Resistance exercise training modulates acute gene expression during human skeletal muscle hypertrophy

Area of Science:

• Exercise Physiology
• Molecular Biology
• Genetics

Background:

• Acute resistance exercise (RE) triggers gene expression changes in muscle.
• It is unclear how prior RE training influences these acute responses.
• Understanding this is crucial for interpreting exercise-induced adaptations.

Purpose of the Study:

• To investigate if RE training modifies acute RE-induced gene expression patterns.
• To compare gene expression in trained versus untrained muscle following an acute bout of exercise.
• To determine if gene expression accurately reflects muscle adaptation to training.

Main Methods:

• Thirteen untrained subjects underwent 12 weeks of unilateral arm RE training.
• An acute RE bout was performed on both trained and untrained arms.
• Gene expression (mRNA levels) and protein signaling (rpS6 phosphorylation) were analyzed 4 hours post-exercise.

Main Results:

• RE training induced muscle hypertrophy and increased strength.
• Trained muscle showed attenuated anabolic signaling (reduced rpS6 phosphorylation) post-exercise.
• RE training modified acute RE-induced gene expression in a divergent and gene-specific manner.
• Changes in gene expression were multidimensional and did not directly correlate with adaptive responses.

Conclusions:

• RE training selectively alters the acute molecular response to exercise.
• Relying solely on acute gene expression may misrepresent long-term exercise adaptations.
• Gene expression is a complex marker and its interpretation requires consideration of training status.