Global and regional left ventricular circumferential strain during incremental cycling and isometric knee extension exercise

Abstract

Background: The objective of this study was to investigate left ventricular (LV) circumferential strain responses to incremental cycling and isometric knee extension exercises. Methods: Twenty-six healthy male participants (age = 30 ± 6 years) were used to study LV global (GCS) and regional circumferential strain at the apex (ACS) and base (BCS) during incremental cycling at 30% and 60% work rate maximum (Wmax) and short-duration (15 seconds contractions) isometric knee extensions at 40% and 75% maximum voluntary contraction (MVC) using two-dimensional speckle tracking echocardiography. Results: During cycling (n = 22), GCS increased progressively from rest to 60% Wmax (−22.85 ± 3.26% to −29.87 ± 2.59%, P .05). Conclusion: Global circumferential strain increased stepwise during incremental cycling, mediated by the apex with trivial changes at the base. In contrast, GCS decreased during the isometric knee extension to 40% MVC and then plateaued, due to decreased BCS as ACS was maintained. A novel finding is that the GCS response appears to be exercise modality dependant and is the consequence of region-specific changes