Association between exercise intensity and renal blood flow evaluated using ultrasound echo

Area of Science:

• Exercise Physiology
• Renal Physiology
• Cardiovascular Regulation

Background:

• High-intensity exercise can decrease renal blood flow (RBF), potentially impairing kidney function.
• Non-invasive RBF measurement is now feasible with advanced technology.
• This study investigates RBF changes during varying exercise intensities.

Purpose of the Study:

• To examine how different exercise intensities affect renal blood flow (RBF).
• To utilize non-invasive ultrasound echo technology for RBF measurement.
• To explore the relationship between exercise intensity, lactate levels, and RBF.

Main Methods:

• Eight healthy men performed incremental and multi-stage bicycle ergometer tests.
• Renal blood flow (RBF) was measured using ultrasound echo at rest and post-exercise.
• Catheterization assessed sympathetic nervous system involvement in RBF regulation.

Main Results:

• RBF decreased by 51% after maximal exercise in Study 1.
• Significant RBF reduction (31%) occurred at 100% lactate acid breaking point (LaBP) intensity in Study 2.
• No significant RBF decrease was observed until 80% LaBP.

Conclusions:

• Renal blood flow (RBF) remains stable until 80% of the lactate acid breaking point (LaBP).
• RBF reduction above LaBP correlates with increased blood lactate levels.
• Decreased cross-sectional area, not flow velocity, primarily causes RBF reduction during intense exercise.