In this episode of the Evolving Performance Podcast, Kevin is joined by Joel Jamieson, one of the most widely cited authorities on conditioning and energy system development in the world. Joel has trained elite combat sport athletes since 2004 and consulted for organizations from the Navy SEALs to teams in the NFL, NBA, MLS, and NCAA. He is the author of Ultimate MMA Conditioning, created the BioForce HRV system, and developed Morpheus, a training platform that uses daily HRV, sleep, and activity data to individualize heart rate zones. They start by separating fitness from conditioning — fitness being the measurable physiological qualities, conditioning being how well those qualities integrate to meet a specific demand. Joel explains why heart rate recovery tells you more about repeat sprint ability than VO2 max, how the aerobic system fuels recovery both between reps and across an entire competitive season, and what zone two training actually is beyond the second band on a heart rate monitor. The conversation also covers why the fear that aerobic work makes athletes slower is largely overstated, the real limits of the interference effect, and why fixed heart rate zones misrepresent a body that changes day to day. This episode offers a clear framework for coaches and athletes looking to build aerobic capacity without sacrificing speed and power, and to understand what actually drives recovery and resilience. Topics Include: Why fitness and conditioning are not the same thingBuilding a performance model to determine what an athlete actually needsWhy VO2 max poorly predicts repeat sprint performanceHeart rate recovery as the most underutilized assessment toolReading heart rate recovery between sparring rounds or practice repsResting heart rate vs. HRV — absolute values or direction of changeThe anaerobic speed reserve and how to field test itHow the aerobic system drives recovery across a competitive seasonWhat zone two actually is, and why percentage-of-max-HR misses itLeft ventricular volume vs. contractile strength, and how to train eachMinimum effective dose for zone two, and why lifting doesn't countWhy aerobic training won't make athletes slowerTempo intervals, high intensity continuous training, and uphill sprintsWhen the interference effect is real and when it isn'tClosing the gap between fitness capacity and game day expressionSleep, nutrition, and mental stress as recovery variablesHow Morpheus shifts heart rate zones based on daily recovery📲 Connect with Joel Jamieson: Instagram: @coachjoeljamieson Morpheus: TrainWithMorpheus.com 8 Weeks Out: 8WeeksOut.com 📩 Contact Kevin: Follow and suggest future guests, topics, and questions: @KevinNeeld 📺 Watch the videos: @NeeldPerformance 🧠 Subscribe to the free newsletter: KevinNeeld.com 📬 Email: KN@KevinNeeld.com ⏱️ Timestamps [00:00:00] Introduction and Guest Background [00:01:00] Episode Overview and Sponsor Highlight [00:05:00] Defining Conditioning vs. Fitness [00:09:05] Assessments and Building a Performance Model [00:11:48] Why VO2 Max Falls Short for Repeat Sprint Ability [00:14:05] Heart Rate Recovery as an Assessment Tool [00:17:35] Resting Heart Rate vs. HRV [00:20:22] The Aerobic System's Role in Repeating Speed and Power [00:23:38] The Anaerobic Speed Reserve and Field Testing [00:25:28] Aerobic Training, Resilience, and Recovery Mechanisms [00:28:52] What Zone Two Training Really Is [00:34:53] Building Heart Size vs. Heart Strength [00:38:30] Minimum Effective Dose for Zone Two [00:41:02] Does Aerobic Training Make Athletes Slower? [00:43:48] Tempo Intervals and High Intensity Continuous Training [00:45:43] The Interference Effect [00:48:12] Closing the Gap Between Capacity and Expression [00:50:30] Readiness, Sleep, and Recovery Factors [00:53:35] Inside Morpheus