Endurance training increases gluconeogenesis during rest and exercise in men

Area of Science:

• Exercise Physiology
• Metabolic Adaptations

Background:

• Gluconeogenesis (GNG) is crucial for maintaining blood glucose homeostasis.
• The impact of endurance training on GNG during rest and exercise requires further elucidation.

Purpose of the Study:

• To investigate the hypothesis that endurance training increases gluconeogenesis during rest and exercise.
• To quantify the changes in GNG rates before and after a structured endurance training program.

Main Methods:

• Utilized stable isotope tracers ([6,6-(2)H]glucose and [3-(13)C]lactate) to measure glucose turnover and lactate incorporation into glucose.
• Assessed glucose production and lactate kinetics during graded cycle ergometry (45% and 65% peak O(2) consumption) before and after a 9-week training intervention.
• Measured arterial glucose and lactate concentrations at rest and during exercise.

Main Results:

• Endurance training significantly increased the percentage of glucose rate of appearance from GNG at rest (from 1.98% to 5.45%) and during exercise (to 7.6% at absolute workload and 6.1% at relative intensity).
• The absolute rate of gluconeogenesis more than doubled at rest (0.11 to 0.24 mg·kg(-1)·min(-1)) and nearly tripled during exercise (0.24 to 0.71 mg·kg(-1)·min(-1) at absolute workload, and 0.75 mg·kg(-1)·min(-1) at relative intensity).
• Arterial lactate concentrations during exercise were reduced post-training compared to pre-training levels at the same absolute workload.

Conclusions:

• Endurance training enhances gluconeogenesis at rest and during exercise.
• This adaptive increase in glucose production contributes to improved metabolic regulation during physical activity.
• The findings support the role of increased gluconeogenesis as a key adaptation to endurance training.