Half Ironman Training Plan: A 16-Week 70.3 Plan With Fueling for Every Phase
A free 16-week 70.3 training plan for athletes who can swim 1,000 m, run 10 km, and ride for two hours. Base, build, peak, and taper phases, weekly hours and key sessions for every week, heart rate zones, a sample week, how to scale it to 6 or 10 hours, and what to eat on each kind of training day.
Quick answer
A 16-week 70.3 training plan has four phases: base (weeks 1 to 4) for easy aerobic volume and swim technique, build (weeks 5 to 12) for race-effort intervals and a weekly brick, peak (weeks 13 to 14) for race rehearsals, and taper (weeks 15 to 16) where volume drops by about 40 then 60 percent. Training grows from about 6 to 10.5 hours a week, with 2 to 3 swims, 3 rides, and 3 runs, a longest ride of about 3.5 hours and a longest run of about 1 hour 40 minutes. Keep about 80 percent of training easy. Eat 3 to 5 g of carbs per kg on light days, 5 to 7 g on moderate days, and 6 to 10 g on long ride and brick days, and build long-ride fueling to 60 to 90 g of carbs per hour before race day.
A half ironman, or 70.3, is a 1.9 km (1.2 mi) swim, a 90 km (56 mi) bike, and a 21.1 km (13.1 mi) run. This 16-week 70.3 training plan takes you from about 6 to 10.5 hours of training a week in four phases: base, build, peak, and taper. Each week has two to three swims, three rides, and three runs, with a long ride, a long run, and, from week 5, a weekly brick. Most age-group athletes finish in 5 to 7 hours, and the usual cut-off is 8 hours 30 minutes.
Below are the hours and key sessions for every week, plus the part most plans leave out: what to eat. A 70.3 week can hold a 45 minute swim and a 4 hour brick, and your food needs to change with it. The long rides are also where you train your gut to take the 60 to 90 g of carbs per hour the race will ask for.
The Plan at a Glance
| Phase | Weeks | Hours per week | Focus |
|---|---|---|---|
| Base | 1 to 4 | 6 to 7 (5 in week 4) | Easy aerobic volume, swim technique, strides, habit |
| Build | 5 to 12 | 7.5 to 10 (6 and 7 in recovery weeks 8 and 12) | Threshold intervals, race-effort blocks, a weekly brick, gut training |
| Peak | 13 to 14 | 10 to 10.5 | Longest ride and run, open water, full race rehearsal |
| Taper | 15 to 16 | About 6.5, then about 4 plus the race | Volume down 40 to 60 percent, short race-pace efforts stay |
Who This Plan Is For
- You can swim 1,000 m (about 0.6 mi) without stopping, in any stroke.
- You can run 10 km (6.2 mi) without walking, at any pace.
- You can ride for two hours on a road or triathlon bike.
- You can train six days a week for about 6 hours, rising to about 10 hours in the peak weeks.
- You have a pool, a bike, and ideally a heart rate monitor. A power meter helps but is not needed.
If you are not there yet, spend 4 to 8 weeks building to those numbers first, or start with an Olympic distance race (linked at the end). If you have a heart condition, high blood pressure, or you are new to exercise, see a doctor before you start.
How Hard to Go: Heart Rate Zones and Effort
Most of this plan is easy. Successful endurance athletes do about 80 percent of sessions at low intensity and about 20 percent hard. In a 9-week trial with 48 well-trained runners, cyclists, and triathletes, a polarized mix of mostly easy work plus a little very hard work raised aerobic capacity by about 12 percent, more than threshold-heavy or high-volume training. Keep easy days easy, so the hard days can be hard.
| Zone | Heart rate (% of max) | Effort (RPE 1 to 10) | How it feels and what it is for |
|---|---|---|---|
| Zone 1: Recovery | 50 to 65% | 1 to 2 | Very easy. Warm-ups, cool-downs, recovery spins. |
| Zone 2: Endurance | 65 to 78% | 3 to 4 | You can talk in full sentences. Most of your training. |
| Zone 3: Tempo | 78 to 85% | 5 to 6 | Short sentences only. This is roughly 70.3 race effort. |
| Zone 4: Threshold | 85 to 92% | 7 to 8 | A few words at a time. Intervals of 8 to 20 minutes. |
| Zone 5: VO2 max | 92 to 100% | 9 to 10 | No talking. Short intervals, used sparingly. |
Take your max heart rate from a recent hard race or field test, not from 220 minus your age. Bike heart rate usually sits 5 to 10 beats lower than run heart rate at the same effort. With a power meter, set bike zones from a 20 minute test. In the pool, go by effort and pace per 100 m. On race day, the bike should feel like RPE 5 to 6.
The 16-Week 70.3 Training Plan, Week by Week
| Week | Phase | Hours | Long ride | Long run | Key sessions |
|---|---|---|---|---|---|
| Week 1 | Base | 6 | 1:45 Zone 2 | 50 min | Swim drills plus 6 x 100 m; strides after two runs |
| Week 2 | Base | 6.5 | 2:00 Zone 2 | 55 min | Swim 8 x 100 m steady; bike 4 x 5 min Zone 3 |
| Week 3 | Base | 7 | 2:15 Zone 2 | 60 min | Swim 1,200 m continuous; bike 3 x 8 min Zone 3; run 20 min Zone 3 |
| Week 4 | Recovery | 5 | 1:30 Zone 2 | 45 min | Tests: 400 m swim time trial, 20 min bike test, 5 km run |
| Week 5 | Build | 7.5 | 2:15 plus 15 min run | 65 min | Swim 6 x 200 m hard; bike 3 x 10 min Zone 4 |
| Week 6 | Build | 8 | 2:30 plus 15 min run | 70 min | Run 3 x 8 min Zone 4; bike 2 x 20 min Zone 3 |
| Week 7 | Build | 8.5 | 2:45 plus 20 min run | 75 min | Swim 5 x 300 m at race pace; bike 3 x 12 min Zone 4 |
| Week 8 | Recovery | 6 | 2:00 Zone 2 | 55 min | Repeat the week 4 tests; first open water swim if you can |
| Week 9 | Build | 9 | 3:00 plus 20 min run | 80 min | Bike 3 x 15 min race effort; run 2 x 15 min Zone 3 |
| Week 10 | Build | 9.5 | 3:00 plus 30 min run | 85 min | Swim 1,900 m continuous; bike 2 x 20 min Zone 4 |
| Week 11 | Build | 10 | 3:15 plus 30 min run | 90 min | Long run with the last 20 min at race effort; swim 4 x 400 m |
| Week 12 | Recovery | 7 | 2:15 Zone 2 | 60 min | Easy week; test your race kit |
| Week 13 | Peak | 10 | 3:30 with 2 x 30 min race effort, plus 30 min run | 1:40 | Open water 2,000 m; run 3 x 10 min Zone 3 to 4 |
| Week 14 | Peak | 10.5 | 3:00 race rehearsal plus 45 min run | 75 min | Full race-day fueling on the brick, same breakfast and products |
| Week 15 | Taper | 6.5 | 2:00 with 3 x 10 min race effort, plus 15 min run | 60 min | Short race-pace efforts in all three sports |
| Week 16 | Race week | About 4 plus the race | 60 min with 3 x 3 min race effort | 30 min with strides | Short swim, ride, and run the day before; race |
The plan runs three weeks up and one week down, so your body absorbs the work. A normal week has 8 to 9 sessions: 2 to 3 swims of 2,000 to 3,000 m, 3 rides, and 3 runs, one of them off the bike. Add one or two short strength sessions of 20 to 30 minutes. You never run the full 21.1 km in training. A 1 hour 40 minute long run plus weekly bricks is enough and keeps injury risk down.
Key Sessions in Each Phase
| Phase | Swim | Bike | Run | Brick |
|---|---|---|---|---|
| Base (weeks 1 to 4) | Drills, 6 to 10 x 100 m, build to 1,200 m continuous | Zone 2 long ride, short Zone 3 blocks | Zone 2 runs with 4 to 6 x 20 s strides | Optional 10 min jog after a ride |
| Build (weeks 5 to 12) | 6 to 8 x 200 m or 4 x 400 m, hard and steady | 3 x 10 to 2 x 20 min in Zone 4; race-effort blocks on the long ride | 3 x 8 to 3 x 10 min in Zone 4; long run to 90 min | Weekly: long ride, then 15 to 30 min run |
| Peak (weeks 13 to 14) | Open water 2,000 m continuous, sighting every 6 to 8 strokes | 2 x 30 to 60 min at race effort in race position | Long run to 1:40, last 20 min at race effort | 3 to 3.5 h ride plus 30 to 45 min run, full race fueling |
| Taper (weeks 15 to 16) | Shorter swims, 4 to 6 x 100 m at race pace | Shorter rides, 3 x 10 min at race effort | Short runs, strides, 2 x 5 min at race effort | One short brick about 10 days out |
A Sample Build Week (Week 10, 9.5 Hours)
| Day | Session | Time |
|---|---|---|
| Monday | Swim 2,200 m with 6 x 200 m hard, 30 s rest | 0:45 |
| Tuesday | Bike: 2 x 20 min in Zone 4, 5 min easy between | 1:15 |
| Wednesday | Run: 3 x 10 min in Zone 3 to 4 with 3 min jog, easy warm-up and cool-down | 0:55 |
| Thursday | Swim 1,900 m continuous, then an easy Zone 2 ride | 1:45 |
| Friday | Rest, or 20 min easy swim or mobility | 0:00 to 0:20 |
| Saturday | Brick: 3:00 Zone 2 ride with 3 x 15 min at race effort, then 30 min run | 3:30 |
| Sunday | Long run: 85 min in Zone 2 | 1:25 |
Tuesday and Wednesday are the quality days, Saturday is the big day, and the rest is easy. Move the swims to fit your pool, but do not put the long run the day before the brick.
How to Scale the Plan: 6 Hours vs 10 Hours a Week
| What changes | 6 hours a week (time-crunched) | 10 hours a week (the full plan) |
|---|---|---|
| Hours | About 60 to 65 percent of each week: 4 in base, 6 to 7 at peak | As written: 6 in week 1, 10.5 at peak |
| Swims | 2 a week, 2,000 to 2,500 m each | 3 a week, 2,000 to 3,000 m each |
| Rides | 2: one interval ride and the long ride, capped at 2:30 to 3:00 | 3: intervals, easy, and a long ride up to 3:30 |
| Runs | 2 plus the brick run; long run capped at 75 to 90 min | 3 plus the brick run; long run up to 1:40 |
| Keep no matter what | Long ride, brick, one quality session per sport | Same, plus the third swim |
| Cut first | Easy midweek sessions and strength | Easy sessions, never the long ride or brick |
Six hours a week gets most people to a strong finish. Ten hours lets you race it. If you miss a few days, do not stack the missed work into the next week. If you miss a full week through illness, repeat the week before it.
The Fueling Layer: Why Your Food Changes Every Day
A week that runs from a 45 minute swim to a 3.5 hour brick cannot be fueled by the same menu every day. Eat for the average day and you under-fuel the long ride and brick, the sessions that matter most, and over-fuel the rest days. Carbohydrate should move the most. Protein stays fairly steady.
Daily Carbs by Training Load
| Training day | Carbs per kg per day | 60 kg (132 lb) athlete | 75 kg (165 lb) athlete |
|---|---|---|---|
| Rest day, technique swim, or under 1 hour easy | 3 to 5 g | 180 to 300 g | 225 to 375 g |
| About 1 hour of moderate training (most weekdays) | 5 to 7 g | 300 to 420 g | 375 to 525 g |
| 1 to 3 hours with intervals, or long ride and brick days | 6 to 10 g | 360 to 600 g | 450 to 750 g |
These ranges come from the sports nutrition position stand of the American College of Sports Medicine and its dietitian partners. Use the low end for easy volume and the high end when the day has intervals or two sessions. Protein should be 1.2 to 2.0 g per kg per day, spread over four or five meals of about 0.3 g per kg, or 20 to 25 g for most athletes. Fat fills the rest, but keep it above about 20 percent of your calories.
What to Eat Around Each Session
| Session | Before | During | After |
|---|---|---|---|
| Under 60 minutes (most swims, easy runs, short intervals) | A normal meal 2 to 4 hours before, or a small snack | Water. You do not need carbs. | Your next normal meal, with about 0.3 g protein per kg |
| 60 to 150 minutes (interval rides, long runs, mid-length rides) | 1 to 2 g carbs per kg, 2 to 3 hours before | 30 to 60 g carbs per hour, fluid to thirst | A meal within 1 to 2 hours with carbs and 0.3 g protein per kg |
| Long rides and bricks over 2.5 hours | 1.5 to 3 g carbs per kg, 2 to 4 hours before | 60 to 90 g carbs per hour from glucose and fructose, 400 to 800 ml fluid and 300 to 600 mg sodium per hour | 1 to 1.2 g carbs per kg per hour for up to 4 hours if you train again the same day, plus 0.3 g protein per kg |
On bricks, take your last gel about 10 minutes before you get off the bike. On runs of 30 minutes or more off the bike, keep taking 30 to 60 g per hour. Heavy or salty sweaters need the top of the sodium range, and a sweat test tells you where you sit.
Train Your Gut on the Long Rides
Your race asks for 60 to 90 g of carbs per hour on the bike. Few people manage that without practice, and stomach problems are one of the most common reasons a long triathlon goes wrong. The good news: the gut adapts. Regular practice speeds up stomach emptying, reduces fullness, and raises the number of carb transporters in your gut. In one study, 16 trained cyclists and triathletes who ate more carbohydrate for 28 days, including during training, burned more of the glucose they drank during a 100 minute ride: about 64 g instead of 55 g.
| Weeks | Carbs per hour on long rides and bricks | How to do it |
|---|---|---|
| 1 to 4 | 30 to 45 g | One bottle of sports drink plus half a bar or a gel each hour. Note how your stomach feels. |
| 5 to 8 | 45 to 60 g | Add a second source. Start using products that mix glucose and fructose. |
| 9 to 12 | 60 to 75 g | Switch to the gels and drink mix you will race with. Take something every 15 to 20 minutes. |
| 13 to 14 | 70 to 90 g, your race target | Full rehearsal on the brick: same breakfast, same timing, same products. Practice 30 to 60 g per hour on the run. |
| 15 to 16 | Race target on shorter rides | Nothing new. Keep the stomach used to it. |
- Rate your stomach from 0 to 10 after each long session. Above 3, drop back one step for a week.
- Above 60 g per hour, mix glucose and fructose. Glucose alone is absorbed at about 60 g per hour.
- Practice at race effort and, if your race is hot, in the heat. Both make the gut less tolerant.
Race Week and Race Day in Short
| When | Target | Note |
|---|---|---|
| Taper weeks 15 and 16 | 5 to 7 g carbs per kg on most days | Training drops, but do not diet. You are storing fuel. |
| Last two days | 8 to 10 g carbs per kg per day | Lower fiber and fat, carb drinks help |
| Breakfast, 2 to 4 hours before | 1 to 3 g carbs per kg | The breakfast you rehearsed in week 14 |
| Bike | 60 to 90 g carbs per hour | Most of the day's fueling happens here |
| Run | 30 to 60 g carbs per hour | Smaller doses, more often, water at aid stations |
The full race-day plan, with bottle counts, sodium by sweat rate, and what to do when nausea starts, is in our 70.3 nutrition plan, linked at the end.
Tracking this by hand is a lot of work. Mavr does it from your synced training: a different carb target for a swim day and a brick day, and a fuel plan for each long session.
This plan changes what you should eat every day, from a 45 minute swim to a 3.5 hour brick. Mavr syncs your sessions from Garmin, TrainingPeaks, Strava, or Intervals.icu, sets carbs, protein, and fat for each day, and plans carbs, fluid, and sodium for every long ride and brick.
Frequently Asked Questions
How many hours a week do I need to train for a 70.3?
Most age-group athletes finish well on 6 to 10 hours a week, with the biggest weeks 3 to 4 weeks before the race. About 6 to 7 hours at peak is enough to finish strong. About 10 to 12 hours lets you race for a time.
Is 16 weeks enough to train for a half ironman?
Yes, if you start able to swim 1,000 m, run 10 km, and ride for two hours. If you cannot do those yet, add 4 to 8 weeks of easy base training before week 1.
How long should my longest ride and run be before a 70.3?
Build the long ride to 3 to 3.5 hours, which covers the 90 km for most people, and the long run to about 1 hour 40 minutes. You do not need to run 21.1 km in training. Weekly bricks teach you to run off the bike.
How often should I do brick workouts?
Once a week from week 5, usually after the long ride. Most bricks need only 15 to 45 minutes of running. The aim is to get used to running on tired legs and to practice fueling, not to add big run volume.
How many carbs should I eat a day when training for a 70.3?
About 3 to 5 g per kg of body weight on rest and light days, 5 to 7 g per kg on days with about an hour of moderate training, and 6 to 10 g per kg on long ride, brick, and interval days. For a 70 kg athlete that is roughly 210 to 350 g, 350 to 490 g, and 420 to 700 g.
How much should I eat on long rides in training?
Aim for 30 to 60 g of carbs per hour on rides of 1 to 2.5 hours and 60 to 90 g per hour on longer rides and bricks. Build up to the higher amounts over several weeks and use glucose plus fructose products above 60 g per hour.
Sources
Sources and official references
- 1.Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic PerformanceJournal of the Academy of Nutrition and Dietetics (Thomas et al., 2016) · Daily carbs of 3 to 5, 5 to 7, and 6 to 10 g/kg by training load; 30 to 60 g/h in 1 to 2.5 h sessions, up to 90 g/h beyond; protein 1.2 to 2.0 g/kg and 0.3 g/kg per meal
- 2.Nutrition for Endurance Sports: Marathon, Triathlon, and Road CyclingJournal of Sports Sciences (Jeukendrup, 2011) · Carbohydrate delivery matched to event duration and intensity; gut problems are common in long triathlons
- 3.Training the Gut for AthletesSports Medicine (Jeukendrup, 2017) · Gastric emptying, fullness, and intestinal carb absorption adapt to regular carbohydrate intake
- 4.Daily Training With High Carbohydrate Availability Increases Exogenous Carbohydrate Oxidation During Endurance CyclingJournal of Applied Physiology (Cox et al., 2010) · 28 days of high carbohydrate intake raised the use of ingested glucose during a 100 minute ride from 54.6 to 63.6 g
- 5.What Is Best Practice for Training Intensity and Duration Distribution in Endurance Athletes?International Journal of Sports Physiology and Performance (Seiler, 2010) · Successful endurance athletes do about 80 percent of sessions at low intensity and about 20 percent hard
- 6.Polarized Training Has Greater Impact on Key Endurance Variables Than Threshold, High Intensity, or High Volume TrainingFrontiers in Physiology (Stöggl and Sperlich, 2014) · 48 well-trained endurance athletes; polarized training raised VO2 peak by 11.7 percent over 9 weeks, more than the other models
- 7.Effects of Tapering on Performance: A Meta-AnalysisMedicine and Science in Sports and Exercise (Bosquet et al., 2007) · A 2-week taper cutting volume by 41 to 60 percent while keeping intensity and frequency gave the best results
Prompt ideas for AI assistants
- “Adapt this 16-week 70.3 plan to 7 hours a week with a swim squad on Tuesday and Thursday.”
- “How many carbs should I eat the day of a 3 hour brick at 72 kg?”
- “Build me a gut-training plan to reach 80 g of carbs per hour on the bike.”
Mavr reads your 70.3 plan from Garmin, TrainingPeaks, Strava, or Intervals.icu and sets carbs, protein, and fat for each training day, plus carbs, fluid, and sodium per hour for every long ride and brick.
Written by
Mavr Sports Nutrition Team
The Mavr sports-nutrition team translates peer-reviewed endurance research (Jeukendrup, Burke, the ISSN) into daily fueling for runners and triathletes.