In this episode of Fast Physiology on the Critical Oxygen podcast, I am joined again by Coach Dave Schell where we discuss sweet spot or gray zone training. We start by defining sweet spot training as high zone three to low zone four training, which is has been used to accumulate training stress for time crunched athletes while also improving performance. We explore the history of sweet spot training and its popularity among time-crunched athletes. The conversation also delves into the drawbacks of excessive sweet spot training and the importance of periodization and specificity in training. The episode concludes with key takeaways, emphasizing the need for a balanced approach to training and the importance of individualization. TAKEAWAYS 1) Sweet spot training is define as below threshold but in the upper portion of Zone 3. 2) It could be useful to improve sport specific efficiency and fitness. 3) Sweet Spot Training is attractive to many time-crunched athletes but it shouldn't be your only training intensity! 4) Cyclists may be able to get away with more sweet spot training, but as a runner be cautious of doing too much zone 3 training! 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 Dave on Instagram - https://www.instagram.com/kaizenendurance/ Interested in Gravel or Mountain Bike Coach? Head to Dave's website - https://www.kaizenendurance.coach/ CHAPTERS 00:00 Introduction 01:13 Definition of Sweet Spot Training 03:12 History of Sweet Spot Training 04:06 Benefits and Drawbacks of Sweet Spot Training 05:59 Gray Zone Training in Running 07:24 The Role of Sweet Spot Training in Race Preparation 09:49 The Relationship Between Fatigue and Physiological Adaptation 11:18 Debate on the Effectiveness of Sweet Spot Training 12:21 The Importance of Volume and Intensity in Training 15:40 The Role of Specificity in Training 18:32 Takeaways