretched avian muscle.


J Appl Physiol. 1993 Apr;74(4):1893-8.
"Title: Effects of anabolic steroids on the muscle cells of strength-trained athletes.

Researchers: Kadi F, Eriksson A, Holmner S, Thornell LE Department of Integrative Medical Biology, Umea University, Sweden.