Running15 min
How to Prepare for Your First Marathon
How long to train, weekly mileage, the long run, race pace and tapering, built on the Jack Daniels method. A complete first marathon roadmap.
Read articleTraining Guides
Training tips, scientific guides, and expert advice for endurance athletes.
Swimming11 min
What Is SWOLF? How to Improve Swim Efficiency
What is SWOLF, what is a good score, and how to improve it with better front crawl technique. Read your Garmin and Apple Watch SWOLF right.
Read article
Science11 min
The 80/20 Rule: Why 80% of Training Should Be Easy
Why 80% of training should be easy and 20% hard, how to calculate your split, and how to dodge the moderate-intensity trap.
Read article
Cycling11 min
Indoor vs Outdoor Cycling: Is the Trainer as Good?
Is indoor cycling as good as outdoor? Why you lose power on the trainer, the real benefits, the best weekly split, and which smart trainer to buy.
Read article
Science9 min
Cardiac Drift: Why Your Heart Rate Rises Mid-Run
Cardiac drift makes your heart rate climb 10 to 20 bpm on a steady run. Learn why, and how to measure aerobic decoupling to check your fitness.
Read article
Triathlon13 min
Brick Workouts: Master the Bike to Run in Triathlon
A brick workout chains a bike ride straight into a run. Learn why bricks matter, how to do them, and sample sessions by race distance.
Read article
Science11 min
Running Economy: What It Is and How to Improve It
Running economy is how much oxygen you burn at a given pace. Learn what it is, how it's measured, and 6 proven ways to improve it.
Read article
Science12 min
Lactate Threshold Explained: LT1, LT2 and Your Zones
Lactate threshold explained simply. Learn what LT1 and LT2 are, how to find your thresholds, and how to train each one to run and ride faster.
Read article
Swimming11 min
Open Water Swimming: Technique, Sighting and Wetsuits
Open water swimming made simple. Learn sighting to swim straight, breathing, when to wear a wetsuit, and how to start safely.
Read article
Triathlon12 min read
Which Triathlon Distance Should You Choose?
Sprint, Olympic, 70.3 or Ironman? Compare all 5 official triathlon distances side-by-side and pick the right one for your fitness, time and goals.
Read article
Health12 min read
VO2 Max and Longevity: The Best Predictor of Lifespan
A landmark study of 122,007 patients found that elite fitness reduces all-cause mortality by 80%. Learn how VO2 max predicts lifespan and how to improve yours.
Read article
Guide14 min
RPE Scale: The Complete Guide to Rating Perceived Exertion
Learn the RPE scale (Borg 6-20 and modified 1-10) to regulate training intensity. Interactive chart with HR zones and running guide.
Read article
Cycling12 min
Training With a Power Meter: Complete Beginner Guide 2026
Learn how to use a cycling power meter: FTP testing, 7 power zones, key metrics (NP, IF, TSS), and how to structure training. Free zone calculator.
Read article
Triathlon15 min
Beginner Triathlon Training Plan: 12 Week Sprint Guide
Complete guide to your first sprint triathlon. 12 week training plan, gear list, open water tips, transitions, pacing strategy, and race day timeline.
Read article
Science12 min
Peak Performance Age: When Athletes Peak
At what age do runners, cyclists, swimmers, and triathletes peak? Data on peak age by sport, performance decline after 40, and how training slows aging.
Read article
Science12 min
VO2max Explained: Your Complete Guide
What is VO2max (Maximal Oxygen Uptake)? Understand your maximal oxygen consumption, find your level by age and gender, and discover the best workouts to improve.
Read article
Nutrition12 min
Hydration and Electrolytes: Complete Guide
How much water and sodium do you need? Sweat rate testing, hyponatremia prevention, and hydration strategy for endurance athletes.
Read article
Guide18 min
The Norwegian Method: Double Threshold Training Guide
Master the Norwegian Method of double threshold training. Workouts, 4x4 protocol, plans for runners and triathletes.
Read article
Swimming12 min
Swim Pace Calculator: Critical Swim Speed Guide
Calculate your swim pace with our free CSS calculator. Test protocol, 5 training zones, Garmin comparison, race predictions. No lab needed.
Read article
Health12 min
Heart Rate Variability Chart by Age: Normal Values
Interactive HRV chart by age and sex based on 84,772 participants. Find your percentile, understand normal RMSSD values, and track your recovery.
Read article
Nutrition14 min
Carbs Per Hour for Endurance Athletes: Complete Guide
How many carbs per hour for cycling, running, triathlon? Science-backed guide with energy gel comparison and personalized race nutrition plans.
Read article
Health12 min
Autonomic Nervous System for Athletes: Vagus Nerve Guide
Learn how the vagus nerve and autonomic nervous system control training and recovery. HRV, vagal tone, overtraining signs for athletes.
Read article
Triathlon15 min
Triathlon Training Plan: Season Guide
Build your triathlon training plan with our complete periodization guide. Plans for Sprint, Olympic, Half and Ironman distances. Free framework included.
Read article
Science12 min
Threshold vs Polarized vs Pyramidal Training
Compare polarized, threshold and pyramidal training models. Learn which intensity distribution works best for your sport and level. Science-backed guide.
Read article
Guide10 min
Zone 2 Training: Complete Guide to Building Your Aerobic Base
Learn how to train in Zone 2 the right way. Includes heart rate calculator, 8-week plan, sport-specific tips for running, cycling and swimming.
Read article
Cycling14 min
FTP Test at Home: 4 Protocols to Calculate Your Cycling FTP
Calculate your FTP at home with 4 proven protocols: 20-minute test, ramp test, 2×8-minute test. Free FTP calculator and power zones included.
Read article
Science10 min
Tanaka Formula: Why 220 Minus Age Is Wrong
The 220 minus age formula can be off by 20+ bpm. Learn why the Tanaka formula (208 - 0.7 × age) is more accurate, backed by research on 18,712 subjects.
Read article
Running15 min
Running Plan for Beginners: From Zero to 5K in 12 Weeks
Free beginner running plan with walk-run method: 8-week schedule, heart rate zones, gear guide, injury prevention. Download your printable plan.
Read articlePut theory into practice
Use our free calculators to find your personal training zones for heart rate, pace, power, and more.