In this episode of the Athletes Compass podcast, hosts Paul Laursen, Marjaana Rakai, and Paul Warloski explore how the heart functions as a major limiter of VO2 max and endurance performance. They break down the components of cardiac output, discuss genetic ceilings and the effects of aging on heart rate, and offer practical training strategies to maximize cardiac function. Drawing on scientific literature and real-world athlete examples, the team gives actionable advice for improving VO2 max—even for everyday athletes.

• The heart, especially cardiac output, is often the primary limiter of VO2 max.
• VO2 max = cardiac output (stroke volume × heart rate). Both factors matter.
• Aging reduces max heart rate—roughly 1 beat per year—which can lower VO2 max.
• Genetics play a role, but consistent, individualized training has a big impact.
• High training volume improves efficiency and threshold; HIIT boosts VO2 max ceiling.
• Training zones differ across sports due to body position and demands (e.g., swimming vs. running).
• Individual variability in heart rate response and adaptation is normal.
• Accurate zone setting requires solid data: races, FTP tests, 5K runs, etc.

• Paul Warloski - Simple Endurance Coaching
• Marjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.

In this episode, Paul Laursen, Paul Warloski, and Marjaana Rakai tackle one of the least understood but critically important VO2 max limiters: the lungs. From the phenomenon of exercise-induced arterial hypoxemia (EIH) affecting 50% of elite athletes to practical methods for respiratory muscle training, the trio breaks down the science of lung function and its real impact on athletic performance. Whether you're curious about lung size, high-performance breathing tools, or simply how to get more oxygen into your bloodstream, this episode offers actionable insights and an engaging discussion around a key pillar of endurance capacity.

• Lung function can limit VO2 max, especially in elite athletes experiencing EIH.
• Environmental irritants like smoke and pollution can compound oxygen saturation issues.
• Four key mechanisms cause EIH: ventilation-perfusion mismatch, high cardiac output speed, physiological shunting, and alveolar hypoventilation.
• Training respiratory muscles can reduce the impact of EIH and improve performance.
• Tools like the Breathe Way Better bag and PowerBreathe help train lung musculature.
• Lung size correlates with body size and can impact VO2 max, especially in smaller-stature individuals.
• Women are more likely to experience EIH due to generally smaller lungs.
• VO2 max improvements also aid in submaximal performance by increasing efficiency.

• Paul Warloski - Simple Endurance Coaching
• Marjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.

In this episode of the Athlete’s Compass, the team—Paul Warloski, Dr. Paul Laursen, and Marjaana Rakai—breaks down VO2 max: what it really means, why it's relevant for every endurance athlete (not just the elites), and how it connects to performance, recovery, and long-term health. They explore how training, genetics, testing accuracy, and strength work all influence VO2 max, and offer actionable strategies to improve it at any level. Whether you're chasing PRs or aiming for a healthier life, understanding your VO2 max can be a game changer.

• VO2 max = maximal oxygen uptake, a key indicator of endurance and longevity.
• It’s not just for elite athletes—your health span and performance depend on it too.
• Four main limiters: lungs, blood’s oxygen-carrying capacity, heart function, and muscle oxygen uptake.
• Genetics play a role (~50%), but training can greatly improve VO2 max.
• Tools like Garmin, metabolic carts, and VO2 Master provide various levels of measurement accuracy.
• Zone 1 and 2 training build the aerobic base necessary for VO2 max gains.
• Strength training enhances muscular power and helps reach VO2 max potential.
• Heat training ("poor man's altitude") boosts plasma volume and aids adaptation.

• Paul Warloski - Simple Endurance Coaching
• Marjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.

In this episode of the Athletes Compass podcast, Paul Warloski, Marjaana Rakai, and Dr. Paul Laursen tackle one of the most hotly debated topics in endurance sports: strength training. They break down why lifting heavy won’t make you bulky but will make you a more efficient, resilient, and injury-resistant athlete. With practical advice for beginners to elites, the team covers the best types of exercises, how to progress safely, scheduling strength work around endurance training, and the critical role strength plays in aging well and avoiding long-term injuries. It’s part science, part coaching insight, and all about helping everyday athletes train smarter.

• Strength training doesn't bulk you up when combined with endurance training.
• Benefits include neuromuscular coordination, tendon stiffness, and greater fatigue resistance.
• Women benefit significantly in terms of bone density and aging well.
• Start with bodyweight and build up to heavy lifting as technique improves.
• Focus on six movement patterns: hip hinge, squat, chest push/pull, shoulder push/pull, and core.
• Don’t neglect mobility and rehab work, especially around weak links.
• One to three strength sessions per week depending on the season and training load.
• Doing strength and high-intensity workouts on the same day may improve performance and recovery.
• Consistency matters more than perfection — short sessions are better than none.

• Paul Warloski - Simple Endurance Coaching
• Marjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.

In this episode of The Athletes Compass, Paul Laursen, Marjaana Rakai, and Paul Warloski tackle the most overlooked but pivotal phase of race performance—race week. They break down everything from tapering and travel to gear choices, mindset shifts, and even the science of sleep. With personal stories, cautionary tales, and practical strategies, this episode is the ultimate pre-race briefing for any endurance athlete. Learn how to stay sharp, avoid race-day disasters, and show up calm, confident, and ready to roll.

• Mindset matters more than muscles during race week.
• Visualization is a powerful tool, but overdoing it can cause tension.
• Pacing is everything—starting too fast can ruin your race.
• No new gear, food, or routines on race day. Ever.
• Sleep the week before matters more than the night before the race.
• Make checklists to reduce stress and avoid forgetting essentials.
• Gratitude reframes pre-race nerves into positive energy.
• Support others on the course—the energy you give is the energy you get.

• Paul Warloski - Simple Endurance Coaching
• Marjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.

In Episode 70 of The Athletes Compass, hosts Paul Warloski, Dr. Paul Laursen, and Marjaana Rakai bust major endurance training myths with science-backed insights. From the ineffectiveness of sodium supplementation during exercise to the power of maintaining blood glucose over muscle glycogen, this episode is packed with paradigm-shifting ideas. They also explore fasted training, metabolic flexibility, and why fat is the endurance athlete's forever fuel. Listeners get a masterclass in power profiling, testing methodologies, and how to optimize training for individual physiology. It’s endurance science with a practical edge.

• Sodium During Exercise Is Overrated: No scientific evidence supports sodium supplementation during exercise to prevent cramps, dehydration, or improve performance.
• Power Profile Testing > Ramp Tests: The Athletica power profile provides broader insight into an athlete’s anaerobic and aerobic capacities.
• Short Intervals for Twitchy Athletes: Short VO2 max intervals are more effective for sprinter-type athletes than long intervals.
• Critical Power Curve Guides Training Zones: Accurate power profiling helps set effective training zones for peak performance.
• Blood Glucose Trumps Muscle Glycogen: New research shows maintaining blood glucose may be more critical for endurance than glycogen stores.
• Fasted Training Builds Fat Adaptation: With consistency, athletes can train the body to become metabolically flexible and use fat efficiently.
• Insulin Regulates Fat Usage: Lower insulin levels from low-carb diets promote fat burning and intramuscular fat storage.
• Fat Is a Superior Long-Term Fuel: At 9 kcal/g, fat provides longer-lasting energy than carbohydrates.

• Paul Warloski - Simple Endurance Coaching
• Marjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.

This episode of The Athletes Compass explores the role of heat training in endurance performance. Dr. Paul Laursen, Marjaana Rakai, and Paul Warloski discuss how controlled heat exposure leads to increased plasma volume, red blood cell production, and overall endurance gains—similar to the effects of altitude training. They also provide practical tips on integrating heat sessions into training, balancing active and passive heat exposure, and avoiding potential risks. If you're training for a hot race or simply looking for a new performance edge, this episode will challenge your perspective on heat adaptation.

• Heat training expands plasma volume first, triggering an increase in red blood cell count—a physiological boost similar to altitude training.
• One to three heat sessions per week can create meaningful adaptation, with regularity being key to maintaining benefits.
• Beginners should start with lower-intensity aerobic sessions, while experienced athletes may combine heat training with high-intensity workouts.
• Passive heat exposure (sauna, hot tub) complements active heat training and aids in adaptation.
• Heat training should be progressive—gradual exposure over time builds tolerance and reduces risk.
• Overheating can be dangerous—athletes should have cooling strategies in place (ice baths, cold showers) to recover efficiently.
• Elite athletes like Christian Blumenfeld used extreme heat training for Olympic success, but it’s crucial to adapt it to personal limits.

• Paul Warloski - Simple Endurance Coaching
• Marjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.

This episode of The Athletes Compass explores the evolution of virtual cycling with Robbie Ventura and John Nichols from Velocity Cycling. Originally born out of necessity during the pandemic, Velocity has grown into a dynamic training platform that enhances real-time coaching, skill development, and community engagement. Robbie and John share their journey from struggling to keep their coaching business alive to developing a cutting-edge solution that empowers athletes and coaches alike. They discuss the importance of live coaching, skill-based training, and fostering athlete communities, ensuring that training isn't just about hitting power targets—it's about learning, improving, and staying engaged.

• Velocity Cycling was created out of necessity during the pandemic when in-person training facilities shut down.
• The platform provides live, interactive coaching, making virtual training more engaging and educational.
• Velocity emphasizes skill development, not just raw power output, helping cyclists learn efficiency, gear shifting, and terrain adaptation.
• Coaching matters—athletes perform better with guidance, real-time feedback, and motivation from both coaches and peers.
• Gamification and community building keep athletes engaged and push them to improve.
• Coaches can now train multiple athletes effectively online, reducing overhead costs while increasing accessibility.
• Future developments include a companion app for real-time adjustments and more integration with athlete data.

• Paul Warloski - Simple Endurance Coaching
• Athletica x Velocity Integration
• Marjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.

In this episode of The Athletes Compass, Paul Laursen, Marjaana Rakai, and Paul Warloski tackle listener questions on endurance training. They discuss whether workout order affects performance, the role of strength training in triathlon prep, and how to handle missed workouts. They also break down the science behind carbohydrate fueling, questioning the necessity of high-carb intake for endurance athletes. Finally, they explore whether power pedals are worth the investment and how they can enhance outdoor training. Packed with practical advice, this episode is a must-listen for time-crunched athletes looking to optimize their performance.

• Workout Order: While ideal race simulations are beneficial, the most important thing is getting the work done in a way that fits your schedule.
• Strength Training Placement: The most crucial session should come first, but strength work can fit anywhere based on availability.
• Missed Workouts: Moving sessions around is fine, but be mindful of not stacking too many hard workouts together.
• Carbohydrate Fueling: Sugar isn’t always necessary. A small amount of natural carbs (like bananas or trail mix) can be enough for endurance training.
• Context Over Content: Training plans should be adapted to the individual’s needs, experience level, and goals.
• Power Meters: A useful investment for pacing, data tracking, and improving training efficiency—especially for outdoor cycling.

• Paul Warloski - Simple Endurance Coaching
• Marjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.

This episode of The Athletes Compass Podcast explores two key listener questions: how to train effectively during Ramadan while fasting and how to navigate the ongoing debate around endurance nutrition. Dr. Paul Laursen, Marjaana Rakai, and Paul Warloski provide insights on scheduling workouts around fasting, maintaining energy levels, and managing hydration and recovery. They also discuss the latest research on low-carb versus high-carb diets, debunk the myth of the post-workout anabolic window, and break down which supplements actually improve endurance performance. Whether you're an Ironman athlete or just looking for smarter ways to fuel and train, this episode offers practical takeaways for long-term success.

• Training During Ramadan: Low-intensity sessions in the morning, higher intensity workouts closer to Iftar to optimize fueling and recovery.
• Metabolic Adaptation: Fasting encourages fat oxidation and ketone utilization, which can benefit endurance athletes.
• Balancing Sleep and Social Commitments: Late-night training may impact sleep, requiring adjustments to training plans.
• Low-Carb vs. High-Carb Nutrition: A major study found no significant difference in performance between the two approaches.
• The Best Supplements for Endurance Athletes: Creatine, caffeine, and protein powders are among the most effective, while beta-alanine and glutamine offer little benefit unless dietary intake is insufficient.
• The Anabolic Window Myth: Post-workout protein timing is less important than total daily intake

• Paul Warloski - Simple Endurance Coaching
• Marjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.