Similar expression of oxidative genes after interval and continuous exercise
Li Wang1, Niklas Psilander, Michail Tonkonogi
1GIH, the Swedish School of Sport and Health Sciences, Astrands Laboratory, Stockholm, Sweden.
Medicine and Science in Sports and Exercise
|November 17, 2009
Summary
Both interval exercise (IE) and continuous exercise (CE) similarly boost mitochondrial biogenesis gene expression. However, CE uniquely enhanced downstream targets of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1alpha).
Area of Science:
- Exercise Physiology
- Molecular Biology
- Metabolic Research
Background:
- Mitochondrial biogenesis is crucial for oxidative metabolism.
- The comparative effects of interval exercise (IE) versus continuous exercise (CE) on mitochondrial biogenesis remain debated.
- Understanding gene expression changes provides insight into exercise adaptations.
Purpose of the Study:
- To compare the effects of acute IE and CE on muscle messenger RNA (mRNA) content for genes involved in mitochondrial biogenesis and lipid metabolism.
- To investigate whether exercise intensity or duration is a primary driver of these molecular adaptations.
- To elucidate the differential impact of IE and CE on key regulatory and downstream targets of mitochondrial gene expression.
Main Methods:
- Nine sedentary subjects completed two 90-minute cycling protocols: CE (67% VO2max) and IE (alternating high and low intensity intervals).
- Exercise duration and work performed were matched between protocols.
- Muscle biopsies were collected pre-exercise and 3 hours post-exercise to analyze mRNA expression.
Main Results:
- Both IE and CE induced similar increases in VO2 and heart rate, muscle glycogen reduction, and blood metabolite changes.
- mRNA content for major mitochondrial biogenesis regulators (PGC-1alpha, PGC-1-related coactivator, PPARbeta/delta) and lipid metabolism (PDK4) increased similarly after both protocols.
- CE, but not IE, significantly increased mRNA content for several downstream targets of PGC-1alpha and nuclear respiratory factor 2.
Conclusions:
- When exercise duration and work are equated, IE and CE similarly impact the transcription of genes central to oxidative metabolism.
- CE may elicit a more pronounced transcriptional response in specific downstream targets of PGC-1alpha, suggesting potential differences in adaptive signaling.
- These findings contribute to understanding the nuanced molecular responses to different exercise training modalities.
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