Final answer:
The endurance training adaptation that assists in maintaining acid-base balance during exercise is the increased M4 form of LDH, an enzyme that helps metabolize lactate which is produced during glycolysis.
Step-by-step explanation:
Endurance Training and Acid-Base Balance
Among the given options, the endurance training adaptation that assists in maintaining acid-base balance during exercise is b) increased M4 form of LDH (lactate dehydrogenase). This enzyme plays a significant role in the metabolism of lactate, which is a by-product of anaerobic glycolysis. During endurance exercise, there is an increased demand for energy, and the muscles may rely on glycolysis for quick energy production. This leads to the production of pyruvate and, if oxygen is limited, the conversion of pyruvate to lactate. LDH converts lactate into a form that can be reused in the process of gluconeogenesis or metabolized further in the presence of oxygen, thus contributing to the management of pH levels in the body.
On the other hand, increased mitochondrial volume in skeletal muscle (a) is primarily related to improvements in aerobic metabolism, enabling muscles to generate more ATP using oxygen. Increased lactate production (c) and increased pyruvate formation (d) are both outcomes of heightened glycolytic activity, which would need to be counterbalanced for acid-base homeostasis but do not directly aid in the process.