Endurance training increases skeletal muscle lactate transport

Area of Science:

• Exercise Physiology
• Skeletal Muscle Biology
• Biochemistry

Background:

• Endurance training reduces skeletal muscle lactate accumulation.
• Mechanisms include increased oxidative capacity, reduced lactate production, and enhanced lactate clearance.
• Muscle membrane lactate transport is crucial for lactate clearance and may be affected by training.

Purpose of the Study:

• To investigate the effect of endurance training on lactate transport capacity in rat skeletal muscle sarcolemmal membranes.
• To determine if training alters the kinetics of lactate transport.

Main Methods:

• Skeletal muscle sarcolemmal vesicles were isolated from endurance-trained and sedentary rats.
• Lactate transport was measured using the zero-trans assay with varying L-lactate concentrations (1 mM and 50 mM).
• Training involved 6 weeks of progressive treadmill exercise.

Main Results:

• Lactate transport increased by 59.4% at low L-lactate concentrations (1 mM) in trained rats (P < 0.05).
• No significant change in lactate transport was observed at high L-lactate concentrations (50 mM) (P > 0.05).

Conclusions:

• Endurance training enhances the maximal capacity for lactate transport in skeletal muscle membranes at physiological lactate levels.
• The findings suggest an alteration in the Michaelis-Menten constant (Km) rather than the maximal velocity (Vmax) of the lactate transport system.
• Specific changes in lactate transporter isoforms may contribute to improved lactate handling post-training.