Effects of 7 wk of endurance training on human skeletal muscle metabolism during submaximal exercise

Fifteen minutes of exercise after 7 weeks of endurance training resulted in a decrease in pyruvate dehydrogenase activation from 3.75 +/- 0.48 to 2.65 +/- 0.38 mmol.min(-1).kg wet wt(-1).

• Endurance training may lead to reduced activation of pyruvate dehydrogenase (PDH) during exercise.
• Post-training, lower pyruvate content was observed, decreasing from 0.94 +/- 0.14 to 0.46 +/- 0.03 mmol/kg dry wt.
• A decrease in muscle glycogen breakdown rate was noted, decreasing from 13.22 +/- 1.01 to 7.36 +/- 1.26 mmol.min(-1).kg dry wt(-1).
• Smaller net increases in muscle free ADP and inorganic phosphate suggest a regulatory shift in glycogen phosphorylase activation.
• The findings indicate that multiple signals may coordinate the regulation of key enzymes in carbohydrate metabolism following endurance training.

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