Research

Hormonal

Intense cycling exercise activates MAPK (ERK1/2, p38) and AMPK signaling pathways in skeletal muscle, leading to downstream phosphorylation of MSK1 and histone H3, with untrained individuals exhibiting a greater signaling response than highly trained athletes at the same relative intensity.

If you are a trained athlete, standard moderate-intensity exercise may not trigger the same level of cellular signaling (MAPK/AMPK) as it does for beginners. To maintain these specific adaptive signals, you likely need to increase the intensity or volume of your training, as your muscles have adapted to be more resistant to these stimuli.

GoodSupportsHIGH confidence
In conclusion, intense cycling exercise in subjects with a prolonged history of endurance training increases MAPK signalling to the downstream targets MSK1 and histone H3 and isoform-specific AMPK signalling to ACC. Importantly, exercise-induced signalling responses were greater in untrained men, even at the same relative exercise intensity, suggesting muscle from previously well-trained individuals requires a greater stimulus to activate signal transduction via these pathways.
Mei Yu et al. · The Journal of Physiology · 2003

Why this rating

Controlled human study with rigorous biochemical assays (immunoblot, immune complex assay) and statistical significance (P < 0.05), though small sample size (n=10).

Source

Metabolic and mitogenic signal transduction in human skeletal muscle after intense cycling exercise

Mei Yu et al. · The Journal of Physiology · 2003

DOI 10.1113/jphysiol.2002.034223

mechanism_only · n=10Cited 159×
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DOI resolved against Crossref · corpus check 2026-06-10

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