In this episode of the Critical Oxygen podcast, continuing guest host Aaron Geiser and I answer listener questions and discuss various topics related to endurance training. We cover the benefits and timing of cold water immersion, the duration of zone two training for masters athletes, and the role of genetics in performance for masters athletes. We emphasize the importance of individualized training, consistency, and progressive overload in improving endurance over time. In this episode, we discuss nutrition and recovery for aging athletes, important blood markers to track, and the best home test protocol for athletes with just a power meter and a heart rate monitor. TAKEAWAYS 1) Cold water immersion can have benefits for recovery and performance, but timing and context are important factors to consider. 2) Zone two training duration for masters athletes should be based on individual factors and training background, rather than age alone. 3) Fasting during zone two training may not be necessary, but ensuring adequate calorie intake throughout the day is important for performance and recovery. 4) Genetics may play a role in performance potential, but consistent training, nutrition, and stress management can help individuals reach their personal potential. 5) Aging athletes have different nutritional needs and should focus on increased protein, recovery, mobility work, stability work, and strength work. 6) The best home test protocol for athletes with just a power meter and a heart rate monitor is to do workouts that are close to zone two, threshold, and VO2 max, and measure power and heart rate over time. Enjoy! Enjoying these podcasts, subscribe to get notified when new episodes are released. If you have a question or topic you want us to address, leave a comment! Follow Phil on Instagram - https://www.instagram.com/criticalo2 Follow Aaron on Instagram - https://www.instagram.com/triageiser/ CHAPTERS 00:00 Introduction 01:31 Listener questions and answers 04:18 Experience with cold tub and ice baths 05:45 Factors to consider in cold water immersion 08:09 Timing and benefits of cold water immersion 10:21 Context and timing of cold water immersion 11:47 Training questions for masters athletes 12:19 Duration and fasting in zone two training 27:53 Improving endurance for masters athletes 28:51 Nutrition and Recovery for Aging Athletes 31:33 Important Blood Markers to Track 47:48 Best Home Test Protocol for Athletes