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Early accentuated muscle hypertrophy is strongly associated with myonuclear accretion.
- Source :
-
American journal of physiology. Regulatory, integrative and comparative physiology [Am J Physiol Regul Integr Comp Physiol] 2020 Jul 01; Vol. 319 (1), pp. R50-R58. Date of Electronic Publication: 2020 May 20. - Publication Year :
- 2020
-
Abstract
- The current study explored whether the marked hypertrophic response noted with a short-term unilateral concurrent exercise paradigm was associated with more prominent changes in myonuclei accretion, ribosome biogenesis, and capillarization compared with resistance exercise alone (RE). Ten men (age 25 ± 4 yr) performed aerobic and resistance exercise (AE + RE) for one leg while the other leg did RE. Muscle biopsies were obtained before and after 5 wk of training and subjected to fiber-type specific immunohistochemical analysis, and quantification of total RNA content and mRNA/rRNA transcript abundance. Type II fiber cross-sectional area (CSA) increased with both AE + RE (22%) and RE (16%), while type I fiber CSA increased mainly with AE + RE (16%). The change score tended to differ between legs for type I CSA ( P = 0.099), and the increase in smallest fiber diameter was greater in AE + RE than RE ( P = 0.029). The number of nuclei per fiber increased after AE + RE in both fiber types, and this increase was greater ( P = 0.027) than after RE. A strong correlation was observed between changes in number of nuclei per fiber and fiber CSA in both fiber types, for both AE + RE and RE ( r > 0.8, P < 0.004). RNA content increased after AE + RE (24%, P = 0.019), but the change-scores did not differ across legs. The capillary variables generally increased in both fiber types, with no difference across legs. In conclusion, the accentuated hypertrophic response to AE + RE was associated with more pronounced myonuclear accretion, which was strongly correlated with the degree of fiber hypertrophy. This suggests that myonuclear accretion could play a role in facilitating muscle hypertrophy also during very short training periods.
- Subjects :
- Adult
Capillaries physiology
Humans
Hypertrophy
Leg anatomy & histology
Leg physiology
Magnetic Resonance Imaging
Male
Muscle Fibers, Fast-Twitch physiology
Muscle Fibers, Fast-Twitch ultrastructure
Muscle Fibers, Slow-Twitch physiology
Muscle Fibers, Slow-Twitch ultrastructure
Muscle, Skeletal growth & development
Muscle, Skeletal ultrastructure
Physical Endurance
RNA biosynthesis
Resistance Training
Ribosomes metabolism
Young Adult
Cell Nucleus metabolism
Exercise physiology
Muscle, Skeletal physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1522-1490
- Volume :
- 319
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- American journal of physiology. Regulatory, integrative and comparative physiology
- Publication Type :
- Academic Journal
- Accession number :
- 32432913
- Full Text :
- https://doi.org/10.1152/ajpregu.00061.2020