Gender: Does Gender Affect Fuel Stores and Fuel Use?
|
Male |
Look at these two skiers,
one female and one male. Do they store fuel and use fuel differently
during exercise?
|
Female |
This table illustrates the difference in muscle glycogen stores relative to gender and carbohydrate content of the diet. Are these differences due solely to the fact that the reference female is smaller in body size and body weight than the reference man?
Data is not available to fully answer that question. However, one recent study (Tarnopolsky, 1995) reported that women athletes consuming a moderately high carbohydrate diet, unlike similarly trained and nourished men, did not increase their muscle glycogen content in response to a carbohydrate loading dietary regimen. Regarding the quantity of fat stores, women exceed men. Although elite endurance skiers of both genders are very lean, typical body composition ranges of US Olympic trained cross country skiers are below 7% body fat for men and below 13% body fat for females (Luke Bodensteiner, 1997, personal communication).
Traditionally most exercise science studies in humans have used males as subjects. Although that practice has changed somewhat, little data exists regarding differences in fuel use between males and females. However, studies (Tarnopolsky, 1990; Phillips, 1993) have indicated that during exercise performed at moderate intensities for long durations, women rely more on fat for fuel and less on carbohydrate and protein than do similarly trained and nourished men.
The mechanism responsible for the
enhanced fat oxidation during exercise observed in women compared with men
is not known but may involve the effects of estrogen and other hormones. Clearly,
this area deserves further research. Future findings could affect nutrition
recommendations provided to female athletes and other physically active women.
