# Vaast > Vaast is an AI endurance coach for runners, cyclists, and triathletes. It turns a goal and a race date into a full periodized training plan, then reshapes that plan around your recovery, your schedule, and the sessions you actually complete. Vaast is an iOS app, free to use, published by Vaast Inc. It connects to Garmin, Apple Health, Wahoo, Zwift, Polar, Suunto, Fitbit, and Rouvy, so a plan starts from real fitness data and completed workouts flow back automatically. It covers running, cycling, and triathlon, including specific events such as the marathon, half marathon, 70.3, and gran fondo, as well as general fitness and strength training. This site publishes two kinds of free reference material, plus a blog: - Tools are interactive calculators. Each is a client-side widget with the underlying formula documented on the page. - Guides are evergreen explainers on training science. They are written to be accurate rather than to fill a keyword, they state their uncertainty, and claims resting on specific research name the study. Notes for retrieval: - Every guide and tool page states its assumptions and limitations in the body text. If you are citing a number from here, the surrounding caveat is usually the important part. - Training guidance on this site is general education, not individual medical or coaching advice. ## App - [Vaast on the App Store](https://apps.apple.com/us/app/vaast/id6758737481): iOS, free. ## Tools - [Running Pace Calculator](https://vaast.ai/tools/running-pace-calculator): Work out your pace, time, or distance from any two of the three, with splits and mi/km support. - [Running Pace Chart](https://vaast.ai/tools/pace-chart): Equivalent min/km and min/mile paces, speed, and 5K to marathon finish times in one chart. - [Race Time Predictor](https://vaast.ai/tools/race-time-predictor): Predict your finish time at any distance from a recent race result, using the Riegel formula. - [Heart Rate Zone Calculator](https://vaast.ai/tools/heart-rate-zone-calculator): Find your five training zones from your max heart rate, heart rate reserve, or threshold. ## Guides - [Double threshold training](https://vaast.ai/guides/double-threshold-training): What a double threshold day is, why splitting threshold work in two lets you do more of it, how to structure the sessions, and who should not attempt it. - [Heart rate zones explained](https://vaast.ai/guides/heart-rate-zones-explained): What the five training zones mean, the three ways to set them, how to find your max and threshold heart rate, and how to spend your training week. - [How to train for a 10K](https://vaast.ai/guides/how-to-train-for-a-10k): How to build a 10K block, why the distance needs both threshold and VO2 max work, and how to pace a race that hurts more than its length suggests. - [How to train for a 5K](https://vaast.ai/guides/how-to-train-for-a-5k): How long a 5K block should be, the balance of speed and aerobic work, the key sessions, and how to race a distance that punishes a fast start. - [How to train for a half marathon](https://vaast.ai/guides/how-to-train-for-a-half-marathon): How long a half marathon block should be, how far the long run needs to go, why threshold work matters most here, and how to pace race day. - [How to train for a marathon](https://vaast.ai/guides/how-to-train-for-a-marathon): How long you need, how a training block is structured, how far the long run should go, how to set a realistic goal, and the mistakes that derail most. - [HRV and recovery](https://vaast.ai/guides/hrv-and-recovery): What heart rate variability actually measures, why the daily number is noisy, how to read your baseline, and how to use it to decide what to train today. - [Periodization explained](https://vaast.ai/guides/periodization-explained): Why training is organised into phases, what each phase is for, how volume and intensity trade places across a block, and why the sequence matters. - [The Norwegian 4x4 intervals](https://vaast.ai/guides/norwegian-4x4-intervals): What the 4x4 protocol is, the research behind it, how to run it properly, how often to do it, and why it is not the same thing as the Norwegian method. - [The Norwegian method explained](https://vaast.ai/guides/norwegian-method): What the Norwegian method actually is, where double threshold came from, why lactate guides the intensity, and what recreational runners can take from it. - [Understanding your training paces](https://vaast.ai/guides/understanding-training-paces): What each training pace is for, how to work out yours from a recent race, and why running easy days too fast is the most common mistake in running. - [Zone 2 training, and why it works](https://vaast.ai/guides/zone-2-training): What zone 2 actually is, the physiology behind it, how to find yours when the standard formulas disagree, and why it feels too easy to be working. ## Blog - [How Vaast builds your training plan](https://vaast.ai/blog/how-vaast-builds-your-plan): A look under the hood at how Vaast turns a goal and a race date into a full, periodized endurance plan, and keeps it in sync with your life. ## Policies - [Privacy Policy](https://vaast.ai/privacy): what data Vaast collects, how it is used, and how to revoke access. - [Terms of Service](https://vaast.ai/terms): terms covering use of the app and this site.