The Athlete's Compass

In this episode of The Athletes Compass, Paul Warloski, Dr. Paul Laursen, and Marjaana Rakai explain Athletica’s Workout Reserve and the new Systems Engagement feature. Workout Reserve is described as a battery-like metric that shows how close an athlete is to their historical best across different durations, from short sprint efforts to long aerobic performances. The team discusses how athletes can use it in real time through Velocity or Garmin, how negative values can signal breakthrough efforts, and why good historical data is essential. They also explain how Systems Engagement helps athletes and coaches see which physiological systems were stressed in a workout or race, making it easier to reverse engineer training toward the actual demands of an event.Key episode takeawaysWorkout Reserve acts like a “battery” showing how much capacity an athlete has left relative to their recent historical bests.A value near 100% suggests the athlete is fresh relative to that effort, while 0% means they are approaching a known personal limit. Negative values indicate new, uncharted territory.Workout Reserve can be viewed retrospectively in Athletica, live in Velocity sessions, or through the Garmin Workout Reserve data field.Systems Engagement shows which energy systems were stressed during a workout or selected segment, such as neuromuscular sprint, anaerobic, VO2 max, threshold, or aerobic systems.A 30/30 interval session may engage both VO2 max and threshold systems, which matches the expected training adaptations.The tool is most useful when athletes have enough valid historical data, including power or pace tests such as FTP tests, 5K tests, or sport-specific calibration sessions.Workout Reserve and Systems Engagement are based on external load, such as pace or power, not internal load measures like heart rate, lactate, or RPE.Coaches can use Systems Engagement to check whether an athlete actually trained the intended system.Race analysis can help athletes identify which physiological systems were most taxed, then design training to target those demands.Not every session should push Workout Reserve to zero or negative; easy aerobic sessions still have a purpose.How a ProTour cycling coach uses Athletica Workout ReserveWorkout Reserve: A New Way to Understand Performance with Dr. Andrea ZignoliScientific Paper in Sports EngineeringRace Analysis - Volta ValencianaGarmin Connect IQ | HomeTrain and Race with WR on GarminAthletica Workout Reserve | HomePaul Warloski - Simple Endurance CoachingMarjaana Rakai | Nordic Performance Lab

In this episode of The Athletes Compass, Dr. Paul Laursen and the team break down the science and practical application of the second threshold — also known as LT2, VT2, FTP, or critical power. They explain what physiologically happens when you cross this boundary, why base training is essential before adding threshold work, and how over-unders, tempo sessions, and VO2 max intervals raise performance. The conversation explores common mistakes athletes make (especially doing too much intensity), the role of durability, and how to assess threshold progress without lab testing. If you want to train smarter, improve pacing, and sustainably increase performance, this episode delivers a masterclass in intensity control.Key TakeawaysLT1 vs LT2: LT1 (aerobic threshold) = top of Zone 2, sustainable “all-day” effort. LT2 (second threshold) = highest sustainable steady-state effort before rapid fatigue.Above LT2: Glycolytic demand increases, lactate accumulates faster, heart rate drifts, and fatigue accelerates.Functional vs Lab Testing: FTP and critical power are practical field markers of LT2. Lab tests measure physiology, but field tests often matter more for performance.Day-to-Day Variation Is Real: Sleep, fueling, equipment, environment, and training phase can significantly affect test results.Base Training First: A strong aerobic base (mitochondrial development) improves tolerance to threshold work and increases fat oxidation capacity.Over-Unders Work Because: They stimulate mitochondrial adaptations by forcing lactate clearance and improving aerobic durability.Intensity Control Matters: Spending more time in the correct zone is more beneficial than constantly pushing the top end.Most Common Mistake: Too much high-intensity work without sufficient aerobic base.Durability Is the Goal: Threshold training should build resilience so performance doesn’t break down late in races.Paul Warloski - Simple Endurance CoachingMarjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.

In this episode of Athlete’s Compass, hosts Paul Warloski, Dr. Paul Laursen, and Marjaana Rakai explore the overlooked yet critical elements of pre-race preparation: warmups and openers. Drawing on science and experience, they break down concepts like post-activation potentiation (PAP), the Q10 temperature effect, VO2 kinetics, and how proper timing, intensity, and individual context can make or break race performance. The trio shares personal anecdotes, training data insights, and cautionary tales (including cold-water swims gone wrong), helping athletes navigate both physiological and psychological readiness strategies. Whether you’re a crit racer, triathlete, or weekend warrior, this episode will change the way you approach race day — and the day before.Key TakeawaysPost-Activation Potentiation (PAP) boosts nervous system readiness for explosive performance.Q10 effect (temperature-driven) enhances muscle enzyme activity—warm muscles perform better.VO2 kinetics are improved with short, intense primers done 5–10 minutes before start time.Day-before openers should include high-intensity, low-volume efforts to keep CNS sharp without fatigue.Warmup routines are highly individual—test in training, adjust for temperature and race type.Over-warming or overtraining pre-race is a common mistake; less is more.Cold environments demand longer warmups and appropriate clothing to avoid CNS suppression.Caffeine can enhance CNS drive when timed 30–90 minutes before competition—test before race day.Paul Warloski - Simple Endurance CoachingEffect Of High Intensity Intervals 24hr Prior To A Simulated 40 KM Time TrialThe Effects of a Cycling Warm-up Including High-Intensity Heavy-Resistance Conditioning Contractions on Subsequent 4-km Time Trial Performance - PubMedEffect of warm-up on cycle time trial performance - PubMedImprovement of Oxygen-Uptake Kinetics and Cycling Performance With Combined Prior Exercise and Fast Start - PubMedMarjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.

In this episode, the Athletes Compass team dives into the physiology and performance science behind 30/30 HIIT intervals—30 seconds on, 30 seconds off. Dr. Paul Laursen explains why these short, intense bursts are so effective at improving VO2 max and recruiting fast-twitch muscle fibers. With insights into training stress, recovery, athlete profiling, and when to use short versus long intervals, the conversation highlights how even endurance athletes can benefit from raising their "ceiling" with strategically timed HIIT sessions. They also cover programming for different athlete types and how tools like Athletica and Velocity help customize training to individual needs.Key Takeaways:30/30 intervals (30 seconds on, 30 seconds off) effectively recruit fast-twitch fibers and promote adaptations in both the cardiovascular and muscular systems.These short intervals stimulate VO2 max while minimizing long-term fatigue compared to longer intervals.Power output is higher during 30/30s than in 4x5 minute VO2 workouts, leading to better adaptations in well-trained athletes.Recovery periods between intervals are key—passive recovery enables myoglobin resaturation and better performance.30/30s can benefit even Ironman athletes, despite the lack of specificity to long race paces.Athlete type matters: “Diesel” athletes may prefer longer intervals; “twitchy” athletes often thrive with short ones.Tools like Athletica’s workout reserve and power profile analysis help guide interval prescription.Heart rate and power trends during sets can indicate whether an athlete is adapting well—or overreaching.Paul Warloski - Simple Endurance CoachingAthlete Profiling PrimerThe Power of Optimizing HIIT Short IntervalsMarjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.

In this episode of The Athlete’s Compass, the team introduces Athletica’s newly launched AI coach—an intelligent training assistant that combines large language models (LLMs) with athlete-specific data like HRV, sleep, and training load. Unlike generic AI tools, this coach taps into the HIIT Science textbook and contextualizes advice based on six weeks of an athlete’s training history. Paul Laursen, Marjaana Rakai, and Paul Warloski walk through how it works, what sets it apart, and demonstrate its capabilities in real-time. The conversation highlights not only the tech’s sophistication but its potential to empower athletes and coaches alike through contextual, science-backed decision-making.Key TakeawaysAI + Personal Data = Precision Coaching: The AI coach analyzes training data like HRV, heart rate, and sleep to give context-aware, real-time advice.HIIT Science Textbook is Embedded: It doesn’t guess—its responses are backed by content from The Science and Application of High-Intensity Interval Training.Real-Time Scenarios: Whether you're sick, tapering, or targeting a hilly Ironman, the AI provides personalized strategies.Built-In Guardrails: It won’t override your training plan but will suggest appropriate tweaks based on your context.For Coaches Too: While not yet multi-athlete enabled, future updates will allow coaches to use it across their roster.Customization: Users can adjust the coach’s personality (casual/professional) and depth (plain language to sports science level).AI Agent Architecture: It uses Retrieval-Augmented Generation and purpose-built agents (e.g., for recovery or training load optimization).More Than a Chatbot: Unlike ChatGPT, this coach knows your actual training history and adjusts accordingly.Paul Warloski - Simple Endurance CoachingMarjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.