HealthStars: Train Your Heart

Track every interval from your wrist — live heart rate, zones and recovery. Then take your one weekly shot at the Max Heart Rate Challenge and climb the board.

Most training apps tell you how the workout went. HealthStars tells you what today's workout should be — and whether your body can actually take it.

Set one goal, log one session, and the plan builds itself out of your own numbers: your VO₂ category, body composition, current training level and history. A conditioned runner skips the base weeks. A sedentary one doesn't get handed sprints in week one.

READINESS — A SCORE BEFORE THE SESSION, NOT A VERDICT AFTER IT Every planned workout is scored from 0 to 100 against what your body actually brought to it: last night's sleep, stress, nutrition, hydration, medication adherence, the session's own intensity, and the temperature, humidity and altitude you'll be training in. You get one number — plus the exact factors holding it down, ranked by how much drag each one is adding. Sleep the biggest problem today? Move the sprint block, or run it at reduced intensity.

THE PROGRESSION — ZONES IN ORDER, PRESCRIBED IN WEEKS • MICT (Zone 2–3). Moderate continuous work that builds the aerobic base your intervals will spend. • HIIT (Zone 4). Hard efforts with measured recovery, timed against your own heart-rate numbers. • SIT (Zone 5). All-out sprint intervals — the sharp end of the plan. It opens only once your conditioning, and the day's readiness, support it.

YOUR SIT RATIO Peak effort and recovery, combined into one number. Lower is better. Hold your heart rate near your max long enough and the app scores how fast you come back down, then shows the lifestyle factors that slowed it. Zones run from blue (elite recovery) through green, orange and red, so a session reads at a glance.

TRAIN TOWARD A REAL TARGET • Fitness — move your VO₂ max, tracked session to session. • Blood pressure — train toward a systolic target you set with your clinician. • HbA1c — interval work aimed at a glycemic target you set once. • Weight — a rate of change, and the projected date it gets you there. Your goal ETA comes from your actual rate of progress, and it moves when your rate moves.

BUILT FOR APPLE WATCH Start the session on iPhone, then run it from your wrist: live heart rate, interval and rest cues, and zone targets as you reach them. Completed workouts are written back to Apple Health.

CLUBS, LEADERBOARDS AND THE CHALLENGE Join or create a club, take a coaching role, and watch the standings move on daily, weekly and season leaderboards. The Max Heart Rate Challenge scores the time you hold above 95% of your max heart rate: one official attempt per window, men's and women's divisions scored separately, a warm-up compliance check on every attempt, and tie breakers on quality — lower SIT ratio first, then greater distance in your top zone. Invite a training partner and it's tracked to your account.

WHAT YOU'LL NEED • An iPhone, plus an Apple Watch for live heart rate and session control. • Permission to read heart-rate and workout data from Apple Health. • Ages 13 and up.

HealthStars is a fitness and training app, not a medical device. It does not diagnose, treat, cure or prevent any disease. Talk to your clinician before beginning high-intensity training, and before training toward a blood pressure, HbA1c or weight target.