The significance of lactate threshold in endurance training lies in its role as an indicator of an athlete's ability to sustain high-intensity efforts without fatigue. It represents the exercise intensity at which lactate begins to accumulate in the bloodstream, signifying a shift from predominantly aerobic metabolism to anaerobic metabolism. Training at or near this threshold can improve an athlete’s endurance performance by increasing their ability to work at higher intensities for longer durations, thereby enhancing overall athletic capabilities.