Substantial working muscle glycerol turnover during two-legged cycle ergometry

Area of Science:

• Exercise Physiology
• Metabolic Biochemistry

Background:

• Skeletal muscle triacylglyceride turnover is crucial for energy metabolism.
• Understanding glycerol exchange provides insights into this process.

Purpose of the Study:

• To evaluate the effects of exercise and endurance training on leg triacylglyceride turnover.
• To assess glycerol exchange as an indicator of triacylglyceride metabolism.

Main Methods:

• Combined tracer and arteriovenous balance techniques using [(2)H(5)]glycerol infusion.
• Measured leg blood flow and femoral arteriovenous sampling in eight men.
• Determined leg glycerol turnover at rest and during exercise before and after 9 weeks of endurance training.

Main Results:

• Endurance training increased peak oxygen consumption (Vo(2peak)) by 15%.
• Tracer-measured leg glycerol uptake and release occurred simultaneously at rest and during exercise.
• Leg glycerol turnover was significantly augmented during exercise bouts.
• Neither exercise intensity nor endurance training affected overall leg glycerol turnover.

Conclusions:

• Simultaneous leg glycerol uptake and release indicate active leg triacylglyceride turnover.
• Exercise substantially augments leg glycerol turnover.
• Leg glycerol turnover is a dynamic process occurring even with minimal net exchange.