Myocellular triacylglycerol breakdown in females but not in males during exercise

Am J Physiol Endocrinol Metab. 2002 Mar;282(3):E634-42. doi: 10.1152/ajpendo.00078.2001.

Abstract

The resting content and use of myocellular triacylglycerol (MCTG) during 90 min of submaximal exercise [60% of peak oxygen uptake (VO(2 peak))] were studied in 21 eumenorrheic female and 21 male subjects at different training levels [untrained (UT), moderately trained (MT), and endurance trained (END)]. Males and females were matched according to their VO(2 peak) expressed relative to lean body mass, physical activity level, and training history. All subjects ingested the same controlled diet for 8 days, and all females were tested in the midfollicular phase of the menstrual cycle. Resting MCTG, measured with the muscle biopsy technique, averaged 48.4 +/- 4.2, 48.5 +/- 8.4, and 52.2 +/- 5.8 mmol/kg dry wt in UT, MT, and END females, respectively, and 34.1 +/- 4.9, 31.6 +/- 3.3, and 38.4 +/- 3.0 mmol/kg dry wt in UT, MT, and END males, respectively (P < 0.001, females vs. males in all groups). Exercise decreased MCTG content in the female subjects by an average of 25%, regardless of training status, whereas in the male groups MCTG content was unaffected by exercise. The arterial plasma insulin concentration was higher (P < 0.05) and the arterial plasma epinephrine concentration was lower (P < 0.05) in the females than in the males at rest and during exercise. MCTG use was correlated to the resting concentration of MCTG (P < 0.001). We conclude that resting content and use of MCTG during exercise are related to gender and furthermore are independent of training status.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Arteries
  • Biopsy
  • Body Composition
  • Diet
  • Dietary Carbohydrates / administration & dosage
  • Dietary Fats / administration & dosage
  • Energy Intake
  • Epinephrine / blood
  • Estradiol / blood
  • Exercise / physiology*
  • Female
  • Follicular Phase
  • Humans
  • Insulin / blood
  • Male
  • Muscle Fibers, Skeletal / ultrastructure
  • Muscle, Skeletal / metabolism*
  • Muscle, Skeletal / ultrastructure
  • Norepinephrine / blood
  • Oxygen Consumption
  • Physical Endurance
  • Physical Fitness
  • Progesterone / blood
  • Pulmonary Gas Exchange
  • Sex Characteristics*
  • Triglycerides / metabolism*

Substances

  • Dietary Carbohydrates
  • Dietary Fats
  • Insulin
  • Triglycerides
  • Progesterone
  • Estradiol
  • Norepinephrine
  • Epinephrine