Research
Hormonal
Resistance exercise induces the expression of PGC-1α4, a splice variant that promotes muscle hypertrophy by inducing IGF1 and repressing myostatin, whereas endurance exercise does not significantly induce this variant.
If your goal is to increase muscle size (hypertrophy), prioritize resistance training (heavy loads, fewer reps). This specific type of exercise triggers the PGC-1α4 pathway, which boosts growth factors like IGF1 and reduces muscle inhibitors like myostatin. Endurance exercise does not trigger this specific growth pathway.
GoodSupportsHIGH confidence
PGC-1α4 expression is induced with resistance exercise protocols (fewer repetitions at high muscle loads aimed at increasing muscle mass) and not with endurance exercise. Skeletal muscle-specific transgenic overexpression of PGC-1α4 results into hypertrophic and stronger mice
Why this rating
Based on transgenic mouse models and human exercise studies cited.
Source
Mitochondrial Quality Control and Muscle Mass Maintenance
Vanina Romanello et al. · Frontiers in Physiology · 2016
DOI 10.3389/fphys.2015.00422
narrative_reviewCited 426×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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