Ribosomes are the essential machinery for cellular protein synthesis. Ribosome content is hypothesized to support muscle growth and is suggested that those with more ribosomes may better respond to resistance training. Aerobic training also elicits distinct physiological adaptations; however, no direct measures of ribosome content following aerobic training have been measured. Ribosomes interact with mitochondria for mitochondrial protein synthesis and import. Mitochondria may also provide cellular energy to ribosomes. We hypothesized that aerobic and resistance training would increase ribosome content and that ribosome content following aerobic training would correspond to changes in mitochondrial-related protein content and gene expression. Fourteen young men and women performed 6 weeks of single-legged aerobic followed by 10 weeks of bilateral resistance training. Muscle biopsies were taken following aerobic (Pre RT) and resistance training (Post RT) in the aerobically trained (EX) and control (CTL) legs. Pre RT, EX had greater COXIV staining intensity in Type 1 (1.17-fold; p=0.020) and Type 2 (1.22-fold; p=0.015) fibres compared to CTL; however, no differences in whole-muscle mitochondrial-related protein content or gene expression were observed (p>0.05). No differences in regulatory (UBF, Cyclin D1, TIF-1A, POLR-1B), cytosolic (45S, 5.8S, 18S, 28S rRNAs) or mitochondrial (12S rRNA) ribosome-related gene expression were observed (p>0.05), except for c-Myc (CTL>EX; p=0.034) and 5S rRNA (Pre RT CTL<Pre RT EX; p=0.076). When stratified for leg-lean soft tissue mass (LLSTM), legs with greater LLSTM had lower expression in 3/13 ribosome-related genes (p<0.10). When stratified for ΔLLSTM following resistance training, legs with the greatest ΔLLSTM had lower expression in 11/13 ribosome-related genes prior to (p<0.10) and less change or decrease in expression in 9/13 genes following resistance training (p<0.05). These results indicate that baseline ribosome content was sufficient to support aerobic adaptations (capillarization, VO2 peak) that were previously observed and that ribosome’s efficiency, rather than content, is likely more important to support increases in muscle hypertrophy following resistance training. / Thesis / Master of Science in Kinesiology / Ribosomes are essential in making proteins within the cell, and their content has been hypothesized to support the adaptive responses observed with exercise training. Ribosome content has previously been shown to increase following resistance training likely to support skeletal muscle growth. However as aerobic training also influences cellular adaptations, it is plausible that ribosome content also supports these training adaptations. We hypothesized that both aerobic and resistance training would increase ribosome content. Contrary to our hypotheses, no changes in ribosome content were observed following aerobic or resistance training despite previously observing adaptations characteristic of each respective training stimulus. However, those with the greatest increases in muscle mass had lower baseline ribosome content and less change in content following resistance training. These results suggest that baseline ribosome content is sufficient for aerobic adaptations and that ribosome’s efficiency is likely more important than content to elicit resistance training adaptations.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/26886 |
| Date | January 2021 |
| Creators | Brown, Alex |
| Contributors | Parise, Gianni, Kinesiology |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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