The Acute, Short-, and Long-Term Effects of Endurance Exercise on Skeletal Muscle Transcriptome Profiles.

Area of Science:

• Molecular Biology
• Exercise Physiology
• Genomics

Background:

• Understanding skeletal muscle adaptation to exercise is crucial for disease prevention and therapy.
• Exercise training offers significant health benefits, necessitating a deeper understanding of its molecular underpinnings.
• Cellular and molecular mechanisms of muscle adaptation to exercise require further elucidation.

Purpose of the Study:

• To identify the transcriptional signatures differentiating endurance-trained (ET) and untrained (SED) muscles in young adult males.
• To characterize baseline transcriptional differences and acute exercise-induced transcriptome responses.
• To assess skeletal muscle adaptation by tracking gene expression changes during an 8-week training program.

Main Methods:

• Microarray technology was used to analyze vastus lateralis muscle biopsy specimens.
• Compared baseline transcriptome profiles of ET athletes and sedentary individuals (SED).
• Monitored gene expression changes in sedentary individuals (SED-T) undergoing an 8-week endurance training program.

Main Results:

• Identified distinct baseline transcriptional signatures reflecting differences in oxidative and metabolic capacity between ET and SED muscles.
• Observed upregulation of oxidative adaptation regulators after 3 weeks and a shift towards the ET signature after 8 weeks of training in SED-T.
• Acute intense cycling exercise induced transcriptional responses primarily related to contractile, oxidative, and inflammatory stress, with limited overlap with baseline signatures.

Conclusions:

• Endurance training induces significant, adaptive changes in skeletal muscle gene expression, shifting untrained muscle towards a trained phenotype.
• Acute exercise responses involve complex signaling cascades to manage homeostatic challenges, with quantitative differences in gene induction/repression kinetics between trained and untrained individuals.
• This study provides a comprehensive examination of the transcriptional framework underlying skeletal muscle plasticity in response to endurance exercise.