Olympic vs 70.3 Triathlon: How the Training Block Differs

You just crossed the line at your first Olympic distance race, and the 70.3 is already living in your head. Everyone says it’s a step up, but nobody tells you what that actually means week to week. Is it just more of the same sessions, stretched longer? I’m going through that exact jump myself right now, and the honest answer is that Olympic vs 70.3 training doesn’t just add volume. It reshapes the whole week.

TL;DR

Olympic vs 70.3 training differs in three real ways: race intensity drops from close to threshold down to sustained tempo effort, swim volume goes up by more than the extra 400 metres would explain, and the long ride stops being just another hard session and becomes the one everything else in the week has to protect.

Key Takeaways

• Skipping Olympic and going straight to 70.3 is reasonable if you already have the aerobic base for it, but the actual race demands (a 3+ hour bike leg, a run pushing two hours) are bigger than the training floor to start the block.
• Weekly hours usually go up by 2 to 4, landing around 10 to 13 hours during a 70.3 build. Not a dramatic jump on paper.
• Target bike intensity drops from roughly 80-88% of FTP at Olympic distance to 72-82% at 70.3, so training shifts from threshold work toward sustained tempo.
• Swim volume increases by more than the extra 400 metres of race distance explains.
• Brick workouts get longer and more specific: a 3+ hour ride into a 1:30 run in peak weeks, not a short ride into a quick jog.
• Practicing race fuelling becomes a weekly habit, not a race-week afterthought.

Here’s the comparison at a glance before we get into the why:

Metric	Olympic	70.3
Swim	1.5 km	1.9 km
Bike	40 km	90 km
Run	10 km	21.1 km
Bike leg time	~1:10-1:20	2:30+ hrs
FTP target	80-88%	72-82%
Weekly hours*	~6-10	~10-13

*Build/peak phase, intermediate age-groupers.

How much extra training the jump actually takes

Most coaching guidance puts a 70.3 build somewhere around 10 to 13 hours a week for intermediate and advanced age-groupers, roughly 2 to 4 hours more than a typical Olympic build. On paper, that’s not dramatic.

What actually changes is the shape of the week, not just the total minutes in it. Olympic training tends to revolve around a couple of key intensity sessions, hard bike or run efforts, with aerobic work filling the gaps around them. In 70.3 training, the long ride becomes the anchor. Everything else has to protect it. Hammer a threshold run on Wednesday and you’ll feel it Saturday, and a compromised long ride on Saturday drags down Sunday’s long run behind it. The sequencing of stress across the week starts to matter as much as the total load.

Where the intensity actually goes: tempo replaces threshold

This is the part that surprised me most once I actually started training the block. Race pacing drops from roughly 80 to 88 percent of FTP at Olympic distance down to about 72 to 82 percent at 70.3 (full breakdown in The Right FTP Percentage for Every Triathlon Distance). That’s not a rounding difference. It changes what a hard session is supposed to feel like.

Training my own 70.3 block, the shift showed up fast. A lot more time sitting in tempo, noticeably less time gasping through threshold intervals. It’s a different kind of hard: less about surviving a short, sharp effort and more about holding a pace you could, in theory, argue with someone while doing.

None of this works if you’re pacing off a number you haven’t actually tested. If it’s been a while since you checked yours, here’s how to test your threshold properly before you try to hit any of these percentages.

Swim volume jumps by more than the distance explains

The 70.3 swim is 1.9 km against Olympic’s 1.5 km, about 27 percent longer. My own swim volume went up by more than that. Longer swim efforts reward aerobic economy over raw speed, and a fatigued swim start costs you more when you’ve still got a 90 km bike and a half marathon ahead of you instead of 40 km and 10 km. The extra pool time isn’t really about swimming faster. It’s about making the swim cost less of what you need for everything after it.

Brick workouts get longer, not just more frequent

Olympic-distance brick workouts tend to be short and sharp: a solid ride followed by a run off tired legs, mostly teaching your body to switch from spinning to running cadence. My 70.3 bricks in peak weeks look nothing like that. Think a 3-plus hour ride straight into a 1:45 run.

The point of the session changes too. It’s no longer just teaching your legs to run off the bike. It’s teaching your whole system, fuelling included, to hold form under real, accumulated fatigue. That’s a session you feel for two days, and it’s supposed to be.

Fuelling stops being optional

At Olympic distance, most athletes get away with pre-race fuelling and maybe a gel if the day’s hot. At 70.3, in-race fuelling is mandatory, and it has to be trained, not guessed at on race morning. That means practicing intake on the long rides and inside the bricks, the same way you’d practice pacing, and it ties directly into how much sodium you actually need during a race, which becomes a real variable once you’re out there for hours instead of minutes.

Get it wrong and it shows up one of two ways. Under-fuel and it’s a straightforward bonk: glycogen runs low, pace drops, and the run turns into survival mode somewhere in the second half. That’s a different failure than cramping, worth knowing the difference, covered in The Difference Between Bonking and Cramping.

The other failure mode is the one that catches people who think they’re being careful. Feel behind on calories around hour two, so you take down two gels back to back to catch up. Your gut has never processed that much carbohydrate at once in training, and it can’t keep up mid-race either. That shows up as bloating, nausea, or an unplanned bathroom stop, all of which cost more time than the calories you were chasing would have saved. The fix isn’t eating more on race day. It’s training your gut to handle race-pace intake beforehand, the same way you’d train your legs to handle race-pace effort.

Same logic applies to grabbing something new off the aid station table because it’s what’s there. If you haven’t tested a product on a long ride first, race day isn’t the time to find out how your stomach handles it.

More saddle time means bike fit matters more

The Olympic bike leg usually takes 1:10 to 1:20. At 70.3 you’re looking at well over three hours. That’s not a small increase, and it exposes fit issues an hour-long ride never will. If your position has been fine for years at Olympic distance, don’t assume it stays fine once you triple the saddle time. That’s usually the point where whether a bike fit is worth it stops being a hypothetical and starts being cheap insurance. Worth sorting out before it sorts itself out for you, uncomfortably, at hour two.

Should You Skip Olympic and Go Straight to 70.3?

You’ve just read what actually changes: the intensity, the swim volume, the bricks, the fuelling, the saddle time. So here’s the question this whole post has really been circling. Do you actually need to race an Olympic distance first, or can you skip straight to 70.3? The honest answer isn’t really about your race history. It’s about whether you already have the aerobic base to hold three hours of continuous work in one discipline before you start stacking three of them back to back. Triathlon-specific race experience helps, but it’s not the actual gate.

• Can swim close to 1,900 metres without stopping. Pace doesn’t matter yet, just continuous.
• Have ridden 2.5 to 3 hours in a single session and felt okay after, not wrecked.
• Can run 90 minutes without needing to walk.
• Have trained consistently, roughly 5 to 6 days a week, for at least 3 to 4 months.
• Have practiced eating and drinking during a session longer than 90 minutes.

You already know from the sections above that the bike leg alone runs well over three hours, and the run, off tired legs, often creeps toward two. Those numbers above are the floor for starting the block, not a preview of race day. Closing that gap is what the training block is for. If the size of it still surprises you, that’s useful information too, not a reason to panic.

If most of that’s a yes, especially if you’re coming from a running, cycling, or swimming background, skipping straight to 70.3 is a reasonable call. The distance rewards aerobic durability more than triathlon-specific race craft, and that kind of durability can be built in any single sport before you ever combine three.

If several of those are still a no, Olympic first isn’t just a box to check. It’s the cheaper place to find out what going wrong feels like. A bad pacing call there costs you an hour. At 70.3, the same mistake can cost you the back half of your run, and you won’t find out until you’re two hours deep with no easy way to bail.

Related Posts

If you’re still weighing up distances before you commit to the jump, Sprint vs Olympic vs Half vs Full: Triathlon Distances Explained lays out how the demands change across the board.

And if T100 is also on your radar, T100 vs 70.3 breaks down how that format compares for training and racing.

Sources & References

– Triathlete: How To Move Up in Distance From Olympic to 70.3

– NCBI/PMC: Exercise Intensity during Olympic-Distance Triathlon in Well-Trained Age-Group Athletes