Question

Which of the following would you expect to see in abundance in the muscles of a sprinter?

a.) Myoglobin

b.) Proteins that form part of the electron transport chain

c.) Lactate dehydrogenase

d.) Mitochondria

Answer 1

Which of the following would you expect to see in abundance in the muscles of a sprinter?

Answer : c) Lactate dehydrogenase.

Explanation : Sprinting is a form of running in which a short distance is covered in a limited period of time. As this requires greater force of muscular contraction for lesser duration of time, it is dependent mainly on the activites of fast twitch fibers.

Sprinters are mainly dependent on aerobic glycolysis energy requirements through fast twitch fibers. In aerobic glycolysis, glucose is converted into pyruvate. This pyruvate is later converted into Acetyl CoA with the help of the enzyme pyruvate dehydrogenase. A total of 7 ATP molecules are produced through one molecule of glucose in aerobic glycolysis along with NDPH (reduced nicotinamide adenine dinucleotide).

Fast twitch fibers have comparatively less mitochondria and myoglobin and hence they tend to undergo fatigue within short duration of time. The fatigue is mainly due to the accumulation of lactic acid in the muscles. Thus, fast twitch fibers are best suited to perform intense activities for shorter duration of time like sprinting.

Abundant mitochondria and myoglobin are the features of slow twitch fibers (type I fibers) which are required to perform less intense activities for longer duration of time like endurance exercises and running a marathon. They can sustain their activites for longer duration of time as they are dependent on aerobic respiration for glucose utilisation which is more effective way of glucose utilisation.

As there is no lactic acid production, slow twitch fibers can work for longer duration of time without getting fatigued. Hence, they are best suited for endurance exercises.

Thus, the enzyme lactate dehydrogenase is found in abundance in the muscles of a sprinter for better utilisation of glucose through glycolysis and perform intense activities for shorter duration of time. Whereas, the mitochondriamitochondria and myoglobin are found in abundance in the muscles of a marathon runner or endurance trainer, as they are required to perform slow and sustained muscular contraction for longer duration of time without getting fatigued.