The way muscle is built is important for the way that energy is created in the body. For example, there are two different types of muscle fiber: fast-twitch fibers and slow-twitch fibers. Just like human sprinters contain mostly fast-twitch fibers, necessary for high impact exercise, so do cheetahs.

Fast-witch fibers work with high glycolytic enzyme activity due to anaerobic respiration. This supports a higher ATP turnover in the muscles for sprinters like the cheetah that uses up a lot of energy. Slow-twitch fibers are used for endurance with high levels of myoglobin to store oxygen to be used when it is really needed (Williams et al., 1997). 

It was found that fast-twitch fibers made up over 60% of fibers in the gastrocnemius and 83% in the vastus lateralis (two different muscles) As seen in Table 1, there were greater amounts of FG (fast glycolytic) fibers and FOG (fast oxidative glycolytic) fibers than SO (slow-twitch oxidative) fibers. This shows that cheetahs’ skeletal muscles primarily use anaerobic types of metabolism (Williams et al., 1997).   

Table 1

Table Adapted from Williams et al., 1997.

Anaerobic Metabolism

High impact exercise uses up all of the oxygen so muscle cells have to rely on reactions that do not use oxygen to create energy. Glycolysis is how the cheetah is able to create energy. If you look at this link to glycolysis, you can see that glucose is broken down by enzymes into 2 pyruvate in order to form two ATP. Lactic acid also happens to form from the 2 pyruvate as a waste product (Cellular Metabolism and Fermentation).

This process produces waste though, and too much lactic acid in the muscles is not good for the body. Too much lactic acid along with a low supply of oxygen in the blood causes the cheetah to take frequent breaks from sprinting to recuperate (Williams et al., 1997).

Enzyme Activity

The fast-twitch fibers in the muscle play an imporatant role in the use of sprinting, but the enzyme capacities in the skeletal muscle play an even larger role! High amounts of anaerobic, LDH and PK, enzymes and low amounts of aerobic, CS and HOAD, enzymes were found in the muscles (as seen in Table 2). The anaerobic enzymes, LDH and PK allow for much greater glycogen use in the cheetah. Through glycogenolysis, glycogen can be broken down into glucose which in turn can create energy for the cheetah (Williams et al., 1997).

Table 2

Table Adapted from Williams et al., 1997.