Aerobic metabolism prolonged exercise

Exercise performance seems to be greatly affected by the chronic level of physical activity experienced by the animal or Individual. For example, differences In the capacity for prolonged exercise seem obvious between wild and domesticated animals. This Is probably due. In part, to Inherent biochemical differences between the muscles of active and less active species ( 1 ). Muscles of wild animals appear darker than those of their domesticated counterparts ( ). Further, variations In activity patterns due to seasonal change (3 ) or hibernation ( ), are associated with differences In the enzymes related to oxidative metabolism. Thus, In a general sense physical activity seems to be associated with biochemical changes that enhance the muscle s capacity for aerobic metabolism. 

Peripheral artery disease (PAD) patients usually feel leg pain when walking, which is caused by insufficient blood flow to keep up with energy demand. The P MRS data collected in a PAD patient group showed prolonged PCr recovery rate (or time constants) in the calf muscle after exhaustive exercise, suggesting the transition from anaerobic to aerobic energy metabolism is delayed due to impaired oxygen supply or mitochondria fimction caused by atherosclerosis. ... 

The major metabolic fuel for participating in a prolonged aerobic exercise event is which of the following ... 

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