Owhat aspects of metabolic homeostasis promote optimal athletic performance

The answer is lactate homeostasis. Lactic acid accumulates in muscle during high exercise activities due to a high demand for energy in the muscles. Therefore, glucose is broken down anaerobically to produce lactic acid since oxygen cannot be supplied fast enough for complete aerobic respiration. Its accumulation in muscles causes muscle fatigue and post-exercise muscle soreness.

change in breathing rate, heart rate and sweating rate

Explanation:

When an athlete exercises, he/she faces the change in breathing rate, heart rate and sweating rate. This all happens in order to maintain homeostasis.  

Sweating maintains the temperature of the body by evaporating through the skin surface while the increased heart rate causes high speed flow of blood through the body surface to allow dispersal of extra heat generated. While increased breathing rate reduces the chances of anaerobic respiration in muscles thereby causing lactation and pain associated with lactation.