After a sprint exercise the AMP/ATP ratio is remarkably increased, however the activity of AMP-activated protein kinase (AMPK) is decreased or unchanged.

Aim: to explore a potential mechanism that could explain this lack of activation of AMPKa, though a concomitant phosphorylation of Ser^485/491 in the catalytic a1/a2-subunits, which could blunt Thr¹⁷²-AMPKa phosphorylation.

Methods: 

Ser⁴⁷³-Akt, Ser⁴⁸⁵-AMPKa1/Ser⁴⁹¹-AMPKa2 and Thr¹⁷²-AMPKa phosphorylation levels in skeletal muscle were determined by immunoblotting in fifteen young healthy men in response to a 30 s sprint exercise (Wingate test). Subjects were randomly distributed into two groups. One group exercised under fasting conditions (n=7, C), and the other ingested 75g of glucose (G) one hour before exercising (n=8).

Results: 

sprint exercise elicited an immediate Ser⁴⁷³-Akt phosphorylation and Ser⁴⁹¹-AMPKa2 phosphorylation. During the recovery process Ser⁴⁷³-Akt phosphorylation remained elevated during 120 min in C and 30 min in G. Thirty min after the sprint, Ser⁴⁹¹-AMPKa2 phosphorylation was reduced by 33% in C and was increased 3-fold in G. At the same time, Thr¹⁷²-AMPKa phosphorylation was increased by five-fold (P<0.05) in C, whereas was unchanged in G. In G, there was a relationship between Ser⁴⁷³-Akt and Ser⁴⁸⁵-AMPKa1/Ser⁴⁹¹-AMPKa2 phosphorylation (r=0.86, P< 0.05).

Conclusion: 

sprint exercise elicits an immediate Ser⁴⁷³-Akt phosphorylation and Ser⁴⁹¹-AMPKa2 phosphorylation, and the latter could be responsible for blunting Thr¹⁷²-AMPKa phosphorylation 30 min after the sprints performed 60 min following the ingestion of 75 g of glucose.