Cycling coach Marinus Petersen returns to revisit bicarbonate supplementation tips and to discuss training around the first lactate threshold (LT1).  Petersen shares his views on intensity domains, the importance of LT1, and how he incorporates this concept into his coaching. * Bicarb Neutralization: A discussion on whether mixing bicarbonate with acidic substances like jelly or jam neutralizes its effectiveness. Petersen argues that the acidity of the stomach far outweighs any pre-ingestion neutralization. * Practicality of Bicarb Use: The challenges of using bicarb in conjunction with a regular work schedule, and tips for timing bicarb intake around workouts. * Importance of LT1: Petersen considers LT1 the most critical metric for an athlete due to the significant difference in fatigue levels when training above or below it. * Measuring LT1: Lactate testing to accurately determine LT1, using 10-minute stages with 10-watt increments to pinpoint the threshold. * Coaching Considerations: A discussion on the challenges of balancing structured training with the enjoyment of riding, allowing flexibility in training as long as the intensity of endurance rides stays below LT1. * Sub-LT1 Work: Considerations for aerobic training at very long durations at well below LT1 vs. relatively shorter bouts just below LT1.