Decrease in Akt/PKB signalling in human skeletal muscle by resistance exercise.

Area of Science:

• Exercise Physiology
• Molecular Biology
• Biochemistry

Background:

• Understanding cellular adaptations to exercise is crucial for optimizing training protocols.
• The Akt/PKB and MAPK pathways are critical regulators of cellular growth and adaptation.
• Investigating protein phosphorylation provides insights into signaling events post-exercise.

Purpose of the Study:

• To analyze the effects of high-intensity resistance exercise on protein phosphorylation in adaptive signaling pathways.
• To examine the immediate and delayed effects on the Akt/PKB and MAPK pathways.

Main Methods:

• Nine healthy young men performed 10 sets of 10 leg extensions at 80% of 1-RM.
• Muscle biopsies were collected from vastus lateralis at rest, immediately post-exercise, and 24 hours post-exercise.
• Phosphorylation states of key proteins (Akt/PKB, 4E-BP1, p70(s6k), p38, ERK1/2) were analyzed.

Main Results:

• Immediately post-exercise, Akt/PKB and 4E-BP1 phosphorylation decreased significantly (-60 to -90%).
• Conversely, p70(s6k), p38, and ERK1/2 phosphorylation increased substantially (10- to 50-fold).
• At 24 hours, Akt/PKB phosphorylation remained depressed, while p70(s6k) and ERK1/2 phosphorylation were elevated.

Conclusions:

• High-intensity resistance exercise in a fasted state differentially regulates Akt/PKB and MAPK signaling.
• The findings suggest an inhibition of Akt/PKB and 4E-BP1 signaling with a concurrent augmentation of MAPK and p70(s6k) signaling.
• These molecular responses provide insights into the complex adaptive processes following resistance exercise.