Final answer:
Improved fitness allows for higher intensity exercise before the lactate threshold is reached. Lactate build-up is just one component of muscle fatigue influenced by various factors.
Step-by-step explanation:
Improved fitness allows you to exercise at higher intensities before the abrupt build-up of metabolic acids referred to as the Lactate Threshold.
Elevated muscle and blood lactate concentrations are a natural consequence of any physical exertion. The effectiveness of anaerobic activity can be improved through training. Fatigue, or muscle failure, is influenced by various factors such as energy availability, oxygen delivery, and psychological factors, not just changes to lactate concentration.